bluuebunny/crossref_metadata_2025 huggingface dataset:
Bis(methylen)phosphorane — Synthese, spektroskopische Untersuchungen und thermische Isomerisierungen zu λ3‐Phosphiranen
Authors: Becker Petra , Brombach Heike , David Gabriele , Leuer Martina , Metternich Hans‐Jürgen , Niecke Edgar
Published: July 2007

Bis(methylene)phosphoranes – Synthesis, Spectroscopic Investigations and Thermal Isomerizations to λ3‐Phosphiranes

A great number of differently substituted bis(methylene)phosphoranes 10 [R – P{ = C(SiMe3)2}2] are obtained by nucleophilic substitution from bis[bis(trimethylsilyl)methylene]‐chlorophosphorane (8). The reactions of dichlorophosphanes 1 and methylenephosphanes 3 with lithium carbenoides 2 furnish the mixed derivatives 6 [R—P( = CR1R2)( = CR3R4)] and 7 [R—P( = C(SiMe3)2( = CR3R4)]. Among these the reaction of the sterically less hindered methylenephosphanes 3c, d [R2N—P = C(H)SiMe3, R = Et, iPr] with an excess of the lithium carbenoide 2b results in the formation of the σ4λ5‐phosphiranes 11a, b {R2N – P[ = C(H)SiMe3]2}. The sterically highly demanding substituents in 10a – o render great thermal stability, while the mixed bis(methylene)phosphoranes 6, 7 rearrange to the corresponding σ4λ5‐phosphiranes 15a–o. Investigations performed between 30 and 180°C reveal that all bis(methylene)phosphoranes, with the exception of 6c, k – m and 7e, can be isomerized. – The phosphino‐substituted bis(methylene)phosphoranes 10k, 1 show different reactivity. Light‐and thermally induced cleavage of the P – P bond, and dimerization of the corresponding fragments result in the formation of 14 and the diphosphanes 13a, b. The bis(methylene)phosphoranes 10a–o are investigated by UV and NMR spectroscopy.
Synthese und Strukturen von (Monoorganyl)amiden und ‐imiden des Zirkoniums und Hafniums
Authors: Bai Yüniu , Roesky Herbert W. , Noltemeyer Mathias , Witt Michael
Published: July 2007

Synthesis and Structures of (Monoorganyl)amides and ‐imides of Zirconium and Hafnium

The tetrahalides MCl4 (M = Zr 1 a, Hf 1 b) react with LiNHtBu with elimination of LiCl to yield [(tBuNH)2MNtBu]2 (3) (M = Zr 3a, Hf 3b). Compounds 3 are thermally instable and oli‐gomerise above 100 °C with elimination of H2NtBu. The reactions of (η5‐C5Me5)MCl3 (M = Zr 1 c, Hf 1 d) with LiNHR (R = tBu 2 a,2,4,6‐Me3C6H2 2 b, 2, 6‐iPr2C6H3 2 c) lead to (η5‐C5Me5)M(NHR)3 (4) (R = tBu, M = Zr 4 a, Hf 4 b; R = 2, 4,6‐Me3C6H2, M = Zr 4 c, Hf 4 d; R = 2,6‐iPr2C6H3, M = Zr 4 e, Hf 4 f). Compounds 4 are thermally very stable and melt without decomposition. When 1 c and 1 d react with LiNHPh (2 d), dimers of composition [(η5‐C5Me5)M(NHPh)NPh]2 (M = Zr 5 a, Hf 5 b) are obtained. The complexes (η5‐C5Me5)2MCl2 (M = Zr 1 e, Hf 1 f) react with 2 b to form (η5‐C5Me5)2M(NHR)2 (6) (M = Zr 6 a, Hf 6 b). Pyridine reacts with 4 e at 85 °C and replaces one molecule of 2,6‐iPr2C6H3NH2 to give (η5‐C5Me5)Zr‐(NHR)NR · Py (7). The single crystal X‐ray structures of 4 a, 4 f, 5 b and 7 are described.
Triazolines, XXXI[1] Reaction of 5‐Amino‐4,5‐dihydro‐4‐methylene‐1H‐1,2,3‐triazoles with Substituted Thiazolium‐4‐olates
Authors: Cavalleri Paolo , Clerici Francesca , Erba Emanuela , Trimarco Pasqualina
Published: July 2007

The cycloaddition reaction of 5‐amino‐v‐triazolines 2 with thiazolium‐4‐olates 1 affords two isomeric cycloadducts 3 and 4. A synthetic utilization has been achieved by their desulfuration: The cycloadducts 3 and 4 are catalytically transformed with Raney nickel to pyridinones 5. The acid‐catalized rearrangement of 3 and 4 affords the 8‐thia‐6‐azabicyclo[3.2.1]‐octane derivatives 6.
4,4′‐Distyrylazobenzol als Chromophor
Authors: Meier Herbert , Kosteyn Frank , Hanold Norbert , Rau Hermann , Gauglitz Günter
Published: July 2007

4,4′‐Distyrylazobenzene as Chromophore

4,4′‐Distyrylazobenzenes are prepared from 4,4′‐dimethylazobenzene. Whereas the Siegrist method furnishes stereoselectively the (E,E,E) configuration, a Wittig olefination leads to a mixture of (Z,E,Z), (Z,E,E) and (E,E,E) isomers which can be easily separated. Irradiation of the intense absorption at λ ≈ 400 nm causes a selective (E) → (Z) isomerization of the N = N bond of all three isomers. The reverse reaction takes part in the photochemical equilibration, moreover, it is a thermal process with a relatively low activation barrier.
Remarkable Effect of Fluorine and Chlorine Atoms on the Stability of 1H‐Phosphirene
Authors: Nguyen Minh T. , Vansweevelt Hans , Vanquickenborne Luc G.
Published: July 2007

Ab initio MO calculations at the MP4/6–31G** level show that both fluorine and chlorine atoms exert a strong stabilizing effect on the three‐membered ring 1H‐phosphirene relative to its isomers. While unsubstituted 1H‐phosphirene (12H) is the least stable C2H3P isomer, 1‐fluoro‐1H‐phosphirene (12F) is calculated to be the global minimum of the C2H2FP potential energy surface; 1‐chloro‐1H‐phosphirene (12Cl) is the third most stable of the six C2H2ClP isomers calculated. The remarkable stability of 12F is attributable to the particular strength of the P—F bond.
Synthesis and Methylation of Two Differently Fused Benzologs of Pyrido[1,2‐b]pyridazinium‐4‐olate
Authors: Tímári Géza , Hajós György , Bátori Sándor , Messmer András
Published: July 2007

