bluuebunny/crossref_metadata_2025 huggingface dataset:
Aktivierung von CO2 an Übergangsmetallzentren: Struktur und Reaktivität eines C-C-Kopplungsproduktes von CO2 und 2.3-Dimethylbutadien am elektronenreichen Nickel(O) / Activation of CO2 at Transition Metal Centers: Structure and Reactivity of a C-C-Coupling Product of CO2 and 2,3-Dimethylbutadiene at Electron-Rich Nickel(O)
Authors: Walther Dirk , Dinjus Eckhard , Sieler Joachim , Thanh Nguyen Ngoc , Schade Wolfgang , Leban Ivan
Published: February 2015

Carbon dioxide reacts with 2,3-dimethylbutadiene and bis-cyclooctadiene(1,5)-nickel(O) in the presence of N,N′-tetramethyl-ethylendiamine (tmeda) to form [(3,4,5-η3)-3,4-dimethyl-3-pentenylato](N,N′-tetramethyl-ethylendiamine)-nickel(II) as the product of the oxidative coupling of CO2 and the diene. The deep red complex crystallizes in the rhombic space group Pbca. The structure was determined by an X-ray analysis. The monodendate carboxylate group, the π-allyl system and a N-atom of tmeda form a planar coordination sphere around the central atom. The distance between Ni and the second N-atom of tmeda is very long (2.314 Å).

Reaction of the complex with R−X (R: H, CH3) yield 3-unsaturated carboxylic acids; tmeda can be substituted by 2,2′-bipyridine.
Photochemische Reaktionen von Übergangsmetall-Olefin-Komplexen, VII [1] Die Reaktion von Triearbonyl-η6-cyclooctatetraen-chrom(0) mit 6-mono-und 6.6-disubstituierten Fulvenen / Photochemical Reactions of Transition Metal Olefin Complexes, VII [1] The Reactions of Tricarbonyl-η6-cyclooctatetraene-chromium(0) with 6-Mono-and 6,6-Disubstituted Fulvenes
Authors: Kreiter Cornelius G. , Kurz Hans
Published: February 2015

Tricarbonyl-η6-cyclooctatetraene-chromium(0) (1) reacts photochemically with 6-mono- and 6,6-disubstituted fulvenes (2-7) in a substitution-oxidative rearrangement-reaction to dicarbonyl-η-1′-3':1″-5″-(cycloocta-2′,4′,6′-trien-1′,8′-ylene-cyclopentadienylidene-methane)chromium complexes (8−13). Tricarbonyl-η-6,6-dimethylfulvene-chromium(0) (16) reacts with cyclooctatetraene, bicyclo[6,1,0]nona-2,4,6-triene and anti-9-methoxybicyclo-[6,1,0]nona-2,4,6-triene in a similar manner and forms 8 and 2-bicyclo[6,1,0]nona-4′,6′-dien-2′,3′-ylene-2-cyclopentadienylidene-propane complexes (19, 20). In addition to 13 6-dimethylaminofulvene (7) yields with 1 dicarbonyl-η-1′,6′,7′: 1″-5″-(2-cyclohepta-2′,4′,6′-trien-7′-ylidene-1 -cyclopentadienylidene-1-dimethylamino-ethane)-chromium (14) which involves an unexpected contraction of the eight-membered ring. The constitutions of 8−15 and 19−20 were determined by IR and NMR spectroscopy.

In Cr(CO)2[C(C6H5)2(C5H4)(C8H8)] (9) one of the phenyl groups shows hindered rotation around its two fold axis.
Peroxofluorokomplexe der Übergangsmetalle, V [1-3] Kristallstruktur von K2Ti(O2)F4 · H2O (orange) mit einem Di(μ-fluoro)diperoxo-hexafluorodititanat(IV)-Anion / Transition Metal Peroxofluoro Complexes, V [1-3] Crystal Structure of K2Ti(O2)F4 · H2O (orange) with a Di(μ-fluoro)diperoxo-hexafluorodititanate(IV) Anion
Authors: Schmidt Roland , Hiller Wolfgang , Pausewang Gerhardt
Published: February 2015

Orange crystals of K2Ti(O2)F4 · H2O have been obtained from aqueous solution. The crystal structure (space group P21/n, a = 604.3(3), b = 1424.6(4), c = 761.0(2) pm, β = 103.98°, Z = 4, dc = 2.63 gcm-3, dm = 2.62 gcm-3, R = 0.051 for 2257 independent reflections) shows isolated di(μ-fluoro)-bridged [Ti2(O2)2F8]4- anions, which are inter­connected by hydrogen bonded H2O forming infinite chains.
Quantum Chemical Interpretation of the Photoinitiated Autoxidation of Sulphite Catalysed by Ferric Ions
Authors: El-Wakil A. M. , Soliman M. S. , Farag A. B.
Published: February 2015

Autoxidation of sulphite is the first well known chain reaction proceeding through free radicals in solutions. Dark and photochemical autoxidation of sulphite were stated to take place by the same mechanism except in the initial steps. It was found that the formation of sulphite radicals in photoinitiated autoxidation of sulphite which is a metal catalysed reaction as well as the classical thermal reaction is due to the absorption of photons by ferrisulphite complexes rather than sulphite itself. Confirmation of this finding was achieved spectrophotometrically as well as by the fact that such complexes are specified by very high stability constants. The present work is a further evidence for the presence of such complexes and to cover the gap present before in the literature data. Quantum mechanical calculations using the extended Hückel molecular orbital method has proved that the range of absorption by sulphite lies in a region at which sulphite alone does absorb at all, and the absorption process is thus due to the formation of ferrisulphite complexes.
Untersuchungen an quartären Pyridinium-Salzen, XV [1] Pseudobasen und Redoxprodukte bei der Umsetzung von Pyridinium-Salzen mit Alkoholat / Investigations of Quaternary Pyridinium Salts, XV [1] Pseudobases and Redox Products in the Reaction of Pyridinium Salts with Alcoxides
Authors: Gündel Wolf-H.
Published: February 2015

Mono-and diquaternary pyridinium salts substituted in 3-position with electron with-drawing groups, react with alcohols under basic conditions to give 6-alcoxy-1,6-dihydro-pyridines. Symmetric dipyridinium salts react in aqueous alkaline solution to products with 6-pyridone and dihydropyridine moiety. This redox reaction depends on the length of the bridge connecting the pyridinium rings. Pyridinium salts can be reduced by aluminiumtriisopropoxide to 1,4-dihydropyridines.
Notizen: Einkristall-Daten der Hochdruck- Hochtemperaturphase von SrSi2 / Single Crystal Data of the High Pressure-High Temperature Phase of SrSi2
Authors: Evers Jürgen , Oehlinger Gilbert , Weiss Armin
Published: February 2015

