bluuebunny/crossref_metadata_2025 huggingface dataset:
Spectrometric pK Determination of Daphnetin, Chlorogenic Acid and Quercetin
Authors: Sauerwald N. , Schwenk M. , Polster J. , Bengsch E.
Published: February 2015

Daphnetin, Chlorogenic Acid, Quercetin Polyphenols play an important role in the ‘immune system’ of plants. Since their charge is important for their physiological effect it is important to know their pKj values. Therefore, the pKj values of some plant contents such as daphnetin (pK = 7.36), chlorogenic acid (pK ≈ 8.5), and quercetin (pK1 = 7.03, pfro = 9.15) were determined in the pH range 7 -10 using UV/VIS spectroscopy. The decomposition kinetics of quercetin in alkaline solutions was taken into consideration by extrapolating the absorbance time curves to time zero (t = 0). The graphic method of absorbance (A) diagrams was used to determine the pKi values. In the case of quercetin the method of linear regression was also used for the determination.
Dimere und polymere Pnictidostannat(IV)-Anionen -Darstellung und Kristallstrukturen von Na2K3[SnP3], Na2Cs3[SnP3] und Na2K3[SnBi3] / Dimeric and Polymeric Pnictidostannate(IV) Anions -Preparation and Crystal Structures of Na2K3[SnP3], Na2Cs3[SnP3] and Na2K3[SnBi3]
Authors: Asbrand Matthias , Eisenmann Brigitte , Engelhardt Holger , Rößler Ute
Published: February 2015

The metallic lustrous compounds Na2K3[SnP3], Na2Cs3[SnP3], and Na2K3[SnBi3] were prepared from melts of mixtures of the elements. The isotypic compounds Na2K3[SnP3] and Na2Cs3[SnP3] crystallize in the orthorhombic system, space group Cmca (No 64), Z = 8, with lattice constants a = 1996.1 (4)/2047.9(4) pm, b = 669.5(1)/686.5(2) pm, c = 1494.5(2)/1617.8(3) pm. The structure is characterized by dimeric units [Sn2P6] 10- of edge-sharing [SnP4] tetrahe­dra, which are coordinated by the alkali cations. Na2K3[SnBi3] crystallizes in the orthorhombic system, space group Ibca (No 73), Z = 8, with lattice constants a = 718.2(1) pm , b -1692.6(2) pm, c = 2159.5(2) pm. In the anionic partial structure [SnBi4] tetrahedra are connected via common corners to infinite 1
∞[SnBi3]5- Zweier single chains. The sodium and potassium cat­ ions separate the chains from each other. Neglecting the distortions caused by covalent bonding and different radii both structure types can be classified as superstructure defect variants of the Li3Bi structure. Different orderings in the occupation of the tetrahedral voids lead to the variants in the anionic assemblies.
Some Applications of Ultrahigh Resolution 15N NMR Spectroscopy
Authors: Wrackmeyer Bernd , Kupče Ēriks
Published: February 2015

Ultrahigh resolution 15N NMR spectra were measured for two nitroalkanes (MeNO2 la, tBuNO2 1c), two isocyanates (tBuNCO 2c, Me3SiNCO 2d), four isothiocyanates (MeNCS 3a, EtNCS 3b, tBuNCS 3c, Me3SiNCS 3d), one carbodiimide (Me3SiNCNSiMe3 4d), one keteneimine [Me3SiNCC(SiMe3)2 5d], two sulphinyl imides (tBuNSO 6c, Me3SiNSO 6d), and N-tert-butyl-pyrrole 7c, in order to determine coupling constants J(15N ,I3C) and isotope induced chemical shifts 1∆12/13C (15N) at the natural abundance of the isotopes. The values 1∆12/13C (15N) can be separated into two groups, one dealing with NC single and another one with NC double bonds. In each group (with few exceptions), the values 1∆12/13C (15N) become more negative with a decrease in the absolute magnitude of l1J(l5N ,13C)l. The corresponding values 1∆14/15N (13C) show a sim ilar behaviour. However, N-substituted pyrroles appear to be exceptional in this respect.
Metallkomplexe mit biologisch wichtigen Liganden, CIV [1]. ortho-Palladierte Komplexe von N,N-Dimethyl-C-phenyl-glycinmethylester. Synthese von α-Aminosäure-Derivaten durch Insertion von Isocyaniden, CO, Alkenen und Alkinen in die Pd-C-Bindung / Metal Complexes of Biologically Important Ligands, CIV [ 1]. ortho-Palladated Complexes of N,N-Dimethyl-C-phenylglycine-methylester. Synthesis of α-Amino Acid Derivatives by Insertion of Isocyanides, CO, Alkenes, and Alkynes into the Pd-C Bond
Authors: Böhm Andreas , Polborn Kurt , Sünkel Karlheinz , Beck Wolfgang
Published: February 2015

N,N-Dimethyl-C-phenylglycinemethylester reacts with Pd(OAc)2 in acetic acid to give the orthopalladated, acetato bridged complex 1. Treatment of 1 with sodium halide affords the chloro, bromo, and iodo bridged compounds [Me2NC(H)(CO2Me)C6H4PdX]2 (2a -c) (X = halide). From 2a and 1,1′-bis(diphenylphosphino)ferrocene the phosphine bridged trinuclear complex 3 is obtained. Substitution of the amine ligand of 2a by the phosphino group is observed for the reaction of 2a with Ph2PC(Me)C(Me)PPh2. Insertion of 2,6-dimethyl-phenylisocyanide, CO, alkyl-vinyl-ketones, and diphenylacetylene into the Pd-C bond o f 2a -c provides the orthosubstituted organic and organometallic derivatives of phenylglycine 6a -c, 7, 8a -b and 9a -c. The crystal structures of 1, 4a, 6a, 7 and 9a were determined by X-ray diffraction.
Enantioselective Catalysis, 120 [1] New Optically Active Pyrrole-oxazolines
Authors: Brunner Henri , Haßler Bernd
Published: February 2015

14 new optically active pyrrole-oxazolines were synthesised from 2-pyrrole-carbonitrile or methyl 2-pyrrole-carboximidate and chiral amino alcohols. Their use in copper-catalysed enantioselective cyclopropanation reactions gave only low optical yields (3-14%ee).
Untersuchungen an Polyhalogeniden, XXXVI. Zur Kenntnis des Oktaiodid-Ions I8
2-: Darstellung und Kristallstruktur des [(Crypt-2.2.2)H2]l8, des [Ni(phen)3]I8 · 2CHCl3 und der Bis(N-alkylurotropinium) oktaiodide (UrR)2I8 mit R = Methyl und Ethyl / Studies on Polyhalides, XXXVI. On the Octaiodide Ion I8
2-: Preparation and Crystal Structure of [(Crypt-2.2.2)H2]I8, of [Ni(phen)3]I8-2CHCl3 and of the Bis(N-alkylurotropinium)octaiodides (UrR)2I8 with R = methyl and ethyl
Authors: Gräfe-Kavoosian Arista , Nafepour Shida , Nagel Klaus , Tebbe Karl-Friedrich
Published: February 2015

The new compound [(Crypt-2.2.2)H2]I8 has been prepared by the reaction of [(Crypt-2.2.2)H2](I3)2 with iodine in methanol. It crystallizes in the orthorhombic space group Pbcn with a = 11.476 (2), b = 13.589 (2), c = 22.888 (2) Å and Z = 4. The crystal structure has been refined to RF = 0.031 for 1618 reflections. It may be described as a layerlike packing of octaiodide anions I8
2-and diprotonated 2.2.2-Crypt as cations. The non planar octaiodide anion is built up from two triiodide groups and a bridging iodine molecule.