The alkylation of the two differently fused tricyclic zwitterions 3 and 5 was compared. The linear system 3 was converted into the N‐methyl salt 4 on treatment with dimethyl sulfate and into the O‐methyl product 12 on treatment with Meerwein's reagent. The angular system 5, in turn, was predominantly transformed into the O‐methyl product 14. Theoretical considerations on modified FMO treatment taking into account the lone‐pair densities (cn‐HOMO) suggested that linear 3 was methylated only at the oxygen position (affording 12) and 4 is a thermodynamically controlled remethylation product. A critical interpretation of cn‐HOMO vs. c‐HOMO is discussed.
Stereoselektivität von Photocycloadditionen, 5[1] Photoreaktionen zwischen 2‐Cyclopenten‐1‐on und Enolethern
Authors: Griesbeck Axel G. , Stadtmüller Stefan , Busse Holger , Bringmann Gerhard , Buddrus Joachim
Published: July 2007

Stereoselectivity in Photocycloaddition Reactions, 5[1]. – Photoreaction of 2‐Cyclopenten‐1‐one with Enol Ethers

The regio‐ and stereoselectivity of [2 + 2] photocycloaddition reactions between 2‐cyclopenten‐1‐one (1) and the electron‐rich alkenes: ethyl, isopropyl, and phenyl vinyl ether (2–4) as well as 2,3‐dihydrofuran (10) were examined. In all cases the annulated cyclobutene derivatives 5–7 and 11 were isolated in yields between 70 and 99%. The regioisomeric HT/HH products were formed in a ratio of 3:1 to 4:1. For the determination of the product stereochemistry, INADEQUATE and 1H,1‐decoupling experiments were performed. Computer‐assisted investigations on the molecular geometry and 1H,1H‐coupling constants were performed by using semiempirical methods (AM1, FINITE). The HT regioisomers were formed with moderate endo diastereoselectivity, whereas in the case of the HH regioisomers both diastereomers (exo/endo) were formed in equal amounts. Photoreaction with 2,3‐dihydrofuran (10) led to almost exclusive formation of exo‐diastereomeric HH and HT regioisomers 11. The observed stereoselectivity is rationalized by the optimal geometry of the intermediate triplet 1,4‐biradicals during intersystem crossing.
2,6‐Dicyansemibullvalen
Authors: Quast Helmut , Janiak Rolf , Peters Eva‐Maria , Peters Karl , Schnering Hans Georg Von
Published: July 2007

2,6‐Dicyanosemibullvalene[1]

Bicyclo[3.3.0]octane‐2,6‐dione (2) adds trimethylsilyl cyanide under catalysis by zinc iodide to afford a mixture of the diastereomeric O‐trimethylsilyl cyanohydrins exo,endo‐ and exo,exo‐3 (3:7). Treatment of this mixture with the hydrogen fluoride‐pyridine complex in phosphorus oxychloride as solvent and subsequent heating with an excess of pyridine yield 70% of a 1:1 mixture of the unsaturated dinitriles 4 and 5, which is separated by medium‐pressure liquid chromatography. Allylic bromination of 4 by N‐bromosuccinimide results in the formation of the Y,Y'‐dibromodinitrile 6, the configuration of which is elucidated by means of an X‐ray diffraction analysis. Reduction of 6 with the zinc‐copper couple in tetrahydrofuran under ultrasonic irradiation leads to dilute solutions of the title compound 1 a. Attempts at the isolation of 1 a were frustrated by its tendency to polymerize. The structure of 1 a is based on IR, UV, 1H‐ and 13C‐NMR spectra and a comparison with the known 1,5‐dimethylsemibullvalenedicarbonitrile (1 b).
Paterno‐Büchi Reaction of 2‐Morpholinoacrylonitrile with Benzil
Authors: Döpp Dietrich , Memarian Hamid Reza , Fischer Michael Alexander , Van Eijk Alexander M. J. , Varma Cyril A. G. O.
Published: July 2007

In the lowest excited triplet state, benzil (1) adds highly regio‐ and stereoselectively to the olefin 2‐morpholinoacrylonitrile (2) to form solely the oxetane 5.
Synthese und Kristallstrukturen von Carbonyleisen‐ und Cyclopentadienyleisen‐Zweikernkomplexen des 2,3‐Diethyl‐1,4‐dihydro‐1,4‐dimethyl‐1,4‐diboranaphthalins
Authors: Schulz Hartmut , Pritzkow Hans , Siebert Walter
Published: July 2007

Synthesis and Crystal Structures of Carbonyliron and Cyclopentadienyliron Dinuclear Complexes of 2,3‐Diethyl‐1,4‐dihydro‐1,4‐dimethyl‐1,4‐diboranaphthalene*

Reactions of the 1,4‐Diboranaphthalene derivative 1a with (CO)3Fe(C8H14)2 lead to the orange anti dinuclear complex [(CO)3Fe(η6, η4‐1a)Fe(CO)3] (4a) and to the cherry‐red syn complex [(CO)3Fe(η4, η61a)Fe(CO)2] (5a). The X‐ray structure of 5a reveals an Fe—Fe interaction (2.98 Å), 1a reacts with [(C5H5)Fe(C8H12)]2Zn to give the 30‐VE triple‐decker 7a, in which the diene of the benzo ring can be complexed with a Fe(CO)3 moiety to yield the trinuclear complex 9a.
Synthesis and Reactivity of Mixed Arene Halides of Niobium(I). Crystal and Molecular Structure of Nbmes2 and [Nbmes2(CO)][Nb2(μ‐I)3(CO)8]
Authors: Calderazzo Fausto , Pampaloni Guido , Rocchi Lucia , Gingl Franz , Strähle Joachim
Published: July 2007

Bis(mesitylen)niobium(0), Nbmes2, prepared via the NbCl5/Al/AlCl3/mes system by exaustive reduction in the presence of 1,2‐dimethoxyethane or tetrahydrofuran as previously reported, has been studied by X‐ray diffraction methods. The sandwich molecule has parallel, substantially planar, aromatic rings, in an eclipsed conformation. Nbmes2 is oxidized to Nbmes2X by reaction with 1,1‐dimethyl‐4,4′‐bipyridinium halides [methylviologen halides, mvX2 (X = Cl, I)]. The reaction of both halo compounds with CO yielded the niobium(I) derivatives [Nbmes2(CO)] [Nb2(μ‐X)3(CO)8]. In the case of X = I an IR study at low temperature has shown the presence of intermediate carbonyl compounds, presumably Nbmes2I(CO) and [Nbmes2(CO)]+. The ionic iodide derivative was shown by X‐ray diffraction methods to consist of discrete [Nbmes2(CO)]+ cations and [Nb2(μ‐I)3(CO)8]‐ anions. The two mesitylene groups in the cation are bent and in an eclipsed conformation.
Metallkomplexe mit funktionalisierten Schwefel‐Liganden, III. Reaktionen von (Ph3P)2Pt(η2‐C2H4) mit acyclischen und cyclischen Thiosulfinaten: Platin(II)‐thiolato‐Komplexe mit Sulfenato‐Liganden. Kristallstrukturanalyse von (4‐Sulfido‐1‐butansulfenato‐S,S′)‐bis(triphenylphosphan)platin(II)
Authors: Weigand Wolfgang , Bosl Gabriele , Robl Christian , Amrein Walter
Published: July 2007