The high pressure-high temperature phase of SrSi2 is a stoichiometric representative of the a-ThSi2 type of structure. A single crystal investigation leads to interatomic distances Si-Si: 233.0(2) pm (1 x) and 248.9(2) pm (2 x), Sr-Si: 319.1(4) pm (4 x) and 334.7(4) pm (8 x), Sr-Sr: 410.8(3) pm (4 x) and 443.8(3) pm (4 x).
Darstellung und Kristallstruktur von monoklinem Arsen(III)antimon(III)oxid, AsSbO3 / Preparation and Crystal Structure of Monoclinic Arsenic(III) Antimony(III) Oxide, AsSbO3
Authors: Bodenstein Doris , Brehm Axel , Jones Peter G. , Schwarzmann Einhard , Sheldrick George M.
Published: February 2015

Monoclinic AsSbO3 was prepared by heating an equimolar mixture of AS2O3 and Sb2O3 to 670 K in an evacuated quartz tube. The crystal structure was determined [P21/n, a = 458(1), b = 1316(2), c = 544(1) pm, β = 95.0(1)°, Z = 4, R = 0.055 for 745 reflections] and found to be isostructural with the As2O3 modification claudetite I. Mean As-O and Sb-O bond lengths are 180 and 195 pm, respectively. There is no crystallographic evidence for any significant As/Sb disorder.
Über Hexaiodoplatinate(IV) M2PtI6 (M = K, Rb, Cs, NH4, Tl) Darstellungsverfahren, Eigenschaften und Kristallstrukturen / On Hexaiodoplatinates(IV) M2PtI6 (M = K, Rb, Cs, NH4, Tl) -Preparation, Properties and Structural Data
Authors: Thiele Gerhard , Mrozek Christian , Kämmerer Dieter , Wittmann Kurt
Published: February 2015

Crystals of hexaiodoplatinates(IV) M2PtIe (M = K, Rb, Cs, NH4, Tl) have been obtained by heating PtI4 or H2FtCl6 in highly concentrated aqueous solutions of MI in the presence of small amounts of HI and I2 in an ampoule for 24 h at 160 °C. The structural parameters were determined from single crystal data. In water less soluble compounds with M = Rb, Cs, NH4 show the cubic K2PtCl6 structure, whereas the easily water soluble salts with M = K, Tl both crystallize in a tetragonally distorted version of this structure type.
Ringförmige [(GeTe2)4Te2]8- -Anionen im Na8Ge4Te10(II) / Cyclic [(GeTe2)4Te2]8- -Anions in Na8Ge4Te10(II)
Authors: Eisenmann Brigitte , Schäfer Herbert , Schwerer Heike
Published: February 2015

Na8Ge4Te10 exists in two modifications I and II, of which structure I was determined previous by [3]. Modification II crystallizes in the triclinic system, space group P1̄ with the lattice constants:

a = 1070.1(5) pm, b = 963.9(5) pm, c = 792.3(4) pm

α = 67.9(1)°, β = 70.7(1)°, γ = 68.3(1)°.

In the structure there are [Ge4Te10]8- anions in the form of six-membered rings [(GeTe2)4Te2]8-.
Reaktionen von α-Ketoaziden mit N,N-Dimethylammo-nitrosobenzol Darstellung von α-Imino-β-ketonitrilen und deren Redoxeigenschaften / Reactions of α-Ketoazides with N,N-Dimethylamino-nitrosobenzol Synthesis of α-Imino-β-Ketonitriles and their Redox Properties
Authors: Knittel Dierk
Published: February 2015

A survey about the reaction between α-azidoacetophenones with aromatic nitroso compounds is given. The synthesis of α-imino-β-ketonitriles and some electrochemical properties of this class are described.
Strukturchemie von Verbindungen des penta-koordinierten Siliciums. Quadratisch-pyramidale Geometrie im Bis (tetramethylethylendioxy)fluorsilan -Anion / Structural Chemistry of Penta-coordinated Silicon. Square-Pyramidal Geometry in the Bis(tetramethylethylenedioxy)fluorosilane Anion
Authors: Schomburg Dietmar
Published: February 2015

The geometry around the penta-coordinated silicon atoms in the two crystallographically independent molecules in tetramethylammonium-bis(tetramethylethylenedioxy)fluorosilane dichloromethane solvate is distorted from the trigonal bipyramid towards the square pyramid by 69.1 % and 52.3%, resp. [N(CH3)4]+[FSi(OC(CH3)2C(CH3)2O)2]-. CH2Cl2 crystal­lizes in the monoclinic space group P21/n, Z = 8 with a= 20.926(6), 6= 15.117(1), c = 17.008(4) Å, β = 114.88(2)°. The structure was refined to R = 0.084 using 2203 independent reflections.
Gehinderte Ligandbewegungen in Übergangsmetallkomplexen, XIX [1]. Oktaedrische Wolfram-Olefin-Komplexe mit Bisphospbinoethan-Liganden / Hindered Ligand Motions in Transition Metal Complexes, XIX [I]. Octahedral Tungsten Olefin Complexes with Bisphosphinoethane Ligands
Authors: Kreiter Cornelius G. , Koemm Ulrich
Published: February 2015

(OC-6-32)-W(CO)3[(CH3)2PC2H4P(CH3)2] (olefin) complexes (9-14) were prepared photochemically from W(CO)4[(CH3)2PC2H4P(CH3)2](l) via W(CO)3[(CH3)2PC2H4P(CH3)2]- (THF) (2) and the electron poor olefins dimethyl inalonate(3), fumarate (4), inothylfumarate (5), fluorofumarato (6), chlorofumarato (7) and bromofumarate (8). The stereoche­mistry of 9-14 was elucidated by IR and NMR spectroscopy. The hindered rotations of the olefin ligands in 9-14 were studied by D-NMR spectroscopy. 11-14 form two diastereomeric isomers when the olefin rotation is freezed. The spectroscopic behaviour of the dimethyl fumarato complex 10 gives unambiguous proof for the rotation of the olefin ligand around the metal-olefin-bond. Alternative motions are ruled out.
Übergangsmetall-Komplexe mit Schwefelliganden, V. Synthese, Reaktivität und Struktur von Carbonyl-, Phosphin-und Hydrazin- Eisen(II)-Komplexen mit zwei- und vierzähnigen Schwefelliganden / Transition Metal Complexes with Sulfur Ligands, V. Synthesis, Reactivity and Structure of Carbonyl-, Phosphine-, and Hvdrazin-Iron(II). Complexes with Two-and Fourdentate Sulfur Ligands
Authors: Sellmanir Dieter , Lanzrath Günther , Hüttner Gottfried , Zsolnai Laszlo , Krüger Carl , Claus K. H.
Published: February 2015