Tris(1, 10-phenanthroline)nickel(II) octaiodide bis(chloroform) crystallizes in the monoclinic space group P21/n with a = 11.683 (8), b = 21.717 (8), c = 20.752 (5) Å, β = 95.03 (5)° and Z = 4 formula units. The crystal structure has been refined to RF = 0.058 for 3894 reflections. The structure consists of two chloroform molecules, octahedrally coordinated complex cations [Ni(phen)3]2+ and nonplanar octaiodide anions I8
2- each composed of two asymmetric triiodide units I3
- weakly associated with an elongated bridging iodine molecule I2.

The already known structure of bis(N-methylurotropinium) octaiodide, (UrMe)2I8, has been verified and more accurate crystal data have been collected. The crystal structure has been refined to RF = 0.045 for 1908 reflections. The compound crystallizes in the monoclinic space group P21/c with a = 11.302 (2), b = 9.850 (2), c = 14.188 (2) Å , β = 92.59 (1)° and Z = 2. The anion has the shape of a stretched Z.

The structure of bis(N-ethylurotropinium) octaiodide (UrEt)2I8 has been determined and a new configuration (I3
-, I5
-) for octaiodide ions between Z (I3
- · I2 ·I3
-) and a “broken” configuration (I3
-, I5
-) has been observed. The compound crystallizes in the triclinic space group P1̄ with a = 9.741 (3), b = 11.815 (3), c = 15.426 (3) Å, α = 91.80 (2), β = 107.14 (2), γ = 90.04 (2)° and Z = 2. The crystal structure has been refined to RF = 0.037 for 3657 reflections.
Francoanellit K3Al5HPO4)6(PO4)2 · 12H2O: Struktur und Synthese durch topochemische Entwässerung von Taranakit / Francoanellite K3Al5HPO4)6(PO4)2 · 12H2O: Structure and Synthesis by Topochemical Dehydration of Taranakite
Authors: Dick Stefan , Zeiske Thomas
Published: February 2015

Single crystals of synthetic francoanellite K3Al5(HPO4)6(PO4)2-12H2O could be obtained for the first time by topochemical dehydration of taranakite crystals. An X-ray structure determination showed francoanellite to be the mineral with the second longest crystallographic axis described hitherto. Crystal data: space group R3c, a = 869.0(2), c = 8227(1)pm, Z = 6 , Rg = 0.042. Francoanellite is a layer structure mineral having six layers of composition [K3Al5(HPO4)6(PO4)2(H2O)12], connected by hydrogen bonds. The rigid layer is formed by columns of corner sharing hydrogen phosphate tetrahedra and AIO6-octahedra which are inter­ connected by additional six-coordinated Al ions. In trigonal holes of the layer orthophosphate ions are situated. The structure of francoanellite is very similar to the structure of taranakite K3H6Al5(PO4) 8 · 18H2O which has planar water interlayers between the Al-phosphate layers. A neutron scattering experiment with subsequent Rietveld refinement of the powder pattern gave the H-atom positions. Hydrogen bonds in francoanellite are formed within the rigid layers and between them.

During the reaction taranakite → francoanellite crystals in an intermediate stage of dehydration could be obtained. From the c-axis of 8858 pm and one-dimensional electron density projections it can be proposed that in these crystals every second water interlayer was lost and a first order staging product of the deintercalation of water from taranakite was formed.
Oxidation-Induced Acyl Group Transfer from Hydroquinone Esters to Nucleophiles
Authors: Reischl Gerald , El-Mobayed Medhat , Beißwenger Rudolf , Regier Klaus , Maichle-Mössmer Cäcilia , Rieker Anton
Published: February 2015

Bivalent oxidation of 3,5-di-tert-butyl-hydroquinone monoesters leads to phenoxenium ions, which can transfer an acyl group to nucleophiles. Based on this principle, dipeptides, glyco-amino acids and N-sulfonyl-amino acids were synthesized from hydroquinone esters of amino acids and p-toluenesulfonic acid. For this reaction, direct anodic and indirect mediated oxidation, as well as chemical oxidation with NBS or trisarylammoniumyl salts, was used. The mechanism of the acyl transfer is discussed in terms of a direct and/or a mediated process. A spirocyclic key intermediate was isolated and its molecular structure determined by X-ray crystallography.
Synthesis and Crystal Structure of [Cu2(OAc)4(NCMe)2] · 2MeCN
Authors: Ghassemzadeh Mitra , Aghapoor Kioumars , Neumiiller Bernhard
Published: February 2015

T etrakis-μ-acetato-bis(acetonitrile-N )-dicopper( II) bisacetonitrile (1) was syn thesized and characterized by IR spectroscopy and by an X-ray structure determination [Space group P21/n, Z = 2, lattice dimensions at - 70 °C: a = 1064.2(1), b = 1018.4(1), c = 1088.3(1) pm, β = 101.59(1)°, R1 = 0.048]. A ccording to the structural data the blue compound consists of centrosymmetric dimers [Cu2(OAc)4(NCMe)2] and noncoordinated acetonitrile molecules.
The Solution and Solid State Structure of L-Carnitine L-Tartrate
Authors: Schmidbaur Hubert , Schier Annette , Bayler Angela
Published: February 2015

L-Carnitine forms a salt-like 2:1 adduct with L-tartaric acid which crystallizes in the or-thorhombic space group P212121 with Z = 4 formula units in the unit cell. The lattice is composed of an L-tartrate dianion and two crystallographically independent L-carnitinium cations. The two cations show only very minor differences in their conformation. Anions and cations are arranged in separate stacks which are linked via hydrogen bonds. The tartrate anion and the carnitinium cations show standard geometries known from the structures of other salts of these ions, like the L-carnitine component of the R,L-carnitinium chloride or the dianion in alkali tartrates. The title compound has galenic advantages as an L-carnitine drug because of its non-hygroscopic properties. Aqueous solutions have been shown to contain solvated ionic components, i.e. L-tartrate and L-hydrogentartrate anions, L-tartaric acid (15:70:15) and carnitinium cations. The title compound can therefore be classified as a genuine L-carnitinium salt of L-tartaric acid.
Kristallstruktur von Cs2[B6H5(SCN)]/ Crystal Structure of Cs2[B6H5(SCN)]
Authors: Preetz W. , Zander S. , Bruhn C.
Published: February 2015