Metal Complexes of Functionalized Sulfur‐Containing Ligands, III[1]. – Reactions of (Ph3P)2Pt(η2‐C2H4) with Acyclic and Cyclic Thiosulfinates: Platinum(II)‐thiolato Complexes with Sulfenato Ligands. Crystal Structure Determination of (4‐Sulfido‐1‐butanesulfenato‐S,S′)bis(triphenylphosphane)platinum(II) magnified image

Oxidative addition of acyclic thiosulfinates R′–S(O)–S–R (1a: R′ = R = CH3; 1b: R′ = R = Ph; 1c: R′ = R = p‐CH3C6H4;1d: R′ = p‐ClC6H4, R = C6H5) to (Ph3P)2Pt(η2‐C2H4) (4) leads to the monomeric trans‐configurated complexes (Ph3P)2Pt[S(O)R′](SR) (5a–d) which loose one PPh3 ligand in solution and form the dimetallic thiolato‐bridged compounds [(Ph3P)Pt[S(O)R′](μ‐SR)]2. The cyclic thiosulfinates 1,2‐dithiane S‐oxide (2) and 1,4‐dihydro‐2,3‐benzodithiine S‐oxide (3) react with 4 to yield the monomeric seven‐membered chelate magnified image(7) and the dimetallic complex [(Ph3P)Pt–S(O)–CH2–C6H4–CH2–μ‐S]2 (8), respectively. In 7, characterized by X‐ray diffraction, a tetrahedral distortion of the square planar coordination of the platinum(II) atoms is remarkable; the planes Pt,P(1),P(2) and Pt,S(1),S(2) form an angle of 16.1°.
Isocyanid‐ und Heteroallen‐verbrückte Metallkomplexe, IX. Di‐ und Trieisenkomplexe mit funktionellen Isocyanidbrücken
Authors: Christian Götz , Lentz Dieter , Hartl Hans , Fehlhammer Wolf Peter
Published: July 2007

Isocyanide‐ and Heteroallene‐Bridged Metal Complexes, IX[1,2]. – Di‐ and Triiron Complexes with Functional Bridging Isocyanides

The reactions of ten mainly functional isocyanide dichlorides RN = CCl2 with Na[FeCp(CO)2] in tetrahydrofuran give mono‐isocyanide derivatives [Fe2(Cp)2(CO)3CNR] (1 a–g) of [Fe‐Cp(CO)2]2 in which the isocyanide occupies a bridging position. In three cases also minor amounts of diisocyanide complexes [FeCp(μ‐CNR)CO]2 (2c, 2e, 8) have been isolated. The chlorocarbonyl‐substituted aryl isocyanide dichlorides and pentafluorophenyl isocyanide dichloride in addition suffer (CO)Cl/ and F/ metal exchange, respectively, with formation of μ3‐isocyanide‐bridged triiron complexes (4 a–c, 7) via the intermediates 5 and 6, 7 has been studied by X‐ray analysis.
Monomere und dimere 1,3‐Diaza‐2‐phosphaallyllithium‐Komplexe: Strukturen und ambidente Reaktivität
Authors: Detsch Ralph , Niecke Edgar , Nieger Martin , Schoeller Wolfgang W.
Published: July 2007

Monomer and Dimer 1,3‐Diaza‐2‐phosphaallyllithium Complexes: Structures and Ambident Reactivity*

Metallation of the NH‐functional amino(imino)phosphanes Mes*NPNHR (R = CPh3, Ad, tBu) 1a–c yields the 1,3‐diaza‐2‐phosphaallyllithium compounds 2a–c. The crystal structure shows an ether‐stabilized monomer of 2a and a solvent‐free dimer with an eight‐membered ring in the case of 2b, c. The reaction of 2b with chlorodiphenylphosphane yields, dependent on the reaction conditions, (phosphanylamino)iminophosphane 3 or bis(imino)phosphanylphosphorane 4. The structural and reactivity is discussed on the basis of ab initio calculations.
Mehrstufige reversible Redoxsysteme, LVIII. 2,5‐Bis(cyanimino)‐2,5‐dihydrothieno[3,2‐b]thiophene – ein neuer Acceptortyp: Synthese und allgemeine Eigenschaften
Authors: Günther Erhard , Hünig Siegfried
Published: July 2007

Multistep Reversible Redox Systems, LVIII[1]. – 2,5‐Bis(cyanoimino)‐2,5‐dihydrothieno[3,2‐b]thiophenes – a New Acceptor Type: Synthesis and Common Properties

The synthesis of a variety of substituted 2,5‐bis(cyanoimino)‐2,5‐dihydrothieno[3,2‐b]thiophenes (4) and the corresponding diones (5) is described. Different substituents on the acceptors 4 and 5 allow the redox potentials of these reversible two‐step redox systems to be varied over a wide range.
Epoxidation of Enamines by Dimethyldioxirane: Formation of 1,4‐Dioxanes by Enamine Epoxide Dimerization
Authors: Adam Waldemar , Peters Eva‐Maria , Peters Karl , Schnering Hans Georg Von , Voerckel Volkmar
Published: July 2007

The 1,4‐dioxanes 3a–f, which constitute dimers of the enamine epoxides 2a–f, were obtained in excellent yields as crystalline products during the oxygen transfer to the corresponding enamines by dimethyldioxirane (DMD) in acetone. In methanol at –78°C, enamine 1b gave with dimethyldioxirane the β‐hydroxy acetal 4b as the expected trapping product of the intermediary enamine epoxide 2b.
Stabilisierung von Uran(IV)‐Alkylen durch raumerfüllende Chelatliganden: Molekülstruktur von [PhC(NSiMe3)2]3UMe
Authors: Wedler Michael , Knösel Friedrich , Edelmann Frank T. , Behrens Ulrich
Published: July 2007

Stabilization of Uranium(IV) Alkyls by Bulky Chelating Ligands: Molecular Structure of [PhC(NSiMe3)2]3UMe

Chelate ligand‐stabilized uranium σ‐methyl complexes are obtained in good yields by treatment of [RC6H4C‐(NSiMe3)2]3UCl (1) with methyllithium. The molecular structure of [PhC(NSiMe3)2]3UMe (3a) has been determined by X‐ray crystallography. A long uranium – carbon bond [249.8(5) pm] indicates steric crowding in the molecule. Analogously the dimethyluranium complex [(CF3)3C6H2C(NSiMe3)2]2UMe2 (4b) is prepared from [(CF3)3C6H2C(NSiMe3)2]2UCl2 and two equivalents of methyllithium. Reaction of 1 with NaBH4 yields the tetrahydroborates [RC6H4C(NSiMe3)2]3UBH4 (5). The strongly temperature‐dependent 1H‐NMR spectra of the complexes 1 and 3 have been studied in detail.
Spektroskopischer Nachweis eines Bis(amino)silylens
Authors: Veith M. , Werle E. , Lisowsky R. , Köppe R. , Schnöckel H.
Published: July 2007