Reaction of FeCl3 · 4 H2O with dttd2-, the dianion of 2,3,8,9-dibenzo-1.4,7,10-tetru-thiadecane, leads to the solvated [Fe(dttd)], which coordinates CO, PMe3 and N3H4 yielding [Fe(CO)2dttd], [Fe(PMe3)2dttd], [Fe(CO)PMe3(dttd)], [Fe(N2H4)2dttd] and [Fe(N2H4)CO(dttd), respectively. With H2S and [Fe(dttd)] the Fe(III) complex (PPN)2[Fe2(S)2(dttd)2] is obtained. PPh3 cannot be coordinated to [Fe(dttd)], whereas the reaction between [Fe(PPh3)(CO)3I2] and LiSC6H4SCH3yields [Fe(PPh3)CO(CH3SCeH4S)2] besides the major product [Fe(CO)2(CH3SCeH4S)2]. A PPh3 complex can be obtained also with o-benzenedithiolate, C6H4S2
2-: Reacting [Fe(PPh3)(CO)3I3] with Li2S2C6H4 yields the binuclear [Fe(PPh3)(CO)2C6H4S2]2. Oxidation of [Fe(N3H4)CO(dttd)] by various agents leads to [Fo(CO)dttd]2 without evidence of formation of a N2 complex intermediate. Nucleophilic attack of [Fe(CO)2(CH3SC6H4S)2] by lithium organyls as e.g. LiPh leads to the benzoylato complex [Li(THF)3][Fe(CO)(PhCO)(CH3SC6H4S)2]; the structures of the starting complex as well as of the adduct have been elucidated by X-ray structure determination. Nucleophilic attack of the corresponding [Fe(CO)2dttd] by LiPh occurs reversibly at the Fe center; by cleavage of a Fe-S bond [Fe(Ph)(CO)2dttd′]- is formed, where dttd′ is acting as a tridentate ligand. This result shows how the reactions of formally equivalent complexes like [Fe(CO)2(CH3SC6H4S)2] and [Fe(CO)2dttd] depend strongly upon the denticity of the sulfur ligands. The dependence upon the character of the nucleophilic agent is shown by the reaction of [Fe(CO)2dttd] with Li[BEt3H]; in this case again a CO ligand is attacked reversibly yielding the formyl complex [LiBEt3][Fe(HCO)CO(dttd)], the structure of which could be elucidated so far only spectroscopically as well as by elemental analysis.

[Fe(Ph)(CO)gdttd′]- forms salts like e.g. (AsPh4)[Fe(Ph)(CO)2dttd]; in solution they slowly loose CO yielding e.g. binuclear (AsPh4)2[Fe(Ph)dttd]3. Attempts to isolate the anion as [Li(TMED)3]+ salt load to the loss of CO as well as of phenyl ligands yielding the paramagnetic [Fe(TMED)dttd], which is also obtained directly from [Fe(dttd)] and TMED. The phenyl complex [Fe(Ph)dttd]2
2- is also formed by reaction of [Fe(dttd)] with LiPh; on reaction with dimethyl-formamide it yields [Fe(DMF)dttd]2. A series of the above described compounds has been investigated by Mößbauer spectroscopy.
Preparation and Structures of Ternary Copper(II) Complexes of Purine 3′,5′-Cyclic Nucleotides [1]
Authors: Sheldrick W. S.
Published: February 2015

Ternary copper(II) complexes of 3′,5′-cIMP and 3′,5′-cGMP with o-phenanthroline have been isolated from aqueous solution at respective pH values of 2.8 and 5.8. Their structures have been established by single crystal X-ray diffraction. The copper atom in [Cu(3′,5′-cIMP)(phen)(H2O)2][NO3].2H2O (1) binds N(7) of the hypoxanthine base and displays a square pyramidal coordination. [Cu(phen)2(H2O)]2+ and 3′,5′-cGMP form a 1 : 2 intercalation complex [Cu(phen)2(H2O)][3′,5′-cGMP]2 · 9H2O (2) in which direct metal- nucleotide binding is absent.
Ein einfaches Verfahren zur Herstellung der labilen Stereoisomeren von 5-Benzyliden-pyrrolin-2-onen / A Simple Procedure to Prepare the Labile Stereoisomers of 5-Benzylidenepyrrolin-2-ones
Authors: Stachel Hans-Dietrich , Poschenrieder Hermann , Wiesend Bruno
Published: February 2015

The known Z-isomers of some N-unsubstituted 5-benzylidenepyrrolin-2-ones (2, 10, 12) change the configuration upon heating with oxalylchloride. Methanolysis of the intermediate imides (6, 8, 9) yields the corresponding E-isomers.
Über Naphtho[1.8-de]-1,3-dioxine / Naphtho[1,8-de]-1,3-dioxines
Authors: Daliacker Franz , Jacobs Johannes , Coerver Wim
Published: February 2015

Treatment of 1,8-Dihydroxy-naphthaline with bromochloromethane/K3CO3 in DMF gives Naphtho[1,8-de]-1,3-dioxine (1a) in good yield. The bromo (1b) and nitro compound (1c) can be obtained free of isomorics by electrophilic substitution of la. Bromolithium exchange of 1b leads to a lithium organic compound, which possibles the synthesis of alkyl-, olefinic-, and carboxylic derivatives of the substrate 1a.

In a similar way the treatment of 2,3-dihydroxynaphthazarin with chlorobromomethane/K2CO3 gives the naphtho[1,8-de;4,5-d′e′]-bis-1,3-dioxine (3a). The substrate 3a can be subjected to electrophilic aromatic substitutions.
3-Hydroxy-, 3-Alkoxy-und 3-Amino-2-thioxooxazolidin-4-one aus 6 -Thioxoperhydro -1.5.2-dioxazin-3-onen / 3-Hydroxy-, 3-Alkoxy-and 3-Amino-2-thioxooxazolidine-4-ones from 6-Thioxoperhydro-1,5,2-dioxazine-3-ones
Authors: Geffken Detlef
Published: February 2015

1,1′-Thiocarbonyldiimidazole converts N-substituted glycolohydroxamic acids (1) at room temperature into 6-thioxoperhydro-1,5,2-dioxazino-3-ones (2 B), which are highly reactive heterocyclic compounds. In the presence of primary amines (3), benzyloxyamine (6a), hydroxylamine (6b) and hydrazines (8a-d) ring transformation of 2 B occurs, yielding 2-thioxooxazolidine-4-ones of type 5, 7 and 9.
Structure-Activity Relationships of Polyfunctional Diterpenes of the Tigliane Type, V / Preparation and Irritant Activities of Amino Acid and Peptide Esters of Phorbol
Authors: Marston A. , Hecker E.
Published: February 2015

Tho synthesis of a series of 12-O-amino acyl- and 12-O-peptidyl-13-acetate and -13,20- diacetate esters of the tetracyclic diterpene alcohol phorbol is described. These esters, which include amino acid moieties with both N-protected and free amino functions, were all tested for irritant activity on mouse ear. The highest activities were observed for esters with N-9-fluorenylmethyloxycarbonyl-protected leucine and 11-aminoundecanoic acid.
Study of Hydrogenolytic Cleavage of Peptide-Resin Benzyl Ester Bonds for Synthesis of Protected Fragments of the Human Leukocyte Interferon
Authors: Ljungqvist Anders , Folkers Karl
Published: February 2015