By reaction of [B6H6]2-with (SCN)2 in dichloromethane at -80 C° the thiocyanatohexaborate anion is formed and can be isolated by ion exchange chromatography on diethylaminoethyl (DEAE) cellulose. The X-ray structure determination of Cs2[B6H5(SCN)] (orthorhombic, space group Pbca with a = 9.506(5), b = 10.644(5), c = 21.857(5) Å, Z = 8) reveals that the SCN substituent is bonded via the S atom with the B-S distance of 1.885(9) Å and the B-S-C angle of 99.8(5)°. The SCN group is nearly linear (179.9(9)°).
Synthesis and X-Ray Structure of 1,3,5-Tri(phenylethynyl)benzene
Authors: Bochkarev Mikhail N. , Katkova Marina A. , Fedorova Elena A. , Makarenko Natalya P. , Schumann Herbert , Girgsdies Frank
Published: February 2015

1,3,5-Tri(phenylethynyl)benzene 1 obtained by coupling triiodobenzene with phenylacetylene shows an unusual non planar molecular structure.
Synthesis, IR and X-Ray Studies of Tetra(N,N′-tetraethyl-N″-benzoyl- phosphorictriamide)-tetra(μ-3-methoxo)-tetra(methanol)tetra-NickeI(II)
Authors: Ovchynnikov Vladimir A. , Amirkhanov Vladimir M. , Kapshuk Anatoliy A. , Sliva Tatyana Yu. , Glowiak Tadeusz , Kozlowski Henryk
Published: February 2015

A new nickel(II) complex with N,N′-tetraethyl-N″-benzoylphosphortriamide (HL = C6H5C(O)N(H)P(O)(NEt2)2) of composition Ni4L4(OCH3)4·(HOCH3)4 (1) has been synthe­ sized. The crystal and molecular structure of 1 has been determined from the X-Ray diffraction data (tetragonal, space group P4̄21c with a = 17.000(2) Å, c = 15.338(3) Å, Z = 2; R = 0.0399 for 1412 unique reflections). The structure is made up of cubane-like tetramers. In the corners of a cube there are 4 atoms of nickel and 4 atoms of oxygen of methoxy groups. The nickel atoms are characterized by a slightly distorted octahedral environment, which consists of three oxygen atoms of methoxy groups, carbonylic and phosphorylic oxygen atoms of the ligand L-, and an oxygen atom of a methanol molecule. The ligands L- coordinate to the metal ion forming a chelate via the oxygen atoms of carbonylic and phosphorylic groups.
Reaktion von [Co(But
2PH)2I2] mit [Ru3(CO)12]: Synthese und Röntgenkristallstrukturanalyse von [Ru3(CO)6(μ-H)(μ-I)2(μ-PBut
2)(But
2PH)]/ Reaction of [Co(But
2PH)2I2] with [Ru3(CO)12]: Synthesis and X-Ray Crystal Structure of [Ru3(CO)6(μ-H)(μ-I)2(μ-PBut
2)(But
2PH)]
Authors: Graf Marion , Merzweiler Kurt , Bruhn Clemens , Böttcher Hans-Christian
Published: February 2015

[Co(But
2PH)2I2] (1) reacts with [Ru3(CO)12] in refluxing toluene to give a mixture of products including the novel metal clusters [Ru3(CO)6(μ-H)(μ-I)2(μ-PBut
2)(But
2PH)] (2) and [Ru3(CO)7(μ-H)(μ-I)(μ-PBut
2)2] (3) besides the known complex [Ru3(CO)8(μ-H)2(μ3- PBut)(But
2PH)] (4). No cluster expansion products could be observed. Thus the cobalt compound acts merely as a phosphine and iodine transfer reagent. The molecular structures of the metal complexes 1 and 2 were determined by single-crystal X-ray structure analyses. 1 crystallizes in the tetragonal space group P4̄21c with a = 13.230(3), b = 13.230(3), c = 14.788(3)Å, V = 2588.4(9)A . 2 crystallizes in the monoclinic space group P21/c with a = 18.161(2), b = 10.292(2), c = 18.381(2)Å, β = 108.73(10)°, V= 3253.7(8)Å3.
Zur Kristallstruktur von Ho2Se3/ On the Crystal Structure of Ho2Se3
Authors: Urland Werner , Person Helmut
Published: February 2015

Starting from HoSe2-x powder and holmium metal bright brownish-yellow, plate-like single crystals of Ho2Se3 could be prepared by chemical transport with AlCl3. Holmium sesquiselenide crystallizes in the Sc2S3-type structure, space group Fddd, with lattice constants a = 1140,7(2), b -812,6(1) and c = 2423,9(3) pm.
Theoretische und experimentelle Untersuchungen zur Protonierung substituierter closo-Hexaborate -[B6H5HfacF]- und [B6H5HfacCH3]- / Theoretical and Experimental Investigations on the Protonation of Substituted closo-Hexaborates -[B6H5HfacF]- and [B6H5HfacCH3]-
Authors: Steuer B. , Peters G. , Preetz W.
Published: February 2015

The structural parameters and energies of the protonated compounds closo-[B6H5HfacF]- and closo-[B-H5HfacCH3]- are calculated by MP2/6-31G* optimization, as have the 1H, 11B , 13C and 19F NMR shifts using a tzp basis set and the RHF/GIAO method. The results for the octahedral molecule anions confirm the preferred localization of the additional proton in [B6H5HfacX]- in case of X = CH3 at the upper square pyramide topped by the ipso-boron atom, and in case of X = F at the lower one topped by the antipodal boron atom. The calculated NMR shifts are in good agreement with experimental data (this work). The higher BH frequencies observed for the protonated compounds as compared to the deprotonated parent clusters could be verified by ab initio frequency analyses.
Photoleitende Flüssigkristalle aus der Reihe der 2,3,6,7-Tetrakis(alkoxy)triphenylene / Liquid Crystals in the Series of 2,3,6,7-Tetraalkoxytriphenylenes
Authors: Rose Bernd , Meier Herbert
Published: February 2015

Stepwise bromination of the triphenylene 1 leads regioselectively to the monobromo and the dibromo compound 2 and 3, respectively (Scheme 1). In contrast to 1 and 2, the dibromo derivative 3 as well as the nitrile 4. obtained from 3 and CuCN, form thermotropic mesophases Dh. On irradiation of 3 and 4 a photocurrent can be measured in the crystalline state and an enhanced photocurrent in the LC phase.
Cobalt(II) Derivatives of Cyclic Phosphazenes: Synthesis, Characterization and Fungicidal Behaviour
Authors: Baranwal B. P. , Das S. S. , Singh Poonam
Published: February 2015

Chlorine atoms of hexachlorocyclotriphosphazene were substituted with -NH.C2H5, -NH.CH2C6H5 and -OC2H5 to yield organotriphosphazene ligands. Anhydrous cobalt(II) chloride formed a number of addition complexes with these ligands in different stoichiometric ratios. On the basis of electronic and IR spectra, magnetic moment, conductivity meas­urements and molecular weight determination, structures of these complexes have been sug­gested. The complexes were screened for their antifungal activities against Aspergillus flavus and Aspergillus niger.
Functionalized 1,1-Ethene Dithiolates as Ligands, V [1]. Synthesis and Crystal Structure of Palladium(II) and Platinum(II) Complexes with Dithioylidene Barbituric Acid Ligands. Molecular Structure of a 2,6-Diaminopyridine-Platinum(II) Barbiturate Complex
Authors: Weigand Wolfgang , Plener Veronika , Nöth Heinrich , Krossing Ingo , Knizek Jörg , Schmidt Martin
Published: February 2015