Spectroscopic Identification of a Bis(amino)silylene

The photolysis of the silicon diazide 3a in benzene solution and in an Ar matrix is described. Both irradiations cause the elimination of 3 equivalents of N2. Loss of N2 from 3a in benzene leads to the formation of the analytically investigated product or products 4 of uncertain structure. However, the matrix photolysis of 3a results in a compound which is stable up to 77 K and has been identified as the bis(amino)silylene 2d by comparison of its IR spectra with those of the homologous Sn and Ge compond.
Wasserstoffübertragungen, 20[1a] Konkurrierende pericyclische Reaktionen von Dihydroarenen mit gespannten Cycloalkenen und ‐alkinen
Authors: Gerres Thomas , Heesing Albert
Published: July 2007

Hydrogen Transfer Reactions, 20[1a]. – Competitive Pericyclic Reactions of Dihydro Arenes with Strained Cycloalkenes and Cycloalkynes

While several highly strained cycloalkenes and cycloalkynes react with dihydroarenes to give products of Diels‐Alder or ene reactions only, 7 dehydrogenates two dihydroarenes as well. Semiempirical AM1 calculations on the transition structures for the [4 + 2] cycloadditions and the hydrogen transfer reactions show the independence of their geometry from the starting compounds. The preference for dehydrogenations by 7 is caused by both steric and solvent effects.
Benzoanellated centropolyquinanes, 11. Synthesis of tribenzotriquinacene and some centro‐substituted derivatives
Authors: Kuck Dietmar , Lindenthal Thomas , Schuster Andreas
Published: July 2007

The syntheses of tribenzotriquinacene (1a) and five centro‐substituted derivatives, 1b–1e and 1g, as well as of the related diindan 13 are reported. The three‐step synthetic sequences include the reduction of suitably substituted 2‐benz‐hydryl‐1,3‐indandiones 3 to the corresponding 1,3‐indandiols 4 and the twofold cyclodehydration of the latter to close two additional five‐membered rings at a time. Although the yields of the cyclodehydration step 4 · 1 are only low to moderate (10–33%), the overall approach allows the preparation of 5–50‐gram amounts of the centropolyindans in most cases by starting from simple 1,3‐indandiones 2a–2c. This includes the new synthesis of the parent tribenzotriquinacene (1a). The related Cs‐symmetrical diindan, 4b,9,9a,10‐tetrahydroindeno[1,2‐a]indene (13), has been prepared in high yield by using the same cyclodehydration technique. Scope and limitations of the double cyclodehydration strategy are described concerning the synthesis of 1,3‐indandiones with bulky substituents at C–2 and the cyclization of 1,3‐indandiols with an aptitude to undergo heterolytic cleavage of an exocyclic C–2–C‐α bond, in particular 4f. The course of the reduction of the 2,2‐disubstituted 1,3‐indandiones with lithium aluminum hydride is discussed on the basis of the stereochemistry of the product 1,3‐indandiols.
Mass‐spectrometric characterization of isomeric NNCCN and NCNCN Ions and neutrals
Authors: Muedas César A. , Sülzle Detlev , Schwarz Helmut
Published: July 2007

Neutralization‐reionization mass spectrometry as well as charge reversal and collisional activation experiments serve to distinguish and assign the connectivities NNCCN and NCNCN to isomeric pairs of anions, neutral radicals and cations of C2N3. Loss of N2 to generate C2N+ is the critical discriminant, and the assignment is further substantiated by subjecting these fragment ions to collisional activation experiments by using tandem‐mass spectrometry facilities.
CO2‐Aktivierung an Übergangsmetallzentren: Simulation enzymatischer CO2‐Fixierungs‐ und Transferreaktionen durch elektronenreiche (Diazadien)magnesium‐ und ‐mangan‐Komplexe
Authors: Walther Dirk , Ritter Uwe , Undeutsch Zzbernd , Kempe Rhett , Sieler Joachim
Published: July 2007

Activation of CO2 at Transition‐Metal Centres: Simulation of Enzymatic CO2 Fixation and Transfer Reactions by Electron‐Rich (Diazadiene)magnesium and ‐manganese Complexes

Electron‐rich diazadiene complexes of Mg and Mn can be used as model compounds for enzymatic carboxylation reactions e.g. the „dark reaction”︁ of the photosynthesis or in biotinedependent CO2 conversion reactions. The activity of the complexes to fix and transfer carbon dioxide strongly depends on the nature of the metal (Mg and Mn are active central atoms, other transition metals are inactive), the π aciditiy of the chelate ligand, and the structure of the complexes. The dimeric manganese complex IIa, the structure of which could be determined by X‐ray structure analysis, is one of the most active compounds. NMR studies reveal that the CO2 transfer to substrates with active C—H bonds takes place in the coordination sphere of the metal atom. Carrier of activated CO2 is the N—COO group.
Bis[bis(trimethylsilyl)methyl]galliumbromid und monomeres {Bis[bis(trimethylsilyl)methyl]gallium}[tris(trimethylsilyl)silyl]tellurid [(Me3Si)2CH]2Ga–TeSi(SiMe3)3
Authors: Uhl Werner , Layh Marcus , Becker Gerd , Klinkhammer Karl Wilhelm , Hildenbrand Thomas
Published: July 2007

Bis[bis(trimethylsilyl)methyl]gallium Bromide and Monomeric {Bis[bis(trimethylsilyl]methyl]gallium} [Tris(trimethylsilyl)silyl]telluride [(Me3Si)2CH]2Ga–TeSi(SiMe3)3

Bis[bis(trimethylsilyl)methyl]gallium bromide GaBr[CH(SiMe3)2]2 (4), prepared from Ga2Br4 · 2 dioxane and bis(trimethylsilyl)‐methyllithium in the molar ratio of 1:3, reacts with the sterically high‐shielded lithium tris(trimethylsilyl)silyltelluride · DME to yield [(Me3Si)2CH]2Ga–TeSi(SiMe3)3 (5). 5 can also be synthesized by a metathetic reaction between tetrakis‐[bis(trimethylsilyl)methyl]digallium(4) and bis[tris(trimethylsilyl)silyl]ditellane in toluene at 100°C. A crystal structure determination shows the compound to be monomeric in the solid state and the atoms of the central C2Ga–TeSi moiety to lie in the mirror plane of the molecule. The short Ga–Te distance of 253.5(1) pm as well as a hindered rotation (ΔErot ≈︁ 50 kJ · mol‐1) as detected by NMR measurements might be interpreted in terms of a π interaction between gallium and tellurium.
Polycyclische Verbindungen aus 2,5‐Norbornadien, Isopropylbenzol und Dehalogenierungs‐Produkten von Dihalogeno(diorganylamino)boranen. Reaktion von Bis(diisopropylamino)phenylboran mit Na/K‐Legierung und Difluor(diisopropylamino)boran
Authors: Maringgele Walter , Seebold Uwe , Meller Anton , Dielkus Sven , Pohl Ehmke , Herbst‐Irmer Regine , Sheldrick George M.
Published: July 2007

Polycyclic Compounds from 2,5‐Norbornadiene, Isopropylbenzene, and Dehalogenation Products of Dihalogeno(diorganylamino)boranes. Reaction of Bis(diisopropylamino)phenylborane with Na/K Alloy and Difluoro(diisopropylamino)borane