Three Roe-protected fragments of the human leukocyte interferon, LeIFA, have been synthesized: I, BOC LeIFA (99-105) (BOC-Val-Ile-Gln-Gly-Val-Gly-Val); II, BOC Lei FA (116-119) (BOC-Ile-Leu-Ala-Val); III, BOC LeIFA (123-126) (BOC-Phe-Gln-Arg(Tos)-Ile). The presence of the Boc-group was desired so that these peptides could serve as intermediates in fragment condensation toward larger segments of interferon. To achieve these intermediates, a study was desirable on three methods of cleavage of the benzyl ester-polymer bonds. It was found that hydrogenolysis with hydrogen and palla­dium generated in situ was distinctly superior to transfer hydrogenation with ammonium formate or cyclohexene. An effective swelling of the peptide-resin to allow penetration of palladium acetate into the matrix and mobility of the peptide chains on the resin to expose the bonzyl ester bond to hydrogenolysis appear to be essential conditions for the best cleavage.
Notizen: Alkylsubstituierte Diphosphinomethane: Gemischte Cl/t-Bu- und Me/CH2SiMe3-Derivate [1] / Alkyl Substituted Diphosphinomethanes: Mixed Cl/t-Bu and Me/CH2SiMe3 Derivatives [1]
Authors: Karsch Hans H.
Published: February 2015

The syntheses of (t-Bu)2PCH2P(t-Bu)2 and (PhO)2PCH2P(Oph)2 and an improvement of the synthesis of Me2PCH2PMe2 are described. Mixed Me/CH2SiMe3 and Cl/t-Bu diphosphinomethane derivatives are characterized by means of NMR spectroscopy.
Notizen: PPh3Me[O8(NO)Cl4]; ein fünffach koordinierter Osmiumnitrosylkomplex / PPh3Me[Os(NO)Cl4]; a Pcnta Coordinate Osmium Nitrosyl Complex
Authors: Czeska Bernhard , Dehnicke Kurt , Fenske Dieter
Published: February 2015

PPh3Me[Os(NO)Cl4] is prepared by the reac­tion of (NO)2[Os(NO)Cl5] with methyltriphenylphosphonium chloride in CH2Cl2 solution. The complex forms brown, air stable crystals, which are characterized by the IR spectrum as well as by an X-ray structure determination (space group P1̄, two formula units per unit cell, a = 906, b = 1172, c = 1198 pm, α = 76.4, β = 84.8, γ = 82.4°, 3254 independent reflexi­ons, Rw = 8.6%). The structure consists of [P(C6H5)3CH3]⊕ cations and disordered [Os-(NO)Cl4]⊖ anions; the latter have approximate C4V symmetry with a linearly coordinated nitrosyl ligand in the axial position.
Fluorapatit Ca5F(PO4)3 - Ein Modell zur Synthese der Zahnhartsubstanz im System CaF2-Ca3(PO4)2 / Fluorapatite - A Model for the Synthesis of Dental Enamel in the System CaF2-Ca3(PO4)2
Authors: Franz Ernst-Dieter
Published: February 2015

Fluorapatite Ca5F(PO4)3 can be synthesized by melting of CaF2 together with Ca3(PO4)2 at 1660 °C in the molar ratio CaF2 · 3 Ca3(PO4)2. Fluorapatite is more resistant against acids than hydroxylapatite Ca5OH(PO4)2 and can activate the remineralisation in dental enamel. The apatite of dental enamel is more resistant against mechanical stress than synthetic apatite due to a different microstructure of the crystal grains.
Tetrathio -spiro -phosphonia -tetrachloroborateDie Struktur von 1.4.6.9-Tetrathio-5-phosphonia-spiro (4.4) nonan-tetrachloroborat / Tetrahio-spiro-phosphonia TetrachloroboratesThe X-Ray Crystal Structure of 1,4,6,9-Tetrahio-5-phosphonia-spiro(4,4)nonan Tetrachloroborate
Authors: Koblischek Alfred , Hausen Hans-Dieter , Weidlein Johann , Binder Herbert
Published: February 2015

A series of tetrathio-spiro-phosphonia tetrachloroborates have been synthesized by the reaction of PCl4+BCl4
- with 1,2-ethane-, 1,2-propane-and 1,3-propane dithiole. The crystal structure of 1,4,6,9-tetrathio-5-phosphonia-spiro(4,4)nonane tetrachloroborate, 3a, was determined from diffractometer data and refined to R = 0.056 for 4003 independent reflexions. 3a, orthorhombic, Pbcn, a = 1493.0(3), b = 1515.6(3), c = 1213.3(4) pm. The unit cell containes eight formula units.
Cyclische Diazastannylene, XVIII [1]Zur Frage der Bindungsbeschreibung in Polyedern des Typs Sn4X3Y:Die Kristall-und Molekülstrukturen von Sn4(NtBu)4 und Sn4(NtBu)3O / Cyclic Diazastannylenes, XVIII [1]Bonding Description in Polyhedra of the Sn4X3Y-Type:The Crystal and Molecular Structures of Sn4(NtBu)4 and Sn4(NtBu)3O
Authors: Veith M. , Recktenwald O.
Published: February 2015

Crystals of Sn4(NtBu)4 (1) are monoclinic, space group P21/c, with cell constants a = 1038.9(4), b = 1468.3(5), c = 1698.8(5) pm, β = 91.6(1)° and Z = 4, while those of Sn4(NtBu)3O (2) are triclinic, space group P 1̄, with dimensions a = 1293.0(5), b = 1027.1(5), c = 1716.7(9) pm, α = 90.9(1), β = 102.5(1), γ = 107.0(1)° and Z = 4. The molecules 1 are held together by van-der-Waals forces, whereas two molecules 2 interact in the crystal by weak 0→Sn donor bonds (290-332 pm) forming dimers. The outstanding structural elements of 1 and 2 are the Sn4N4 and Sn4N3O polyhedra, which can be described by two interpenetrating tetrahedra of tin atoms and of nitrogen or nitrogen and oxygen atoms forming a distorted cube, which approaches 4̄3 m symmetry in the case of 1 and 3m for 2. Characteristic distances are in 1: Sn-N 220.2 pm, in 2: Sn-N 221.3 pm and Sn-O 213.2 pm. An almost ionic bonding model and two covalent models are discussed on the basis of the structural data including Sn4(NtBu)3OAlMe3.
Siliciumverbindungen mit starken intramolekularen sterischen Wechselwirkungen, XIV [1] Versuche zur Synthese des Tetra-tert-butylsilans: Tri-tert-butylisopropylsilan und verwandte Verbindungen / Silicon Compounds with Strong Intramolecular Steric Interactions, XIV [1] Attempted Synthesis of Tetra-tert-butylsilane: Tri-tert-butylisopropylsilane and Related Compounds
Authors: Weidenbruch Manfred , Flott Hermann , Ralle Bernd , Peters Karl , Schnering Hans Georg von
Published: February 2015

Reaction of tri-tert-butyl(dihalomethyl)silanes (halo = chloro, bromo) with organolithium compounds, by lithium/halogen or lithium/hydrogen exchange, leads to the corresponding carbenoids which by lithium halide elimination could give the carbenes (t-C4H9)3SiCX. Further intermolecular or intramolecular reaction of these reactive intermediates provides a variety of crowded molecules including alkyltri-tert-butylsilanes, 1,2-bis(tri-tert-butylsilyl)- substituted ethanes and ethenes and ring substituted 1,2-di-tert-butyl-1-silacyclo-butanes. An X-ray structure determination of (E)-1,2-bis(tri-tert-butylsilyl)-1,2-dichloroethene reveals neither a twisting nor an elongation of the CC double bond, but the C = C-Si bond angles exhibit rather unusual values (up to 137.7°) and the Si-C (sp2) bonds are as long as 195 pm.