The 1,1-ethene dithiolato ligands (dithioylidene barbituric acids) 2a-f react with palladium(II) and platinum(II) compounds L2MCI2 [M = Pd, Pt; L = PEt3, PBu3, PPh3, 1/2 dppe, 1/2 (-)-DIOP, 1/2 2,9-dimethyl phenanthroline] to give the 1,1-ethene dithiolato metal complexes

. Compound 4a forms a 1:1 adduct (8) with 2,6-diaminopyridine. The compounds were characterised on the basis of their IR and NMR (1H, 13C, 31P) spectra. Complexes 4a, 4c, and 5a were further studied by X-ray structural analysis. The barbituric unit in 4a undergoes self-assembly through multiple hydrogen-bonding with complementary 2 ,6-diaminopyridine yielding the supramolecular complex 8
Synthesis and Conformation of Nucleoside 5'-S-Thiosulfates
Authors: Orzeszko Andrzej , Niedźwiecka-Komaś Anna , Stolarskic Ryszard , Kazimierczuk Zygmunt
Published: February 2015

Reaction between 5′-bromo-5′-deoxy- (or 5′-tosyl-) nucleosides and sodium thiosulfate gives the respective 5′-S-thiosulfates (nucleoside Bunte salts). Conformation and some physicochemical properties of the new nucleotide analogs are described
Synthesis and Dimroth Rearrangement of 6-Cyano-l,2,4-triazolo- [4,3-a]pyrimidin-5- and 7-ones. A Novel Alkylation with Orthoesters and a New Participation of the Cyano Group in the Rearrangement
Authors: El Ashry E. S. H. , El Kilany Y. , Rashed N. , Mousaad A. , Assafir H.
Published: February 2015

The cyclization products of 5-cyano-2-hydrazino-6-phenyl-3,4-dihydropyrimidin-4-one (6) with one carbon inserting agents have been confirmed to be of the 1,2,4-triazolo[4,3-a]pyrimidin- 5(8H)-ones type and not the respective 7-ones, by comparing their alkylated derivatives 10a, 11a, 27 and 28 with the product from the cyclization of the 3-methyl and 3-benzyl derivatives of 6. A novel alkylation process was found when triethyl orthoformate was used as a cyclizing agent. Dimroth rearrangement of 8, 14, 15, 24, 34 and 36 with 2% ethanolic KOH gave the respective triazolo[1,5-a]pyrimidinone 13, 18, 19, 25, 38 and 40, respectively. Using 10% ethanolic KOH led to a novel participation of the cyano group in the rearrangement whereby 8a gave 7-imino-5-phenyl-l,2,4-triazolo[1,5-a]pyrimidine 22
Penol Catalyzed Claisen ortho Ester Rearrangment of Allylic Alcohols with Trimethyl-β-hoxy) ortho Propionate
Authors: Iqbal Fazila , Ateeq Humayun. S. , Malik Abdul , Zeeshan  , Ali Zulfiqar
Published: February 2015

Phenol catalyzed Claisen ortho ester rearrangment of allylic alcohols with trimethyl-β-(methoxy) ortho propionate can be affected in relatively quick time and lower temperature with only 1.5 equivalents of ortho ester. The rearrrangement does not experience undesirable side reactions reported earlier in literature [3]
9-Silyl(-Germyl,-Stannyl) Substituted Derivatives of 1-(9-Fluorenyl)- germatranes. Synthesis, Characterisation, and Crystal Structures
Authors: Zaitseva Galina S. , Karlov Sergey S. , Siggelkow Bettina A. , Avtomonov Evgeni V. , Churakov Andrei V. , Howard Judith A. K. , Lorberth Jörg
Published: February 2015

9-Trimethylsilyl- and 9-trimethylgermyl substituted derivatives of 1-(9-fluorenyl)germatranes C13H8(R)Ge(OCH2CH2)3N (1 - 3) (1: R = H; 2: R = Me3Si; 3: R = Me3Ge) were prepared by the reaction of 9-tribromogermyl derivatives of fluorene C13H8(R)GeBr3 (4 - 6) with N(CH2CH2OSnAlk3)3 (7: Alk = Et; 8: Alk = Bu). 1-(9-Trimethylstannyl- 9-fluorenyl)germatrane (14) was synthesised by the reaction o f the germatrane (1) with Me3SnNMe2 . Formulas and structures were established by elemental analyses, (1H, 13C) NMR spectroscopy and mass spectrometry; crystal structures of 2 and 14 are reported.
Cleavage and Formation of P-C Bonds During an Unusual Kinnear-Perren Reaction
Authors: Plack Volker , Goerlich Jens R. , Schmutzler Reinhard
Published: February 2015

Treatment of triphenylmethyldichlorophosphine 1 with aluminium trichloride in the presence of tert-buty1 chloride leads, after hydrolysis, with high selectivity to di-tert-butylphosphinic chloride 5. The reaction is suggested to proceed via a chlorophosphinidene intermediate which is trapped by the alkyl chloride.
Ligand Redistribution Equilibria in Aqueous Fluoroberyllate Solutions
Authors: Schmidt Michael , Schmidbaur Hubert
Published: February 2015

The composition of aqueous fluoroberyllate solutions has been studied by 9Be and 19F NMR spectroscopy for various ratios of the beryllium and fluorine concentrations, and at different pH values. The equilibrium constants have been determined for the ligand exchange processes, which involve the species [Be(OH2)4]2+, [BeF(OH2)3]+, [BeF2(OH2)2], [BeF3(OH2)]- , and [BeF4]2-. These equilibria are shifted towards [BeF4]2- at high pH. No polynuclear fluoroberyllates have been detected. The fluoride exchange between the individual species is slow on the NMR time scale at room temperature, and separate sharp signals with the expected multiplicity are therefore recorded. Calculated 9Be chemical shifts are in good agreement with experimental data.
Elementorganische Verbindungen mit o-Phenylenresten, XXXI [1]. Charge-transfer-Komplexe von 2,3,7,8-Tetrakis(methylthio)chalkogenanthrenen mit 7,7,8,8-Tetracyanchinodimethan und Tetracyanethen / Organometalloidal Compounds with o-Phenylene Substituents, Part XXXI [1]. Charge-transfer Complexes of 2,3,7,8-Tetrakis(methylthio)chalkogenanthrenes with 7,7,8,8-Tetracyanoquinodimethane and Tetracyanoethene
Authors: Dötze Marc , Czepat Hendrik , Kudnig Jens , Klar Günter
Published: February 2015