In the reaction of 2,5‐norbornadiene with Na/K alloy and dichloro(diisopropylamino)borane the species 1 was isolated, which contains six boron atoms in two triborolane rings. From isopropylbenzene and the dehalogenation products of (diisobutylamino)difluoroborane the ethenodiborolodiborol system 2 was isolated. When bis(diisopropylamino)phenylborane is treated with F2BN(i‐C3H7)2 and Na/K alloy the diborane(4) derivative 5 and 1,1,2,2‐tetrakisborylethane (6) are formed together with bis(diisopropylamino)fluoroborane (7). NMR (1, 11B, 13C, 19F) and MS data are given; for 1, 2, 5, and 6 the X‐ray structure analyses were performed.
Zink‐Komplexe von Tris(2‐pyridyl)phosphan und Tris(2‐pyridyl)arsan
Authors: Gregorzik Ralf , Wirbser Joachim , Vahrenkamp Heinrich
Published: July 2007

Zinc Complexes of Tris(2‐pyridyl)phosphane and Tris(2‐pyridyl)arsane

Reactions of zinc salts with the two title ligands are described which reveal several dissimilarities in their coordination behavior. From tris(2‐pyridyl)phosphane (1) and the zinc halides compounds with an L2Zn3 stoichiometry are isolated which, according to their Raman spectra, have the constitution [LZnHal]2[ZnHal4]. With tris(2‐pyridyl)arsane (2) the zinc halides form the 1:1 complexes LZnHal2. With Zn(SCN)2 and 1 only the L2Zn2+ species can be observed, while 2 produces the molecular complex LZn(SCN)2. Both 1 and 2 form a neutral 1:1 compound with Zn(NO3)2 which was shown for 1 · Zn(NO3)2 by an X‐ray structure analysis to consist in the solid state of octahedral complexes containing tridentate 1 and both monodentate and bidentate NO3‐. According to NMR spectroscopy this constitution seems to be maintained in solution. While the complexes 1 · ZnHal2 are insoluble, the complexes 2 · ZnHal2 and 2 · Zn(NO3)2 can be shown by NMR to undergo an equilibration in solution involving the LZn2+ and L2Zn2+ species of which only the LZn2+ species crystallizes as LZnX2. The zinc salts Zn(ClO4)2 and Zn(BF4)2 with noncoordinating anions react with 1 and 2 to form exclusively the L2Zn2+ complexes whose highly symmetrical octahedral geometry was ascertained for (1)2Zn(ClO4)2 by an X‐ray structure analysis.
Elektronenüberschuß‐Komplexe von Cobalt und Nickel mit Cyclobutadien‐Liganden: Synthese, Cyclovoltammetrie und Reaktivität
Authors: Herberich Gerhard E. , Klein Wolfram , Kölle Ulrich , Spiliotis Demetre
Published: July 2007

Electron‐Excess Complexes of Cobalt and Nickel with Cyclobutadiene Ligands: Syntheses, Cyclovoltammetry, and Reactivity[1]

A cyclovoltammetric investigation of tetraphenylcyclobutadiene complexes [ML(C4Ph4)]+ [1: ML = NiCp; 2a: ML = Co(C6H6); 2b: ML = Co(mesitylene)] reveals a reversible reduction to paramagnetic complexes 1 and 2a,b with a 19‐electron count, and a subsequent irreversible reduction to anions 1‐ and 2a,b‐ with a 20‐electron shell. Preparative reduction by one equivalent of CpFe(HMB) (HMB = C6Me6) produces the novel 19‐electron complexes 1 and 2b. Complex 1 can also be obtained by treatment of 1 · Br with one equivalent of CoCp2 at room temperature while reduction at ‐20°C with two equivalents of CoCp2 affords a novel C–C‐linked adduct CpNi[μ,η3:η4‐(C4Ph4–C5H5)]CoCp (5). Above ‐10°C a slow equilibrium between 5 and its components 1 and CoCp2 is observed with ΔH = 15 kJ/mol for the dissociation process. With an excess of the stronger reductant sodium amalgam the cations 1+ and 2a+ are reduced to give cyclobutenyl complexes ML(η3‐1,2,3,endo‐4‐C4HPh4) [6: ML = NiCp; 7: ML = Co(C6H6)]. 1 reacts with p‐nitrobenzyl bromide to give 1 Br and a p‐nitrobenzyl addition product CpNi[η3‐exo‐4‐(p‐O2NC6H4CH2)‐1,2,3,endo‐4‐C4Ph4] (11) while 2b reacts with MeI to give 2b · I and two isomeric methyl addition products (η5‐1,3,5,exo‐6‐C6H3Me4)Co(C4Ph4)] (12) and (mes)Co(η3‐exo‐4‐Me‐1,2,3,endo‐4‐C4Ph4) (13). Sodium‐amalgam reduction of the tetramethylcyclobutadiene cations [(arene)Co(C4Me4)]+ (4a: arene = C6H6; 4b: arene = mesitylene) affords diamagnetic dinuclear compounds of type 8–10 with C–C linkages between C4Me4/C4Me4, arene/C4Me4, and arene/arene rings, respectively.
Organotin cations stabilized by π coordination – synthesis and NMR studies in solution and in the solid state
Authors: Wrackmeyer Bernd , Kehr Gerald , Sebald Angelika , Kümmerlen Jörg
Published: July 2007

The organoboration of tetraalkynyltin compounds [Sn‐(CCR1)4 (1): R1 = Me (a), Et (b), Pr (c), iPr (d), tBu (e)] with triethylborane (2) proceeds stepwise. Intermediates with a cationic triorganotin (3, 5) and a dicationic diorganotin fragment (4), stabilized by intramolecular coordination of one and two alkynyl moieties, respectively, were isolated (3e, 4a) and/or identified by multinuclear NMR in solution (1H, 11B, 13C, 119Sn) and in the solid state (13C and 119Sn CP/MAS) (3e, 4a). The magnitude of 1J(13C13C) in 4a (101.0 Hz) is significantly smaller than that for sodium triethyl‐1‐propynylborate (7) (119.2 Hz), proving the weak coordination of the CC bond to the dicationic tin fragment. The final products of the organoboration, 1,4,6,9‐tetraalkyl‐2,7‐bis(diethylboryl)‐3,8‐diethyl‐5‐stannaspiro[4.4]nona‐1,3,6,8‐tetraenes (6b–6e) were obtained in high yield.
Koordinationschemie perhalogenierter Cyclopentadiene und Alkine, X[1] Darstellung und Molekülstruktur eines Cyclopentadienyl‐1,3‐dithiol‐π‐Komplexes, [C5Cl3(SH)2]Mn(CO)3
Authors: Sünkel Karlheinz , Blum Adrian
Published: July 2007

Coordination Chemistry of Perhalogenated Cyclopentadienes and Alkynes, X[1]. – Synthesis and Molecular Structure of a Cyclopentadienyl‐1,3‐dithiol π Complex, [C5Cl3(SH)2]Mn(CO)3