Tri-tert-butylisopropylsilane was prepared by a two step procedure and characterized by its variable temperature NMR spectra. The attempted synthesis of tetra-tert-butylsilane by reactions of the compound with bromine followed by treatment with methyllithium afforded only tri-tert-butylisopropenylsilane.
A New Synthesis of Organodifluorophosphites and their Reactions with Platinum(II) Complexes
Authors: Krüger Wieland , Sell Michael , Schmutzler Reinhard
Published: February 2015

Alkyldifluorophosphites, ROPF2 (R = p-substituted benzyl group, neopentyl, 1-adamantyl) have been obtained by a new method, involving reaction of the appropriate alkyl trimethylsilylether, ROSiMe3 with chlorodifluorophosphine, PF2Cl. Reactions of these difluorophosphites with platinum(II) complexes of the type [L2PtCl2] (L = PEt3, PPh3) led to products such as trans-[L2PtCl(POF2)] and {[p-XC6H4CH2PPh3]+}2[Pt(POF2)4]2-, (X = H, Me, Cl, NO2). The ease of carbon-oxygen cleavage in ROPF2 is characteristically related to the nature of the leaving group, R.
Acid and Polarity Effects in Benzene Photoreactions with Alkenes and Alkynes
Authors: Bryce-Smith D. , Gilbert A. , Al-Jalal N. , Deshpande R. R. , Grzonka J. , Hems M. A. , Yianni P.
Published: February 2015

The effects of polar solvents and proton donors on various photoreactions of the benzene ring with electron-acceptor alkenes and alkynes are described and discussed in relation to the various electronic excitation mechanisms involved. Proton donors prove valuable as mechanistic probes for polar intermediates in such processes, and can in some systems both initiate and divert reaction pathways.
2-Alkoxy-3-hydroxy-1,2-oxaphospholane-2-oxides (α-hydroxyphostones)
Authors: Pilgram Kurt H. , Gale Laird H. , Pollard Glenn E.
Published: February 2015

The addition-cyclocondensation reactions of three β-hydroxyketones with four dialkyl phosphites gave 2-alkoxy-3-hydroxy-1,2-oxaphospholane-2-oxides (“α-hydroxyphostones”) (7), in moderate yields. In the solid state and in solution, these compounds exist as dimers with hydrogen bonding between the hydroxyl group and the phosphoryl oxygen atom of an adjacent molecule. The crystal and molecular structure of 3-hydroxy-2-methoxy-3,5,5-trimethyl-1,2-oxaphospholane-2-oxide (7 a) has been determined by single-crystal X-ray crystallography: C7H15O4P, monoclinic space group P2-1/n, cell dimensions a = 8.087(1) Å, b = 13.386(2) Å, c = 9.306(1) Å, V = 1007.4 Å3 , Z = 4, final R = 0.052. The five-membered ring is puckered, with the carbon bearing the OH and CH3 groups lying out of the plane of the remaining four atoms in the ring. The doubly bonded oxygen attached to the phosphorus atom and the hydroxyl oxygen are in a cis-relationship. The O(1)-O(4) intermolecular bond distance of 2.75 Å suggests hydrogen bonding. The O(1)-H(1) intermolecular bond distance of 1.97 Å is consistent with this conclusion.
Anthraquinones and Anthraquinone Glycosides from the Roots of Cassia multijuga
Authors: Tiwari R. D. , Singh J.
Published: February 2015

From the roots of Cassia multijuga 1:3-dihydroxy-2-methyl anthraquinone, 1:3:8-tri-hydroxy-6-methoxy-2-methyl anthraquinone, 1:8-dihydroxy-6-methoxy-2-methyl an-thraquinone-3-O-rutinoside and 1:8-dihydroxy-2-methyl anthraquinone-3-O-rutinoside have been isolated and their structures elucidated.
In the Search for New Anticancer Drugs, IV+ Antitumor Activity of Seleno-TEPA
Authors: Konieczny Maria , Gutierrez Peter L. , Sosnovsky George
Published: February 2015

In order to test the effect of selenium on the anticancer activity of alkylating drugs, Seleno-TEPA (4), the selenium analog of the clinically used Thio-TEPA (1) was tested in vivo against the lymphocytic P 388 and lymphoid L1210 murine leukemias. Compound 4 is more active against P 388 leukemia than against L1210, and appears to be active over a narrower concentration range than Thio-TEPA (1). Compound 4 is less active against P 388 leukemia than 1, as evidenced by the T/C values of 164 for 4 and 239 for 1 at a dose of 4.2 mg/kg. The activity of 4 was also evaluated on the HL60 and K 562 human cell lines. Under the conditions of the cell colony assay technique, Seleno-TEPA (4) is less effective than Thio-TEPA (1).
In the Search for New Anticancer Drugs, V+ Study of the Binding of Spin-Labeled Thio-TEPA to Cells
Authors: Konieczny Maria , Gutierrez Peter L. , Sosnovsky George
Published: February 2015

The spin labeled analog, SL-O-TT (2), of Thio-TEPA (1) inhibits

the incorporation of 3H-thymidine by 50% (IC50) at a dose of 2.6 × 10-4 M in L 1210 and at a dose of 6 × 10-4 M in P 388 murine leukemias. On the basis of cell fractionation studies, compound 2 was found to bind about qeually to the cell nuclei, microsomes, and mitochondria. ESR experiments indicate different of immobilization of the label in various fractions. The efficiency of binding of 2 to cells appears to be at least 6%.
In the Search for New Anticancer Drugs, VI+ Structural Modifications of Cyclophosphamide
Authors: Sosnovsky George , Paul Buddha D.
Published: February 2015

Taking into consideration the known mechanism of the drug action of cyclophosphamide (1), several analogs and related compounds 5, 6, 7, 9, 11, 12 and 27 were synthesized, and tested against lymphocytic leukemia P 388 in mice.