The title compounds are prepared by slow evaporation of dilute solutions of the components. 2,3,7,8-Tetrakis(methylthio)thianthrene and -selenanthrene give isostructural 2:1 complexes with 7,7,8,8-tetracyanoquinodimethane (TCNQ) built up by donor/acceptor/donor units in which the TCNQ molecule is inserted into the cavity formed by two of the folded, oppositely arranged chalcogenanthrene molecules. These units are connected to chains by S -S contacts via the methylthio groups. From 2,3,7,8-tetrakis(methylthio)thianthrene and tetracyanoethene again a 2:1 complex is obtained, however, with a columnar structure in which two donor stacks are slightly interlinked by an acceptor stack thus forming a structure with alternating donor and acceptor molecules. The molecules are arranged in such a way that an optimum overlap of the HOMOs of the donors and the LUMOs of the acceptors, all of which are of π-type character according to MNDO calculations, is secured.
Darstellung und Kristallstruktur von Bis(triphenylphosphin)-decahydro-hypho-hexaboran [(PPh3)2B6H10]·CH2Cl2 / Synthesis and Crystal Structure of Bis(triphenylphosphine)-decahydro-hypho-hexaborane[( PPh3)2B6H10]CH2Cl2
Authors: Schaper T. , Preetz W.
Published: February 2015

By reaction of [B6H6]2- with (PPh3)3AgCl in dichloromethane the belt-shaped hypho-hexaborane adduct [(PPh3)2B6H10] is formed. The crystal structure of [(PPh3)2B6H10]·CH2Cl2 has been determined by single crystal X-ray diffraction analysis: orthorhombic, space group Pbnb with a = 9.804(3), b = 17.864(4), c = 21.334(2) Å, Z = 4.
Nachbargruppenbeteiligung bei der Dehydrierung cyclischer Amine vom Typ o-substituierter Anilinderivate / Neighbourgroup Participation with the Dehydrogenation of Cyclic Amines of the o-Substituted Aniline Type
Authors: Möhrle H. , Mehrens J.
Published: February 2015

The 2-Aminobenzylalcohols la - c produced with mercury-edta dehydrogenation the lactams 6a - c; the pipecoline 2b yielded the benzoxazine 3b indicating the participation of the nucleophilic hydroxymethyl group. The 2-aminobenzaldehydes showed a different behaviour in dependence on the ring size of the amine part: 7a, b led - via intermediate reaction of the hemiaminal 9 with the electrophilic formyl function - to the lactams 11a, b, while 7c gave rise to the aminoaldehyde 12 as major product and similarly the pipecoline 15 to the aminoketone 16. From 2′-(4-morpholinyl)-acetophenone (22) were received the lactam 31 and the aminoethanol 32, both by a twofold dehydrogenation.
Arsenic(III), Antimony (III) and Bismuth(III) Thiobenzoates: Crystal and Molecular Structures of M(SOCR)3 and PhSb(SOCPh)2
Authors: Singh Prit , Singh Sudha , Gupta Vishnu D. , Nöth Heinrich
Published: February 2015

Tris-thiobenzoates, Arsenic, Antimony, Bismuth Tris-thiobenzoates of arsenic, antimony and bismuth, M(SOCR)3 have been obtained from their oxides and characterized. In the X-ray crystal structure determinations of these, the group 15 atom and the three covalently bonded sulfur atoms are found to constitute a trigonal pyramid, the central atoms lie at a C3 axis. In the bismuth complex the thiobenzoate ligand tends to chelate. However, three comparatively short intermolecular M···S interactions are significant features for these molecules resulting in stacking of trigonal prisms providing an essentially six coordinate environment around arsenic and antimony and a nine-coordinate one for bismuth. The structure of PhSb(SOCPh)2 can be considered
Tetrazinn(II)-und Bariumtrizinn(II)-tetrakis[μ3 -tri-ter/-butyIsilylphosphan- diid]-Verbindungen mit einem Tetrametallatetraphosphacuban-Gerüst / Tetratin(II) and Barium Tritin(II) Tetrakis[μ3-tri-rm-butylsilylphosphandiide] Compounds with a Tetrametallatetraphosphacubane Core
Authors: Westerhausen Matthias , Krofta Mathias , Wiberg Nils , Knizek Jörg , Nöth Heinrich , Pfitzner Arno
Published: February 2015

The metalation of tri-terr-butylsilylphosphane with bis[bis(trimethylsilyl)amino]stannylen yields nearly quantitatively the tetrameric tin(II) tri-terf-butylsilylphosphandiide with a central Sn4P4 cubane moiety. Barium bis[tri-tert-butylsilylphosphanide] is accessible via the reaction of tri-tert-butylsilylphosphane with barium bis[bis(trimethylsilyl)amide] in the molar ratio 2 : 1 . This phosphanide reacts with bis[bis(trimethylsilyl)amino]stannylen to give barium tritin(II) tetrakis[μ3-tri-tert-butylsilylphosphandiide]. Crystallographic data of 1: P 212121, T = 193 K, a = 1532.6(3), b = 2120.2(4), c = 2194.0(5) pm, V = 7.129(3) nm3, Z = 4, R, = 0.0360 (9132 observed data [I > 2a( f) ] ) , wR2 = 0.1064 (all data); crystallographic data of 3: P 21/c, T = 193 K, a = 1927.35(1), b = 1799.27(2), c = 2201.35(2) pm, β = 93.010(1)°, V = 7.6234(1) nm3, Z = 4, R1 = 0.0321 (11993 observed data [I > 2σ(/)]), wR2 = 0.0772 (all data).
The Structure of Lithiumiodide 3-Tetrahydrofuran
Authors: Nöth Heinrich , Waldhör Ralf
Published: February 2015

LiI-3THF was obtained from the reaction of tmp2AH (tmp = tetramethylpiperidino) with Li-AsHPh in toluene/THF. It is more, conveniently prepared from LiH and iodine in THF. It forms molecule in the lattice, the Li ion being tetracoor-dinated in a slightly distorted tetrahedral fashion.
Benzo-18-krone-6 -Acetonitril (1/2): Kristallisation und Tieftemperatur- Röntgenstrukturanalyse / Benzo-18 -crown-6 -Acetonitrile (1/2): Crystallization and Low-Temperature X-Ray Analysis
Authors: Wijaya Karna , Moers Oliver , Blaschette Armand , Jones Peter G.
Published: February 2015

Benzo-18 -crown-6 -Acetonitrile (1/2), Crystal Structure Single crystals of the title complex resulted fortuitously during an attempt to co-crystallise MeN(SO2Me)2 with benzo-18-crown-6 from an MeCN solution at -30 °C. The crystal structure has been determined via data collection at -100 °C (monoclinic, space group P21/n, Z = 4). The nitrile molecules are located with their me­ thyl groups above and below the plane of the 18-membered crown ring, the Me hydrogen atoms being rotationally disordered about the MeCN axes; C(methyl)···O(crown) distances range from 309.4(3) to 384.9(3) pm.
Mesitylene Osmium(II) Complexes Containing the Functional Phosphane tBuP(CH2CO2Me)2 and Anionic Species Derived Thereof as Bi- and Tridentate Ligands
Authors: Henig Gerhard , Werner Helmut
Published: February 2015