The reaction of [C5Cl4Li]Mn(CO)3 with elemental sulfur leads to [C5Cl4SLi]Mn(CO)3 (1), which is easily oxidized by air to the disulfide (OC)3Mn[C5Cl4S–SCl4C5]Mn(CO)3 (2). Addition of one equivalent of BuLi, followed by an excess of S8 produces the dithiolate [C5Cl3(SLi)2]Mn(CO)3 (3), which yields the dithiol [C5Cl3(SH)2]Mn(CO)3 (5) upon hydrolysis. The molecular structures of 2 and 5 have been determined by X‐ray diffraction.
Zur Darstellung von Nonafluorbutansulfonsäureestern
Authors: Frasch Markus , Sundermeyer Wolfgang , Waldi Joachim
Published: July 2007

Preparation of Esters of Nonafluorobutanesulfonic Acid

A series of new alkyl (2a–e), silyl (6a–1), germyl (7) and stannyl esters (8a, b) of nonafluorobutanesulfonic acid has been prepared by different methods (A–I) e.g. C4F9SO2OR [R = Me,Et, CH2CF3, CH2CCl3, CF3, GeMe3, SnMe3, SnEt3] and C4F9SO2OSiR3 [R = Me, Et, iPr, Bu, H, F, Cl, Ph, Ph2Me, PhMe2, Cl2Me]. These compounds are useful and extremely powerful alkylating or silylating reagents.
Diels‐Alder‐Reaktionen des Cyclobuta[1,2:3,4]dicycloheptatetraens, eines [4]Radialens
Authors: Hashmi Stephen , Szeimies Günter
Published: July 2007

Diels‐Alder Reactions of Cyclobuta[1,2:3,4]dicycloheptatetraene, a [4]Radialene

[4]Radialene 1 selectively adds active dienophiles like tetracyanoethylene, dimethyl acetylenedicarboxylate, 4‐phenyl‐1,2,4‐triazoline‐3,5‐dione, N‐phenylmaleimide, maleic anhydride, and benzyne at C‐1 and C‐10 to give Diels‐Alder adducts of type 6.
Polar Effects in Halogen Abstraction Reactions of Alkyl Radicals
Authors: Giese Bernd , Hartung Jens
Published: July 2007

In a series of structurally similar alkyl radicals 1a–c the tertiary 1,1‐dimethyl‐5‐hexenyl radical 1c reacts 30 times faster with carbon tetrachloride than the primary 5‐hexenyl radical 1a. The reactivity of the secondary 1‐methyl‐5‐hexenyl radical 1b aligns itself in between the primary and the tertiary radical 1a and 1c. The results indicate that the increasing nucleophilicity of the alkyl radicals is the major factor contributing to the reactivity.
Regiospezifische Insertion von Phenylacetylen in die ZrP‐Bindung von Cp2Zr{P(SiMe3)2}(Cl) und Folgereaktionen des Insertionsprodukts (Z)‐Cp2Zr{C(Ph)  C(H)P(SiMe3)2}(Cl)
Authors: Hey‐Hawkins Evamarie , Lindenberg Frank
Published: July 2007

Regiospecific Insertion of Phenylacetylene into the ZrP bond of Cp2Zr{P(SiMe3)2}(Cl) and Derivatives of the Insertion Product (Z)‐Cp2Zr{C(Ph)  C(H)P(SiMe3)2}(Cl)

The reaction of Cp2Zr{P(SiMe3)2}(Cl) (1) with phenylacetylene in boiling toluene yields regiospecifically the insertion product (Z)‐Cp2Zr{C(Ph)  C(H)P(SiMe3)2}(Cl) (2) which reacts with MeLi or nBuLi by forming the corresponding alkyl‐substituted zirconocene derivatives (Z)‐Cp2Zr{C(Ph)  C(H)P(SiMe3)2}(R) [R  Me (3), nBu (4)]. The attempt to prepare the C(Ph)  C(H)P(SiMe3)2− ligand directly from Li(THF)2P(SiMe3)2 and phenylacetylene yields HP(SiMe3)2 and LiCCPh. An X‐ray structure determination of 2 and 3 was carried out.
Makrobicyclische Endorezeptoren: Synthese, Kristallstruktur und Einschluß organischer Gastmoleküle
Authors: Lüer Ingo , Rissanen Kari , Vögtle Fritz
Published: July 2007

Macrobicyclic Endoreceptors: Synthesis, Crystal Structure, and Inclusion of Organic Guests

The macrobicyclic ligand 2 is synthesized in a one‐step cyclization procedure. According to an X‐ray structure analysis three dichloromethane guest molecules are included inside the cavity, whereas water and methanol are found outside the cavity. The rigid endo preorganization of the nitrogen donors allows the complexation of three 2,9‐disubstituted 1,10‐phenanthrolines inside the cavity.
Eine einfache Synthese von dimetallischen Zirconium/Aluminium‐Verbindungen mit planar‐tetrakoordiniertem Kohlenstoff
Authors: Erker Gerhard , Albrecht Markus , Werner Stefan , Nolte Matthias , Krüger Carl
Published: July 2007

A Simple Synthesis of Dimetallic Zirconium/Aluminium Compounds Containing Planar‐Tetracoordinate Carbon

(η2‐Alkyne)(trimethylphosphane)zirconium complexes [alkyne = cyclohexyne (3a) or diphenylacetylene (3b)] react with diisobutylaluminium hydride at room temperature by PMe3 cleavage and addition of HAl(isobutyl)2 to the in situ‐generated (η2‐alkyne)ZrCp2 intermediate to give the dimetallic Zr,Al compounds 4. These thermodynamically stable complexes contain a planar‐tetracoordinate carbon center whose uncommon coordination geometry is stabilized by a combination of the s̀‐donor interaction with both electropositive metals and the π‐conjugation of the ZrC  C moiety.
Studien zur C–H‐Aktivierung, VIII, Hydrido(vinyl)rhodium(III)‐Komplexe aus [RhCl(PiPr3)2] und Olefinen
Authors: Dirnberger Thomas , Werner Helmut
Published: July 2007

Studies on C–H Activation, VIII[1]. – Hydrido(vinyl)rhodium(III) Complexes from [RhCl(PiPr3)2] and Olefins