Moderate to high activity was found with 5 (T/C × 100 = 243 at a dose of 300 mg/kg), 7 (T/C × 100 = 155 at a dose of 55 mg/kg). None of these compounds was found to be more active than 1 (T/C × 100 = 339 at a dose of 65 mg/kg). Although the essential position C 4 for the enzymatic activation is completely blocked in 5, the compound possesses a high degree of activity. This result justifies a reevaluation of the proposed mechanism of drug action of 1 and its analogs.
Bequeme Synthese von cis-1,2- Bis(diphenylphosphino)ethanplatin(II)- acetyliden / Convenient Synthesis of cis-1,2-Bis(diphen3dphosphino)- ethane-platinum (II) -acetylides
Authors: Sebald Angelika , Wrackmeyer Bernd
Published: February 2015

The title compounds (1) are obtained in quantitative yield from the reaction between dppePtCl2 (2) and alkynyl stannanes (CH3)3 Sn - C ≡ C-R (3) or (CH3)2Sn(C ≡ C-R)2 (4) in boiling tetrahydrofurane. The complexes 1 have been characterised by multinuclear NMR (13PC, 31P, 195Pt).
Contribution to the Chemistry of Boron, 136 [1]. A Reinvestigation of the Existence of 1,3,2-Dioxaborinium(1 + ) Cations
Authors: Narula Chaitanya K. , Nöth Heinrich
Published: February 2015

It is shown that the previously reported 1,3,2-dioxaborinium salts containing tricoordinated boron are in fact tetracoordinated coordination compounds. The same holds for the corresponding triflates.
Reaktionen von Mehrfachbindungssystemen mit dem 1.2.4-Trithia-3.5-diborolan-Ring -Eine strukturelle Richtigstellung / Reactions of Multiple-Bond-Systems with the 1,2,4-Trithia-3,5-diborolane Ring - A Structural Correction
Authors: Noltemeyer Mathias , Sheldrick George M. , Habben Carl , Meller Anton
Published: February 2015

The reaction of the 1,2,4-trithia-3,5-diborolane system with alkynes does not give 1,3,2-dithiaboroles, as suggested earlier [1, 2], but the previously unknown 1,2,3-dithiaboroles. With organic isocyanates and di-isopropylcarbodiimide, 1,2-dithia-3-bora-4-azacyclopentanones-( 5) and -thiones-(5), respectively, were isolated. The latter systems are isomers of the 5-methyl-1,4-dithia-2-aza-5-boracyclopentanones-(3) and -thiones-(3), which had been previously assumed as reaction products. The structures of 3-diethylamino-4,5- diphenyl -1,2,3 -dithiaborole - (4) (18), 3-(2,6-dimethylphenyl)-amino-4,5-diethyl-1,2,3-dithiaborole-( 4) (31) and 2-diphenylamino-1,3,2-dithiaborole-(4) (32) have been determined by X-ray diffraction. 18 is monoclinic, space group P21, a = 627.8(2), b = 1218.8(2), c = 1158.6(3) pm, β = 97.35(2)° and Z = 2. 31 is monoclinic, space group C2/c, a = 1475.9(5), b = 898.6(3), c = 2434.7(9) pm, β = 102.71(3)° and Z = 8. 32 is orthorhombic, space group Aba 2, a = 2557.3(8), b = 1748.5(5), c = 935.2(2) pm, Z = 12. 1H, 11B, 13C NMR, mass and IR spectra are also reported and discussed.
Die Struktur vermeintlicher Di-und Triketone des 2.2.6.6-Tetramethylpiperidins: Mono-und Diketone des Pyrrolin-1 / The Structure of Supposed Di-and Triketones of 2,2,6,6-Tetramethylpiperidine: Mono-and Diketones of Pyrroline-1
Authors: Hofmann Peter , Sieber Alexander , Beck Erich , Schubert Ulrich
Published: February 2015

It is shown by X-ray structure determination of its acetyl derivative, that the vic. triketone 2,2,6,6-tetramethylpiperidine-3,4,5-trione reported in the literature really is 2-(1-hydroxy-1-methylethyl)-5,5-dimethyl-4,5-dihydropyrrol-3,4-dione. The UV-PE-spectra of both compounds and their electronic structures are interpreted by means of MO calculations. A mechanism yielding these pyrroline-1 derivatives instead of piperidine ketones is suggested, the formerly assigned structures of precursors are corrected.
Darstellung, Eigenschaften und Kristallstruktur der N-[2-(4.5.6.7-Tetrahydro-2-benzimidazolyl)-ethyl] -phthalamidsäure / Preparation, Properties and Crystal Structure of N-[2-(4.5.6.7-Tetrahydro-2-benzimidazolyl)-ethyl]-phthalamic Acid
Authors: Elz Sigurd , Buschauer Armin , Dräger Martin , Schunack Walter
Published: February 2015

During syntheses using the phthalimide rest in liquid, ethanolic or aqueous ammonia, phthalamides, phthalimides or phthalamic acids are formed depending on reaction condi-tions and work-up. As demonstrated by the synthesis of the title compound via hydrolysis of 4 with aqueous ammonia, dipolar ions of phthalamic acids are obtained if the phthal-imide-N substituent is sufficiently basic. The crystal structure of 5 • 4H2O has been determined and refined until R = 0.0878. It shows a vast system of hydrogen bonds.
Argon-Matrix Isolation of Bis(carbomethoxy)thiirene: Formation of Acyl and Carbalkoxythioketenes
Authors: Torres M. , Clement A. , Strausz O. P.
Published: February 2015

Photolysis of argon-matrix isolated 4,5-bis(carbomethoxy)-1,2,3-thiadiazole with λ = 254 or 265 nm resulted in the almost quantitative formation of bis(carbomethoxy)-thiirene (3g). Photolysis of 3g could only be carried out by long irradiation times at short wavelength λ = 210 nm and resulted mainly in extensive fragmentation instead of the formation of bis(carbomethoxy)thioketene, confirming earlier predictions that substituents, especially electron-withdrawing ones, should stabilize the thiirene ring. Methylcarboethoxy and methylacetylthioketene were obtained, however, in the argon-matrix photolysis or flow thermolysis of 4-methyl-5-carboethoxy-or 4-carboethoxy-5-methyl-1,2,3-thiadiazole and 4-acetyl-5-methyl-1,2,3-thiadiazole, respectively.
Nematogens for Matrix-Addressed Twisted Nematic Displays, II
Authors: Osman Maged A. , Huynh-Ba T.
Published: February 2015

Nonpolar aromatic nematogens useful in mixtures for high performance matrix-addressed twisted nematic displays were synthesized. Nematic phases were obtained by introducing lateral halo-substituents in purely smectic biphenyls and phenyl pyrimidines. Because of their chemical stability, low viscosity and negative dielectric anisotropy, the substituted biphenyls can also be used in mixtures of negative dielectric anisotropy which are needed for the homeotropic nematic and guest-host displays with positive contrast. The effect of lateral halo-substituents on the mesomorphic properties of rod like molecules is discussed.
Die Elektronenaffinität der Halogene ermittelt aus elektrochemischen und kalorimetrischen Messungen / The Electron Affinity of the Halogens Determined from Electrochemical and Calorimetrical Measurements
Authors: Stanienda Alfred
Published: February 2015

Using a conception given in [1, 3] for single ionic solvation and redox reactions the electron affinities (EA) of halogens are calculated from calorimetric data of their reactions with methyleneblue radical giving the values 8.81 eV; 8.23 eV; and 7.16 eV for Cl, Br and I, respectively. For iodine EA is also obtained from the reaction enthalpy of the reaction between iodide and Mg-porphyrine cation radical. EA calculated from electrochemical standard potentials are only approximately 0.2 eV higher than found from calorimetric data except for iodine, the standard potential of which could be influenced by I3-. The disagreement of the EA values given in the literature and those presented in this work is mainly caused -to the author's opinion -by a different interpretation of single ionic solvation and the size of ionic radii in solutions.