The dichloroosmium(II) compound [(mes)OsCl2(L)] (2) with L = tBuP(CH2CO2Me)2 reacts with one or two equivalents of AgPF6 to give the mono- or dicationic complexes 3 and 4 containing the phosphanediyldiester as a bi- or tridentate chelating ligand. Complex 4 undergoes, in the presence of water, partial hydrolysis to give the difluorophosphatoosmium(II) derivative 5 in quantitative yield. Treatment of 4 with two equivalents of KOtBu affords by deprotonation at both CH2 groups of L the neutral complex 6, in which one PCHCO2Me unit of the dianionic ligand |tBuP(CHCO2Me)2]2- forms a five-membered and the other PCHCO2Me unit a three-membered ring with the metal. The reaction of 6 with water leads selectively to the formation of the chelate complex 7 containing the phosphanediylbis(carboxylate) [tBuP(CH2CO2)2]2- as a tripodal ligand.
Kristallstruktur des Doppelkomplexsalzes trans-(py2CH2)[Pt(OH)2(ox)2]transs-(py2CH2)[Pt(OH)(ox)2(H2O)]2·4H2O / Crystal Structure of the Double Complex Salt trans-(py2CH2)[Pt(OH)2(ox)2](H2O)]2·4H2O
Authors: Uttecht J.-G. , Preetz W.
Published: February 2015

By treatment of [Pt(ox)2]2- with hydrogen peroxide the octahedral trans-[Pt(OH)2(ox)2]2- is formed. From the saturated aqueous solution in the presence of dipyridiniomethane dications single crystals of the double complex salt trans-(py2CH2)[Pt(OH)2(ox)2] trans-(py2CH2)[Pt(OH)(ox)2(H2O)]2 · 4H2O were grown and an X-ray structure determination (tricli­nic, space group P1̄, a = 8.649(1), b = 11.189(3), c = 12.731 (2) Å, α = 79.075(12), β = 80.725(8), γ= 73.932(13)°, Z = 1) has been performed. The centrosymmetric trans-[Pt(OH)2(ox)2]2- is connected via hydrogen bonds between its hydroxide groups and the aqua ligands of two protonated complex anions trans-[Pt(OH)(ox)2(H2O)]- .
Neuartige Synthese und Molekülstruktur von Benzylkalium (thf) [KCH2C6H5]2 / Novel Synthesis and Molecular Structure of Benzyl Potassium (thf)[KCH2C6H5]2
Authors: Westerhausen Matthias , Schwarz Wolfgang
Published: February 2015

The reaction of potassium with hexamethyldi-stannane in a refluxing solvent mixture of toluene and tetrahydrofuran (ratio 10:1) yields the red tetrahydrofuran adduct of benzyl potassium (thf)[KCH2C6H5]2 due to the metalation of toluene by the potassium trimethylstannanide intermediate. The solid state structure of (thf)[KCH2C6H5]2 contains dimers with only one potassium coordinated to a tetrahydrofuran molecule. These dimers form a polymer through benzyl bridging with shortest K-C distances at 292 pm.
3,10,17,24-Tetra(1-methylethyl)-[29H,31H-tetrapyrido[2,3-b:2′,3′-g:2″-3″-I:2‴,3‴ -q]porphyrazinato-(2-)N29,N30,N31,N32]-nickel- [Eu(fod)3]4- Ein lösliches Pyridoporphyrazin / 3,10,17,24-Tetra(1-methylethyl)- [29H,31H-tetrapyrido[2,3-b:2′,3′-g:2″-3″-I:2‴,3‴-q]porphyrazinato-(2-)N29,N30,N31,N32]-nickel-[Eu(fod)3]4 - A Soluble Pyridoporphyrazine
Authors: Eichinger Karl , Brunmair Christoph , Bucher Martin
Published: February 2015

Starting from diethyl 5-(methylethyl)pyridine- 2,3-dicarboxylate the crystalline and highly soluble complex 3,10,17,24-Tetra(1-methylethyl)- [29H,31H-tetrapyrido[2,3-b:2′, 3′, -g:2″-3″-I:2‴, 3‴-q]porphyrazinato(2-)N29,N30,N31 ,N32]- nickel-[Eu(fod)3]4 was prepared. In this compound each europium ligand is coordinated to a pyridine N-atom and neighboured N-atom of the porphyrazine ring.
Untersuchungen zum ternären System Bi/Te/O, III. Bestimmung thermodynamischer Daten der ternären Verbindungen/Investigations on the Ternary System Bi/Te/O,III. Determination of Thermodynamic Data of Ternary Compounds
Authors: Schmidt P. , Hennig C. , Oppermann H.
Published: February 2015

The phase relations in the ternary system Bi/Te/O have been determined in previous studies by solid state reactions. Thermodynamical data have now been obtained for the pertinent equilibria. The heats of solution of Bi2O3, Bi12TeO20, Bi10Te2O19, Bi16Te5O34, Bi2TeO5, Bi2Te2O7, Bi2Te4O11 and TeCl4 were determined in 4N HCl. From these the enthalpies of formation of bismuth tellurites at 298 K have been derived:

⊿H°b (Bi12TeO20, f, 298) = -901,6 ± 8 kcal/mol,

⊿H°b (Bi10Te2O19, f, 298) = -856,1 ± 9 kcal/mol,

⊿H°b (Bi16Te5O34, f, 298) = -1519,5 ± 17 kcal/mol,

⊿H°b (Bi2TeO5, f, 298)= -222,8 ± 3 kcal/mol,

⊿H°b (Bi2Te2O7, f, 298)= -299,4 ± 4 kcal/mol,

⊿H°b (Bi2Te4O11, f, 298)= -448,2 ± 7 kcal/mol.
Decomposition of Ethoxyethynyl(trimethyl)tin - Studied by 119Sn and 13C NMR Spectroscopy
Authors: Wrackmeyer Bemd , Ponomarev Sergei V.
Published: February 2015

The thermally induced decomposition of ethoxyethynyl(trimethyl)tin (1) was studied by 119Sn NMR which revealed the formation o f bis(trimethylstannyl) ketene (2) as the major product, bis(trimethylstannyl) acetic acid ethyl ester (3) as a minor product, and a small amount o f tetramethyltin (4). Full NMR data sets, including coupling constants and isotope induced chemical shifts 1Δ12/ 13C(119Sn) are provided for 1-3 . The first example o f ultra-high resolution 119Sn NMR is shown
Organoactinide Chemistry: Polysilylated Actinidocenes of Thorium, Uranium, and Neptunium
Authors: Apostolidis Christos , Edelmann Frank T. , Kanellakopulos Basil , Reißmann Ulrike
Published: February 2015

The preparation and characterization of three homologous actinidocenes of the composition An[η8-C8H5(SiMe3)3-1,3,5]2 (An = Th (1), U (2), Np (3)) is reported. Due to the presence of six trimethylsilyl groups these sandwich complexes are quite volatile and soluble in non-polar organic solvents.
Darstellung und Eigenschaften von Tetra(n-butyl)ammonium-cis-diacidooxophthalocyaninato( 2-)niobaten(V) und -tantalaten(V); Kristallstruktur von (nBu4N)CIS[Nb(F)2Opc2-]
Authors: Schweiger Karsten , Hückstädt Heiner , Homborg Heiner
Published: February 2015

