bluuebunny/crossref_metadata_2025_split huggingface dataset:
Organische Synthesen mit Übergangsmetallkomplexen, 71. Methylcarben‐Komplexe von Chrom und Wolfram mit Cycloheptatrienyl‐, Cyclohexadienyl[Fe(CO)3]‐ und Cycloheptadienyl[Fe(CO)3]‐Resten als α‐Substituenten
Authors: Aumann Rudolf , Läge Mechtild , Krebs Bernt 
Published: July 2007

Organic Syntheses via Transition Metal Complexes, 71[1]. — Methylcarbene Complexes of Chromium and Tungsten with Cycloheptatrienyl‐, Cyclohexadienyl[Fe(CO)3]‐ and Cycloheptadienyl[Fe(CO)3] SubstituentsMethylcarbene complexes LnMC(OEt)CH3 1 [LnM = (CO)5Cr, (CO)5W] react with tropylium tetrafluoroborate (2a) or coordinated olefins of [C6H7Fe(CO)3]BF4 (2c), [C7H9Fe‐(CO)3]BF4 (2d), and [C7H7Fe2(CO)6]BF4 (2d) in the presence of Et3N to give complexes LnMC(OEt)CH2R 3a‐e and LnMC(OEt)CHR2 7a‐d by substitution of one or two α‐hydrogen atoms. The trimetallic WFe2 carbene complexes 7c, d derived from 1b with 2c, d form three stereoisomers each, which are fully characterized spectroscopically, (R*,R*,S*)‐7c additionally also by an X‐ray structure analysis, Ligand elimination from 3 and 7 may involve a‐and/or β‐hydrogen transfer reactions: Thus enol ethers (Z/E)‐6 are eliminated from α‐monosubstituted methylcarbene complexes 3a, c, d in yields of 62–90% by a pyridine‐induced transfer of an α‐hydrogen to the carbene carbon atom; with increasing steric demand of R the elimination of the (Z) isomer (Z)‐6 from 3 is favoured over the formation of the (E) isomer (E)‐6. The enol ether 10 becomes a minor side product in the pyridine‐induced ligand elimination from α‐disubstituted complexes 7a, b. In these cases the spirocyclopropane 8 is formed as the main product (60–82%) besides the 4,5‐homotropylidene 9 by a conformationally directed β‐hydrogen transfer reaction.
Deformierte chirale [n]Metacyclophane
Authors: Müller Bernd , Pischel Ivo , Nieger Martin , Vögtle Fritz 
Published: July 2007

Deformed Chiral [n]MetacyclophanesThe new dithiametacyclophane3cand the thiaazametacyclophanes6a, bare chiral, but do not contain chirality centres. They are obtained by cyclization of 1,3‐propanedithiol (2), or of the thiaza precursors5a, b, with the bis(bromomethyl) compounds1, 4a, b.The dynamic behaviour of the aliphatic chains in3c, and6a, b(flipping/rotation) have been studied by dynamic NMR. X‐ray analyses of3cand6adocument the out‐of‐plane deformation of the boat‐shaped benzene ring. The circular dichroism of enantiomer‐enriched3cis reported.
Kleine Ringe, 83. C3F2‐Isomere: Erzeugung durch gepulste Blitzpyrolyse und matrixspektroskopische Identifizierung
Authors: Maier Günther , Preiss Thomas , Reisenauer Hans Peter 
Published: July 2007

Small Rings, 83[1]. — C3F2 Isomers: Generation by Pulsed Flash Pyrolysis and Matrix‐Spectroscopic IdentificationMatrix‐isolated difluorovinylidenecarbene (4) has been generated by pulsed flash pyrolysis from 1‐chloro‐3,3‐difluoro‐cyclopropene (8a) and 3,3‐difluoro‐1,2‐diiodocyclopropene (8b). By subsequent photolysis 4 isomerizes to difluoropropargylene (5) and difluorocyclopropenylidene (6). The identification of the three new carbenes is based on the comparison of their experimental and calculated (MP2/6‐31G*) infrared spectra.
Dilithium‐N,N′‐bis(trimethylsilyl)hydrazid und ein Hydrolyseprodukt side‐on und end‐on an N2−2‐ und O2−2‐gebundene Li‐Kationen
Authors: Drost Christian , Jäger Carsten , Freitag Stefanie , Klingebiel Uwe , Noltemeyer Mathias , Sheldrick George M. 
Published: July 2007