From experimental data [1,3] solvation of anions is regarded as an energy consuming process which is understood as the overall repulsion between the anionic charge and the outer sphere electrons of solvent molecules. For calculation of the solvation energy according to the Born equation different radii have to be used: in the case of anions, the radius is composed of the radius of anions in the crystals extended by the average radius of a solvent molecule, in the case of cations -the solvation of which is an energy supplying process -the radius of atoms must be taken. On this basis the ionisation energy of tetra-methyl-p-phenylenediamine is calculated from calorimetric data for the reaction with bromine. As other examples the reaction enthalpies of the reactions of chlorine with methyleneblue radical, Li, Na, K, Cs, Be, Ca, La, Al and Zr are calculated in the gas phase as well as in water and compared with experimental ⊿G-values obtained from electrochemical standard-potentials. Excellent agreement for all selected examples is found. The discussion includes electron absorption energies of anions and solvation of ionic crystals in a solvent.
Meso -Tetraalkyl-Porphyrine / Meso-Tetraalkyl-Porphyrins
Authors: Volz Heinrich , Herb Georg
Published: February 2015

Alkyl-pyrryl-carbinols are cyclised in acidic medium to meso-tetraalkyl-porphyrins.
Chirale Erkennung von Naturstoffen an optisch aktiven Polysiloxanen Chiral Recognition of Natural Products on Optically Active Polysiloxanes
Authors: Bayer Ernst
Published: February 2015

Polysiloxanes with chiral peptide side chains have been synthesized and used as stationary phases in gas chromatography. With these phases amino acid enantiomers can be separated as N-acyl esters. Due to temperature stability up to 230 °C all protein amino acids can be separated and the racemization of synthetic biologically active peptides controlled. The phases can be used to assign the absolute configuration of amino acids. A variety of other classes of compounds can be separated into their enantiomers using the chiral polysiloxanes, like hydroxy acids, sulfoxides, phosphorous compounds, glycols, atrop isomers, amines and alcohols. Various applications of these phases are described including investigations of enantiomer selectivity in nature.
Notizen: Eine verbesserte Synthese für Bis(trimethylsilyl)magnesium / An Improved Synthesis of Bis (trimethylsilyl)magnesium
Authors: Rösch Lutz , Starke Uwe
Published: February 2015

Mg(SiMe3)2 · DME can be prepared in high yields by reaction of magnesium powder with Hg(SiMe3)2 in 1,2-dimethoxyethane in a supersonic bath.
Notizen: Die Kristallstruktur von Tetraphenylphosphoniumnitridotetrachloromolybdat PPh4[MoNCl4] / The Crystal Structure of Tetraphenylphosphonium Nitridotetrachloromolybdate PPh4[MoNCl4]
Authors: Müller Ulrich , Schweda Eberhard , Strähle Joachim
Published: February 2015

PPh4[MoNCl4] is isotypic with AsPh4[MoNCl4], crystallizing in the space group P4/n. The lattice constants a = 1277.6 and c = 765.4 pm are slightly smaller for the PPh4
+ salt; the difference can be explained by the shorter bond lengths P-C vs. As-C. The conformation angles of the phenyl groups are nearly equal in both compounds.
Notizen: Electronegativity Order of Group IV Elements: Evidence from Molecular Geometry
Authors: Hargittai Istvan , Bliefert Claus
Published: February 2015

Electronegativities, Group IV Elements Electronegativities for Group IV elements A have been estimated from the bond lengths observed in AX2 and AX4 molecules (X = F, Cl, Br). The order of electronegativities established by this method is χC > χGe > χsn > χSi.
Notizen: The Isolation and Structure of Hyderabadine, a New Indole Alkaloid from Ervatamia coronaria
Authors: Atta-ur-Rahman  , Daulatabadi Nader
Published: February 2015

A new indole alkaloid, hyderabadine, has been isolated from the leaves of Ervatamia coronaria to which structure 1 has been assigned.
Synthese, Molekül-und Elektronenstruktur eines Radikal-Kationkomplexes [Cr(CO)4(Carben)2]+ / Synthesis, Molecular and Electronic Structure of a Radical Cationic Complex [Cr(CO)4(Carbene)2]+
Authors: Ackermann Klaus , Hofmann Peter , Köhler Frank H. , Kratzer Hans , Krist Herbert , Öfele Karl , Schmidt Helmut R.
Published: February 2015

A new one-step synthesis for bis-carbene complexes cis-M(CO)4L2 (M = Cr, Mo, W) containing cyclic carbene ligands L has been developed. These compounds can be oxidized by ferrocenium salts to paramagnetic cation complexes [M(CO)4L2]+ which, for M = Cr, are isolable in the form of their PF6 salts. The chromium compounds with L= 1,3-dimethyl-4-imidazolin-2-ylidene permit for the first time a structural and spectroscopic comparison of a diamagnetic carbene complex with the corresponding paramagnetic cation; the experimental facts are interpreted by molecular orbital calculations.
Amino(keto)carbene und Amino(phenyl)carbene als 1.4-dipolare Brückenliganden in einer Fe2(CO)6-Matrix / Amino(keto)carbenes and Amino(phenyl)carbenes as 1,4-Dipolar Bridging Ligands in a Fe2(CO)6 Matrix
Authors: Aumann Rudolf , Heinen Heinrich , Henkel Gerald , Dartmann Mechtild , Krebs Bernt
Published: February 2015

Cyclohexylamino(keto)carbene complexes of group VI B metals which contain a terminally bound carbene ligand, on reaction with Fe2(C0)9 give binuclear oxallyl iron complexes 5, in which the carbene carbon and the keto function form a bridge consisting of three atoms bound to two iron atoms. From a single crystal structure analysis of the phenyl derivative 5b, the Fe-Fe distance was found to be 2.508 Å. The two C atoms are bridging the Fe2 group in a somewhat distorted manner (C(l)-Fe(l) 2.461, C(l)-Fe(2) 1.912, C(2)-Fe(l) 2.024, C(2)-Fe(2) 2.478 Å), whereas the bridging keto oxygen is symmetrically bound to both Fe (1.927 and 2.004 Å).