Tetra(n-butyl)ammonium ds-diacidooxophthalocyaninato(2-)niobates(V) and -tantalates(V), (nBu4N)cis[M(X)2Opc2-] (M = Nb, Ta; X = F, Cl, NCS, N3), are obtained by the reaction of cis[M(Cl)3pc2-] or cis[M(Cl}Opc2-] (M = Nb, Ta) with the respective tetra(n-butyl)ammonium salt. (nBu4N)cis[Nb(F)2Opc2-] crystallizes in the monoclinic space group P21/n with cell parameters a = 13.460(5), b = 13.820(5), c = 23.360(5) Å, ß = 92.640(5)°, Z = 4. The heptacoordinated Nb(V) atom is surrounded by four isoindole nitrogen atoms (Niso) of the pc2- ligand, two fluorine atoms and one oxygen atom in a distorted square-base-trigonal-cap polyhedron. Nb(V) is displaced out of the centre of the (Niso)4 plane (Ct(Niso)) towards the acido ligands (d(Nb-Ct(Niso)) = 1.241 Å). The average (Nb-Niso), (Nb-F), and (Nb-O) distances are 2.300, 1.957, and 1.720(5) Å, the (F-Nb-F) and the average (O-Nb-F) angles are 79.8(2) and 91.8°, respectively. The pc2- ligand is concavely distorted. Typical π-π*-transitions of the pc2- ligand are observed in the UV/Vis spectra at ca. 14500 and 29300 cm-1 . Vibration frequencies υas,s(M-X), υ(M-O) and δ(X-M-0) have been assigned.
Kristallstruktur, Infrarot- und Ramanspektren sowie thermische Zersetzung von Magnesiumtetrahydrogendimesoperiodat, MgH4I2O10 · 6H2O
Authors: Nagel R. , Botova M. , Pracht G. , Suchanek E. , Maneva M. , Lutz H. D.
Published: February 2015

Crystal structure, DRIFT, infrared and Raman spectra, and the results of thermal analyses of the hitherto wrongly as Mg(H4IO6)2 · 4H20 and Mg(IO4) · 8H2O described dimesoperiodate MgH4I2O10 · 6H2O and of the isostructural zinc compound are presented. The compounds crystallize in the monoclinic space group P21 (Z = 2) with a = 1071.0(2), b = 547.0(1), c = 1194.9(2) pm, and β = 112.58(3)° and a = 1073.3(3), b = 545.3(2), c = 1188.3(5) pm, and β = 112.52(3)°, respectively. The structure, which was refined from X-ray single crystal data of the magnesium compound (R1 = 2.72%, 3824 independet reflections), is built up from isolated distorted M(H2O)6
2+ octahedra and dimesoperiodate ions H4I2O10
2- connected by a network of hydrogen bonds formed by the H4I2O10
2- ions and six crystallographically different hydrate H2O molecules. The strength of the hydrogen bonds ranges from unusually weak bonds corresponding to uncoupled (isotopically dilute samples) OD stretching modes of > 2600cm-1 and very strong ones (νOD: < 2200 cm-1). The IO stretching modes of the transconfigurated H4I2O10
2- ions are assigned to terminal I-O groups (816 cm-1), I-OH groups (746 and 762cm-1) and bridging I-O groups (618 and 647cm-1). On heating, MgH4I2O10 · 6H2O undergoes dehydration in the range of 373 - 485 K (Differential Scanning Calorimetry) to two different polymorphs of magnesium metaperiodate (H4I2O10
2-→2IO4
- + 2H2O). Anhydrous Mg(IO4)2 is instable. Above 423 K (high-temperature Raman data), it decomposes to magnesium iodates.
Die Kristallstrukturen von [(TMEDA)LiCl]2·Toluol und [(MeCN)2LiCl]n
Authors: Chitsaz Soheila , Pauls Jochen , Neumüller Bernhard
Published: February 2015

Single crystals of [(TMEDA)LiCl]2 · toluene (1) and [(MeCN)2LiCl]n (2) can be obtained by dissolving LiCl in TMEDA or acetonitrile and crystallization (after addition of toluene for 1) at -30 °C. 1 is a dimer in the solid state while 2 is polymeric. 1 crystallizes in the space group I 2/a, Z = 4, with lattice dimensions at -90 °C: a = 1475.3(1), b=1112.7(2), c = 1615.0(2) pm, β = 103.44(1)°; Rx = 0.0739 with a disorder of the TMEDA ligand in two twist-positions. Crystals of 2 possess the space group Pbcm, Z = 4, with lattice dimensions at -80 °C: a = 1256.8(2), b = 775.2(1), c = 758.6(1) pm;R1 = 0.0419.
Preparation and Structure of Cyclic Gallium(III) and Gallium(II) 2-Amino-ethyl-amides
Authors: Schmidt Eva S. , Schier Annette , Mitzel Norbert W. , Schmidbaur Hubert
Published: February 2015

The reaction of N,N′-di(tbutyl)-ethane- 1,2-diamine with NaH followed by anhydrous GaCl3 (molar ratios 1:2 :1) gives mainly an insoluble bis(diamido)gallium chloride together with a low yield (28%) of a soluble monocyclic dichlorogallium-[2-(tbutylamino)-ethyl-(tbutyl)amide], Cl2Ga(tBuNH-CH2CH2-NtBu) 1, the structure of which has been determined. Metallation of the same diamine with tbutyl-lithium and GaCl3 (1:2:1) gave small quantities of the corresponding dinuclear, bicyclic gallium(II) compound 2, [(tBuNH-CH2CH2-NtBu)GaCl]2 with a Ga-Ga single bond connecting the two units, as again shown by a single crystal X-ray diffraction analysis.
Reactions of Amino-imino-boranes with Transition Metal Halides and Substituted Transition Metal Halides
Authors: Böck Barbara , Nöth Heinrich , Wietelmann Ulrich
Published: February 2015

The aminoiminoborane tmp-B=NCMe3 (1) adds to TiBr4 or ZrCl4 in a 1:1 ratio while PdCl2 adds 1 in a 1:2 ratio. In these new compounds the NBN unit is almost linear and the configuration corresponds to an allene. On the other hand 1 and Ti(OR)4 compounds and Ti(NMe2)4 give N metallated diaminoboranes tmp-B(X)-NCMe3EX3 (X = OR, NMe2). Mixed compounds Ti(OR)3-nXn lead to diaminoboranes with BOR groups while the TiCl bond inserts into the B = N bond of 1 to produce tmp-BNMe2-NCMe3TiCl3. Hydrolysis of this compound leads to a spirocyclic dititanoxane with a short linear Ti-O-Ti bond and pentacoordinated Ti centers carrying two Cl atoms each. Spirocycles with a BN2E (E = Ti, Nb, Ta, Pd) unit are formed when 1 is allowed to react with TiCl4, NbCl5, TaCl5 and PdCl2. The palladium compound 16 is dimeric, and dimerization occurs via Pd-Cl bridges.