The reaction of [RhCl(PiPr3)2]n (1) with methyl vinyl ketone leads to the formation of the olefin complex trans‐[RhCl(CH2 = CHC(O)Me)(PiPr3)2] (2) which rearranges at ambient temperatures to give the hydrido(vinyl)rhodium(III) isomer magnified image (3). From 1 and the α,β‐unsaturated ketones RCH = CHC(O)Me (R = MeO, Me, Ph) the corresponding hydrido(vinyl) derivatives magnified imagemagnified image (5–7) are directly obtained. Treatment of 1 with acroleine CH2 = CHC(O)H gives the olefin complex trans‐[RhCl(CH2 = CHC(O)H)(PiPr3)2] (8) that does not react by C–H activation but by elimination of ethylene to form the carbonyl compound trans‐[RhCl(CO)(PiPr3)2] (4). The reactions of 1 with CH2 = CHCO2Me, (E)‐ and (Z)‐CH(CO2Me) = CH(CO2Me) afford monomeric (10, 12) or dimeric (14) olefin‐rhodium(I) compounds from which 12 is transformed by UV irradiation to give the hydrido(vinyl) isomer magnified imagemagnified image (16). Structurally related hydrido(vinyl)rhodium(III) complexes magnified imagemagnified image (17) and magnified image(PiPr3)2] (20, 21) are obtained either directly from 1 and the α,β‐unsaturated carbonyl compound or in two steps via the olefinrhodium(I) precursor. The IR and NMR data of the hydrido(vinyl) compounds prove unambiguously that the vinyl ligand is coordinated by the carbon and the carbonyl oxygen atom.
Hydride and Carbonyl Fluctionality in [HM10C(CO)24]‐ (M = Ru, Os)
Authors: Bailey Philip J. , Gade Lutz H. , Lewis Jack , Johnson Brian F. G.
Published: July 2007

The nature of the crystallographically isostructural hydrido‐cluster anions [HOs10C(CO)24]‐ (1) and [HRu10C(CO)24]‐ (2) in solution has been probed by variable‐temperature 13C‐NMR and two‐dimensional {1H}13C‐EXSY spectroscopy. The results of the study are interpreted in terms of both localised and global intramolecular exchange of the carbonyl and hydrido ligands which appear to occur by the same mechanisms in both clusters. The significance of the derived model for the understanding of the dynamic behaviour of more complicated systems such as [H4Os10(CO)24]2‐ (4) is discussed. The latter is at present the best molecular model for the structural aspects of synthesis gas adsorption at high density on metal surfaces.
(E,Z) Equilibria, 14. Substituent‐Induced Chemical Shifts along the C = N Bond of Schiff Bases
Authors: Knorr Rudolf , Ferchland Kathrin , Mehlstäubl Johann , Böhrer Petra , Hoang Thi Phung , Stephenson David S.
Published: July 2007

Sterically congested N‐(1,1,3,3‐tetraalkyl‐2‐indanylidene)‐amines 8–11, N‐(cyclopentylidene)anilines 13–17, and two of their salts are described, together with a short synthesis of 2‐imino‐1,1,3,3‐tetramethylindan (5). Some of these imines show rapid (E,Z) equilibration. Positively and negatively charged nitrogen functions (in 6 and 7) cause opposite 1H‐ and 13C‐NMR chemical shift effects along the C = N bond. Chemical shifts are almost equally affected by the lone electron pair and by the imino N–H bond. Substituent‐induced chemical shifts (SCS) have been assigned for all syn and anti positions with respect to methyl, phenyl, and 2,6‐dimethylphenyl groups at the imino nitrogen atom. The structurally well‐defined, rigid imines recommend themselves as new models for the calibration of theoretical approaches to syn/anti‐differentiating SCS.
Pyramidalization of the sp2‐Hybridized Carbon Atoms in 1,4‐Bridged 2,5‐Cyclohexadienes
Authors: Irngartinger Hermann , Oeser Thomas , Jahn Reiner , Kallfaß Dietmar
Published: July 2007

The 2,5‐cyclohexadiene‐2,3‐dicarbonitrile derivatives 1–7, the 1,4‐positions of which are linked by bridges with increasing lengths, have been prepared in order to determine the influence of the bridging on the structural parameters of this system. Therefore, we have examined the molecular structures of 1–7 by X‐ray analyses. Depending on the length of the bridge, the endo pyramidalization of the sp2‐hybridized carbon atoms established for 1 and 2 changes into exo orientation in the derivatives 5–7 to prevent eclipsed conformations between the substituents on the double bonds and on the bridgehead atoms. The intramolecular distances and folding angles of 2–7 vary systematically with the length of the bridges except the distance between the double bonds which is fixed to a magnitude of 2.42–2.45 Å. The syntheses of the compounds 1, 4, and 7 have not yet been reported in the literature.
Phosphanalkylene, 52. Umsetzung von [1‐(Trimethylsilyl)alkyliden]triphenylphosphoranen mit Kohlendioxid und Folgereaktionen
Authors: Bestmann Hans Jürgen , Dostalek Roman , Zimmermann Reiner
Published: July 2007

Phosphane Alkylenes, 52[1]. – Reactions of [1‐(Trimethylsilyl)alkylidene]triphenylphosphoranes with Carbon Dioxide

2‐(Triphenylphosphoranylidene) carboxylic acid esters 6 have been synthesized from 1‐(trimethylsilylalkylidene)phosphoranes 4 and carbon dioxide. The reactions of the ylides 6 with aldehydes 9 lead to α,β‐unsaturated silyl esters 10 in good yields and with high (E) stereoselectivity. Thermolysis of 6d affords (oxovinylidene)triphenylphosphorane (7).
Reaktionen von Komplexliganden, LI. Synthese und Reaktionen stabiler (Carben)tetracarbonyl‐Chelatkomplexe des Molybdäns
Authors: Dötz Karl Heinz , Larbig Harald , Harms Klaus
Published: July 2007

Reactions of Complex Ligands, LI[1]. – Synthesis and Reactions of Stable (Carbene)tetracarbonyl Chelate Complexes of Molybdenum

The stable (carbene‐C,O, ‐C,N, and ‐C,S)tetracarbonyl chelate complexes of molybdenum 2b–2c have been obtained by mild decarbonylation of their corresponding pentacarbonyl precursors 1b–1c. The chelate complexes have been characterized by elemental analyses and spectroscopic data. In addition, the structure of C,N chelate 2c has been confirmed by X‐ray analysis. In contrast to its C,N and C,S analogues, the C,O chelate complex 2a undergoes ring opening at temperatures as low as ‐40°C upon addition of triphenylphosphane. At 20°C the phosphane‐substituted chelate complex 4a is obtained. C,N and C,S chelate complexes require higher temperatures for the reaction to give similar fac‐tricarbonyl complexes 4b–4c.
Application of the Marcus Theory on the Reaction of Substituted Dibenzoyl Peroxides with Hydroquinones: Evidence for an Inner‐Sphere Electron Transfer (ET) Mechanism
Authors: Adam Waldemar , Schönberger André
Published: July 2007

The reaction of several substituted dibenzoyl peroxides 1 with methyl‐substituted hydroquinones 2 gives exclusively the corresponding benzoic acids 3 and quinones 4 as the two‐electron redox products. The spectrophotometrically determined rate constants of this reaction exhibit a small solvent effect, i.e. rate acceleration with increasing solvent polarity. Furthermore, it has been shown that the kinetics depend strongly on the substituents of the dibenzoyl peroxides as well as on the oneelectron oxidation potentials of the hydroquinones E0(HQ./H2Q). A Hammett plot gives ϱ = +1.8 ± 0.2 (r > 0.97), which indicates accumulation of negative charge on the dibenzoyl peroxide in the transition state. Good linear semilogarithmic plots of logk2 versus E0(HQ./H2Q) with slopes of 17 eV‐1 were observed for this redox process. A nonlinear statistical treatment of the kinetic data against the hydroquinone one‐electron oxidation potentials according to the Marcus theory affords a consistent set of one‐electron reduction potentials for the substituted dibenzoyl peroxides and the reorganization energies λ for the redox process. The E0(ROOR/RO.RO‐) values range between 150 mV for the 4‐NO2 to 47 mV for the 4‐MeO derivatives. A well‐fitting (r = 0.996) Hammett plot of E0(ROOR/RO.RO‐) versus s̀ values provides a slope of 100 mV per s̀ unit. The reorganization energy of ca. 17 ± 3 kcal mol‐1 speaks for an inner‐sphere electron transfer (ET).
NbTe4I und TaTe4I, zwei neue Tellurid‐Iodide mit Kettenstruktur
Authors: Tremel Wolfgang
Published: July 2007