Alkylamino(phenyl)carbene complexes like 11 react with Fe2(C0)9 to give a four atom bridging ligand by migration of a hydrogen atom from nitrogen and an ortho hydrogen from the phenyl group to the carbene carbon. Free or complexed alkylimines may be intermediates in this reaction.
Structure of a Pt(II)-Pt(IY) Mixed-Valence Linear Chain Complex: Bis (1,2-diaminopropane )platinum(II)bis (1,2-diaminepropane ) - dibromoplatinum(IV)tetraperchlorate
Authors: Cannas M. , Marongiu G. , Martin R. , Keller H. J.
Published: February 2015

[Pt(C3H10N2)2][Pt(C3H10N2)2Br2](ClO4)4 crystallizes as flat orthorhombic needles with cell dimensions: a = 7.74(1); b = 11.14(2); c = 19.42(3) Å, Z = 1. Since rotation photo­graphs showed diffuse patterns corresponding to odd values of k without any Bragg reflections, the subcell for which b = 5.57(1) Å was adopted for the structural analysis; it has systematic absences consistent with space groups Pc 2 a and Pcma; the structure was refined in both space groups by least squares and difference Fourier syntheses to R = 0.062 in Pc 2a and R = 0.064 in Pcma. A final decision between the two space groups proved to be impossible within the scope of the experiment. An analysis of the “diffuse” layers reveals that the bridging bromines vibrate in a one-dimensional collective mode within a lattice of “uniform”, fixed platinum cations.
Vitamin-Synthesen mit Carben-Komplexen, III [1]. Stereospezifische Synthese von Alkenylcarben-Komplexen des Chroms / Vitamin Syntheses via Carbene Complexes, III [1]. Stereospecific Synthesis of Alkenylcarbene Chromium Complexes
Authors: Dötz Karl Heinz , Kuhn Werner , Ackermann Klaus
Published: February 2015

Addition of lithioalkenes to hexacarbonylchromium followed by alkylation with trimethyloxonium tetrafluoroborate provides a stereospecific route to pentacarbonyl-[alkenyl(methoxy)carbene]chromium complexes. For the E-butenylcarbene complex an approximately orthogonal dihedral angle between the carbene and the alkene plane is established by X-ray analysis.
Metall-π-Komplexe von Benzolderivaten, XX [1]. Über die Cokondensation des Phenanthrens mit Chromatomen - Reaktivität, Redoxverhalten, ESR-und NMR-spektroskopische Untersuchungen / Metal-π-Complexes of Benzene Derivatives, XX [1]. Cocondensation of Phenanthrene with Chromium Atoms - Reactivity, Redox Behavior, ESR and NMR Spectroscopic Investigation
Authors: Eischenbroich Christoph , Bilger Edgar , Möckel Reinhart
Published: February 2015

Cocondensation of chromium atoms with phenanthrene vapor affords bisη1,2,3,4,10a,4a- phenanthrene)chromium (4). 1 NMR spectroscopy reveals, that the diastereomers 4 (rac) and 4' (meso) are formed in a 2:1 ratio. Cyclic voltammetric studies on 4 show, that four oxidation states are accessible:

[E° ═ -2.235 (rev.), -0.651 (rev.), + 0.82 (irrev.) V vs. SCE]. The radical ions

are characterized by ESR spectro­scopy in fluid and rigid solutions. Prominent feature of these species is the inverse relative magnitude of the g-tensor components:

.
Derivate des Borols, IV [1]. Ein Borol-Dianion durch Lithiierung von 1-Diisopropylamino-3-borolen / Derivatives of Borole, IV [1]. A Borole Dianion via Lithiation of 1-Diisopropylamino-3-borolene
Authors: Herberich Gerhard E. , Ohst Holger
Published: February 2015

1 -Diisopropylamino-3-borolene is readily lithiated by tert-butyllithium in THF to produce lithium (1-diisopropylaminoborolenediide), the second known example of the 6 π-electron borole dianion. Trimethylsilylation of the dianion gives trans-1-diisopropylamino-4,5-bis(trimethylsilyl)-2-borolene. Reaction with [{C6(CH3)6}RuCl2]2 affords the (borole)-ruthenium complex [C6(CH3)6]Ru[C4H4BN{CH(CH3)2}2].
Übergangsmetall-Methylen-Komplexe, LI [1]. Carbocyclische Carbene, Carben-Brücken, kleine Kohlenwasserstoff-Liganden und Metallacyclen: Beispiele einer umfassenden Synthesekonzeption / Transition Metal Methylene Complexes, LI [1]. Carbocyclic Carbenes, Carbene Bridges, Small Hydrocarbon Ligands, and Metallacycles: Examples of a General Synthetic Concept
Authors: Herrmann Wolfgang A. , Plank Johann , Hubbard John L. , Kriechbaum Gangolf W. , Kalcher Willibald , Koumbouris Basile , Ihl Gabriele , Schäfer Adolf , Ziegler Manfred L. , Pfisterer Heike , Pahl Claudia , Atwood Jerry L. , Rogers Robin D.
Published: February 2015

Carbene transfer from aliphatic diazoalkanes upon coordinatively unsaturated metal centers is a general synthetic concept that provides straight-forward routes into organo-metallic hydrocarbon chemistry. A comparison focussing on several key reactions of general applicability demonstrates that mononuclear organometal substrates add carbenes that may act as bridging ligands (e.g., compound 6) if they arise from ω,ω'-bisdiazoalkanes. By way of contrast, metal-metal double bonds cleanly form dimetallacyclo-propane-type derivatives under very mild conditions (7-9). The broadest variety of structures is finally encountered with metal-metal triply bonded precursors such as the molybdenum compounds 3: here, the initial diazoalkane adducts are subject to further rearrangement processes commonly leading to metal-metal single bonds (11) or causing irreversible cleavage of the dinuclear metal systems (10).
Funktionelle Trimethylphosphanderivate, XVIII [1]. Methyl(phosphinomethyl)silane und -stannane / Functional Trimethylphosphane Derivatives, XVIII [1]. Methyl(phosphinomethyl)silanes and -stannanes
Authors: Karsch Hans H. , Appelt Armin
Published: February 2015

Mono-and polydentate phosphanes Me(4-x)E(CH2PMe2)x (E = Si, Sn) are prepared by the reaction of LiCH2PMe2 with Me(4-x)EClx. They are easily deprotonated at the methylen carbon atom. The preparation of BrCH2CMe2CH2PMe2 and Me2C(CH2PMe2)2 is also described. The complex formation ability is shown by the isolation of the tetrahedral nickel(0) complex [Me2Si(CH2PMe2)2]2Ni, where the diphosphane acts as a bidentate chelating ligand with heteroelement bridges. The new compounds are characterized by means of NMR spectroscopy.
Oberflächenverbindungen von Übergangsmetallen, XXV [1]: Redoxreaktionen von Oberfläehen-Chrom(II) auf Silicagel mit Olefinen / Surface Compounds of Transition Metals, XXV [1]: Redox Reactions of Surface Chromium(II) on Silicagel with Olefins
Authors: Krauss Hans-Ludwig , Hums Erich
Published: February 2015

Olefins may react with chromium(II)/silicagel catalysts at temperatures from 100 to 600 °C under formation of C1-C4 n-alkanes and organometallic species; the chromium is oxidized simultaneously. By this reaction the catalytic sites loose the ability for olefin polymerization and 〈CH2〉 transfer.

A following treatment of the catalyst with hydrogen at 400 °C produces a second crop of alkanes from former organometallic species under partial reduction of the chromium back to CrII ; the polymerization activity is restorted correspondingly.