The aminoiminoborane tmp-B=NC6H3-2,6-iPr2 reacts with the titanium compounds in the same manner as 1, however without formation of spirocycles.
A Curious Case of Partial Spontaneous Resolution on Crystallization of a Racemate. The Crystal and Molecular Structures of N-Acetyl-DL-alanine Methylester and iV-Acetyl-L-alanine Methylester
Authors: Müller Gerhard , Lutz Martin
Published: February 2015

N-Acetyl-L-alanine methylester crystallizes in the orthorhombic space group P212121 with one molecule in the asymmetric unit (a = 7.768(1), b = 9.606(1), c = 10.215(2) Å, Z = 4). The individual molecules are linked into infinite strands by intermolecular hydrogen bonds between the amide hydrogen atom as donor and the acetyl oxygen atom as acceptor. The strands run parallel to the crystallographic b axis. The respective racemate, N-acetyl-DL-alanine methylester, crystallizes in the monoclinic space group P 21/n with three molecules in the asymmetric unit (a = 14.442(3), b = 8.467(2), c = 19.336(5) Å, β = 93.68(1)°, Z = 12). Again, the individual molecules are linked into infinite strands by N-H···O= Cacetyl hydrogen bonds which run along the crystallographic a axis. The individual strands are made up of molecules of opposite chirality in a 2:1 ratio. More specifically, one set of strands consists of molecules in the sequence [D, D, L,]∞ while a second set has the sequence [L, L, D]∞ as imposed by the centrosymmetry o f the space group. Thus, although crystals o f N-acetyl-DL-alanine methylester contain equal amounts of the molecules of opposite chirality, the strand formation through intermolecular hydrogen bonds leads to an incom plete resolution of the racemic mixture of molecules within one strand. The reason for the preference of the observed structure o f N-acetyl-DL-alanine methylester over spontaneous resolution is seen in the optimization of hydrogen bonding within one strand versus the overall crystal packing energy. Some principles of the crystallization of achiral molecules, chiral molecules, and racemates are briefly reviewed, as is the phenomenon of spontaneous resolution.
Preparation and Structure of Lithium Bis[cis-ethene-l,2-di(tbutylamido)]gallate(III) Tetrahydrofuran
Authors: Schmidt Eva S. , Mitzel Norbert W. , Schmidbaur Hubert
Published: February 2015

The dilithium diamide reagent obtained from N,N′-di(tbutyl)-1,4-diazabutadiene and two equivalents of lithium metal reacts with anhydrous gallium trichloride in tetrahydrofuran / hexane, followed by treatment with metallic potassium, to give the title compound in about 40% yield. Cyclic imides of gallium(III) and gallium(II) are by-products of this process. The structure of Li{[cis-C2H2(NtBu)2]2Ga} has been determined from single crystals containing one mole equivalent of tetrahydrofuran. The gallium atom is chelated by two diamide ligands. One of the five-membered chelate rings is planar while the second one is folded at its nitrogen atoms. The lithium atom is η4 -coordinated to the 1,4-diazabutene(2) unit of this ring and further to the oxygen atom of the solvent molecule.
The Chemical Evolution of a Nitrogenase Model, XXIY. Correlational Analysis of Effects of Organic Acids on in vitro MoFe-Protein Substrate Reduction Activities
Authors: Schrauzer Gerhard N. , Palmer John G.
Published: February 2015

Among 29 organic acids whose effects on the in vitro enzymatic substrate reducing activity on the MoFe-protein of nitrogenase have been investigated, 12 acids stimulate the in vitro C2H2-reducing activities in proportion to the H+-reducing activities. A second group com­ prised of eight acids significantly stimulates the H+-reducing activity but has only modest stimulatory effects on C2H2-and N2-reducing activities. A third group of nine acids causes only slight increases of MoFe-protein substrate reducing activities. The stimulatory effects of acids on MoFe-protein substrate reducing activity depend on their mode of interaction with molybdenum. Hydroxycarboxylic acids acting as bidentate ligands such as homocitric acid and its derivatives leave a sufficient number of molybdenum coordination sites available for interactions with the substrates, they have the highest stimulatory effects both on the C2H2-and N2-reducing activities, and their H+-reducing activities are not inhibited by CO. Acids acting as tridentate ligands, which include citric acid, have weaker stimulatory effects on the C2H2-and especially on the N2-reducing activities, and CO inhibits their H+-reducing activity. Whereas with the first group of acids the C2H2-reducing activities are linearly correlated with H+-reducing activities, the N2-reducing activities are directly correlated with H+-reducing activities in the presence of CO, and the association is exponential rather than linear. This exponential dependence is consistent with a stepwise mechanism of nitrogen reduction via diazene and hydrazine as the intermediates, the latter blocking one molybdenum coordina­tion site prior to its reduction to NH3. In the reduction of C2H2 to C2H4, no such blockage occurs as product C2H4 does not accumulate at the active site and is not reduced further.
Elektrostatische Aktivierung der SNAr-Reaktivität durch Sulfonyloniosubstituenten/Electrostatic Activation of SNAr-Reactivity by Sulfonylonio Substituents
Authors: Weiss Robert , Pühlhofer Frank
Published: February 2015

4-Fluorobenzenesulfonyl chloride (1) and pentafluorobenzenesulfonyl chloride (2) are transformed into the corresponding N-sulfonylpyridinium triflates 4a-d by treatment with one equivalent of the reagent pair L/TMSOTf (L = 4-dimethylaminopyridine (DMAP), 4-ferf-butylpyridine (TBUPY), 1-methylimidazole (NMI); TMSOTf = trimethylsilyl triflate). Due to the electrostatic effect of the sulfonylonio function, SNAr reactions on these systems can be performed under mild conditions. So the reaction of 2 with excess DMAP/TMSOTf leads by way of peronio substitution to hexakis[(4-dimethylamino)-l-pyridinio]benzene hexa-kis(trifluoromethansulfonate) (7) [22] at room temperature. Additionally, a new reaction path to 4-(1-pyridinio)-substituted benzenesulfonamides, a class of pharmaceutically interesting substances, is shown.
N-Ferrocenyl Amines Bearing Boryl and Silyl Substituents at the Nitrogen Atom, Studied by 57Fe NMR Spectroscopy
Authors: Wrackmeyer Bernd , Maisel Heidi E. , Herberhold Max
Published: February 2015

A series of ferrocene sandwich compounds such as N-ferrocenyl amine, Fc-NH2 (1), the Nsilylated derivatives Fc-NH -SiMe3 (2), Fc- NH -SiMe2H (3), (Fc-NH )2SiMe2 (4), the N-silyl- N-boryl derivatives Fc-N(SiMe3)(9-BBN) (5) (9-BBN = 9-borabicyclo[3.3.1]nonyl) and Fc- N(SiMe3)BEt2 (6), and the N-borylated derivatives Fc-NH -(9-BBN) (7) and Fc-NH -BEt2 (8) were studied by 57Fe NMR spectroscopy. The δ57Fe data reveal that CFcN(pp)π interactions lead to 57Fe nuclear magnetic deshielding (with respect to ferrocene) which is attenuated if competing BN(pp)π bonding becomes efficient (7, 8).