NbTe4I and TaTe4I, Two New Telluride Iodides with Chain Structure

NbTe4I and TaTe4I, are synthesized in almost quantitative yields by reaction of the elements in the appropriate ratio at 540°C and 480°C, respectively. The crystal structure determinations show that both structures are built up from quasi one‐dimensional Nb(Te2)2 and Ta(Te2)2 chains that are separated by isolated iodine atoms. The metal–metal distances within these chains are outside the metal–metal bonding range. Both compounds are formally described as (Nb5+)(Te22−)2(I−) and (Ta5+)(Te2−2)2(I−), and semiconducting properties must be assumed. Short Te‐I contacts between Te atoms of and I atoms between the chains indicate significant anion‐cation charge transfer.
Synthesis and Structure of a New Bis[(trimethylphosphan)titanocene] Complex with a Bridging C2 Unit
Authors: Binger Paul , Müller Patrik , Philipps Petra , Gabor Barbara , Mynott Richard , Herrmann Albert T. , Langhauser Franz , Krüger Carl
Published: July 2007

Bis(trimethylphosphane)titanocene (1) reacts with 2‐methylene‐1,1‐diphenylcyclopropane (2) to give red crystalline (η2‐2‐methylene‐1,1‐diphenylcyclopropane)(trimethylphosphane)titanocene (3). In solution complex 3 degrades smoothly to form the new Cp2Ti(PMe3) – C2 – Ti(PMe3)Cp2 complex 4, the crystal structure of which has been elucidated by an X‐ray analysis.
Beiträge zur Chemie des Bors, 212. Azaphosphoniaborataborolidine und ihre Thermolyse zu Diazaphosphadiborinanen
Authors: Ederer Bernd , Ederle Henry , Nöth Heinrich
Published: July 2007

Contributions to the Chemistry of Boron, 212[1]. – Azaphosphoniaborataborolidines and their Thermolysis to Diazaphosphadiborinanes

Me3SiN = PN(SiMe3)2 (1) adds Lewis‐acidic diborylmethanes CH2[B(Cl)X]2 (6a–d, X = Cl, Me, Ph, Mes) to yield the five‐membered azaphosphoniaborataborolidines 9a–d by haloboration and formation of an intramolecular coordinative phosphorus boron bond. However, the less Lewis‐acidic diborylmethane CH2[B(Cl)NMe2]2 does not react with 1. NMR studies on 9 exhibit conformational dependence of the ring system on the bulkiness of X, suggesting a decreasingly folded structure for X = Mes > Ph > Me and a planar ring for X = Cl, the latter proven by an X‐ray structure analysis. 9 a, b rearrange their ring framework on heating with elimination of Me3SiCl to give diazaphosphadiborinanes 7. Compound 7b shows the typical reactions of a diamino(chloro)phosphane: oxidation by S8 yields the corresponding phosphane sulfide 17 while AlCl3 abstracts a chloride ion with formation of a phosphenium tetrachloroaluminate 13. In the reaction of 7b with BBr3 halogene exchange (to 16) dominates, while a phosphane borane adducts (15) is formed in a side reaction only.
Reaktive 3,4‐disubstituierte Derivate des 1,6‐Methano[10]annulens und ihr Synthesepotential
Authors: Neidlein Richard , Schröder Günter
Published: July 2007

Reactive 3,4‐Disubstituted Derivatives of 1,6‐Methano[10]annulene and their Synthetic Possibilities

Ethyl 4‐bromo‐1,6‐methano[10]annulene‐3‐carboxylate (4) is synthesized in three steps from cycloheptatriene‐1,6‐dicarbaldehyde 1. The key step of this conversion is a highly selective monoolefination of 1. The synthetic possibilities of 4 are discussed.
Flexible molecules with defined shape, II. Control of n‐heptane conformer populations by methyl substitution or ring annulation
Authors: Hoffmann Reinhard W. , Sander Thomas , Brumm Martin
Published: July 2007

The conformations of a flexible n‐heptane chain are considered. Six‐membered ring annulation at the inner bonds leads to 1,3‐disubstituted cyclohexanes, at the outer bonds to dicyclohexylmethane derivatives. Force‐field calculations show that these molecules maintain the conformational mobility of the heptane chain to a large degree, yet some populate one particular conformer to more than 80% (up to 99% in the case of 17). The predominant conformers of the molecules described here allow to represent each of the regular (diamond lattice type) conformations of a heptane chain. Moreover, for the open‐chain heptane derivatives the effect of methyl substitution on the conformational preferences has been examined. Finally, the adamantane derivative 32 has been identified in giving the heptane chain a 93% preference for the tg + g + t‐conformation.
Unsymmetrical phthalocyanines with a single macrocyclic substituent
Authors: Musluoglu Emel , Gürek Aysegül , Ahsen Vefa , Gül Ahmet , Bekaroǧlu özer
Published: July 2007

Unsymmetrical phthalocanines (5–7) with a single macrocyclic substituent are synthesized by the reaction of the boron complex of phthalonitrile (1) with the iminoisoindoline derivatives 2–4 of macrocyclic compounds, i.e. 15‐crown‐5, monoaza‐15‐crown‐5, and tetraazacyclotetradecane. The monomacrocycle‐substituted phthalocyanines are less soluble than the tetra‐substituted one.
Neue Perrhenate und Aminorheniumtrioxide mit Elementen der 14. und 15. Gruppe des Periodensystems
Authors: Wirringa Uwe , Roesky Herbert W. , Schmidt Hans‐Georg , Noltemeyer Mathias
Published: July 2007

New Perrhenates and Aminorhenium Trioxides with Elements of Group 14. and 15. of the Periodic System

New perrhenates have been prepared by reaction of Re2O7 with triphenylstibin oxide and di‐n‐butyltin oxide, respectively. The single‐crystal X‐ray structure of Ph3Sb(OReO3)2 (1) is reported. The reaction of Ph3SbO and nBu2SnO with Re2O7 in 1:2 molar ratio gives (O3ReOSbPh3)2O (2) and [O3ReOSn‐(nBu)2]2O (3), respectively. A trimethylstannyl‐substituted aminorhenium trioxide (Me3Sn)2NReO3 (4) has been prepared by reaction of Me3SiOReO3 and N(SnMe3)3.