Dilithium N,N′‐Bis(trimethylsilyl)hydrazide and a Hydrolysis Product: Side‐On‐ and End‐On‐Coordinated Li Cations to N2−2 and O2−2N,N′‐Bis(trimethylsilyl)hydrazine is converted into the dilithium derivative [(Me3Si)2N2Li2] · 2 thf (1) by nBuLi. Compound 1 forms a tetramer which lies on a crystallographic inversion centre. The Li+ ions are found to be end‐on to the NN units and also coordinated by thf, but three Li+ ions are also positioned symmetrically above the NN bonds. The hydrolysis of 1 in air leads to the formation of [(Me3SiOLi)4 · Li2O2 · LiN(SiMe3)2] · 2 thf (2) which contains four oxide and one peroxide ions. The O2−2 unit is side‐on‐coordinated by three Li+.
Chirale Lactole, XI. Eine Methode zur Bestimmung der Absolutkonfiguration chiraler Alkanole
Authors: Noe Christian R. , Knollmüller Max , Miculka Christian , Dungler Karin , Wagner Ernst , Ettmayer Peter 
Published: July 2007

Chiral Lactols, XI. ‐ A Method for the Determination of the Absolute Configuration of Chiral AlkanolsChiral secondary alcohols which are protected with the enantiomerically pure lactol 1 or 2 show significant differences in 13C‐chemical shifts around the glycosidic linkage. An easy method for determination of the absolute configuration of secondary alcohols based on this fact is described.
J‐Aggregate von 4‐Iod‐bis(dimethylamino)heptamethinium‐triiodid Synthese, Struktur und optische Eigenschaften
Authors: Dähne Lars , Grahn Walter , Tanaka Chizuko , Kawamoto Atsushi , Tanaka Jiro 
Published: July 2007

J‐Aggregates of 4‐Iodo‐bis(dimethylamino)heptamethine Triiodide. — Synthesis, Structure, and Optical PropertiesIodination of heptamethincyanine 2a gives the title compound 3. Its cations display all‐trans configuration in solution and in the crystalline state. In contrast to cations of 2a, those of 3 form one‐dimensional J aggregates, as proved by X‐ray analysis and optical reflection spectroscopy.
On the Reaction of 1‐Aza‐2‐azoniaallene Salts with Isocyanates
Authors: Wang Quanrui , Mohr Susanne , Jochims Johannes C. 
Published: July 2007

Abstract1‐Aza‐2‐azoniaallene salts 3, prepared in situ from geminal chloroalkylazo compounds 2 with Lewis acids, react with isocyanates 4 to give 4,5‐dihydro‐5‐oxo‐3H‐1,2,4‐triazolium salts 6 and 4,5‐dihydro‐5‐oxo‐1H‐1,2,4‐triazolium salts 7, respectively. The intramolecular cyclization of 3u opens a new route to cinnolinium salts 11. Allenes 3 react with isobutene to give pyrazolium salts 8. According to AM1 calculations the cycloadditions of 3 to isocyanates proceed in two steps via acylium salts 5 as intermediates. Mechanistically, the rearrangements 6 → 7 resemble Wagner‐Meerwein rearrangements rather than pericyclic [1,5]‐sigmatropic shifts.
Thermal Rearrangements, XXII. The Propargyl‐Cope Rearrangement of meso‐ and d,l‐3,4‐Dimethyl‐1,5‐hexadiyne‐3,4‐diol
Authors: Hopf Henning , Hamann Uwe , Zimmermann Gerhard , Remmler Matthias 
Published: July 2007

AbstractThe thermal behavior of meso‐ and d,1‐3,4‐dimethyl‐1,5‐hexadiyne‐3,4‐diol (meso‐ and d,1–4) has been studied at 400°C in the gas phase. In a tandem reaction the diols isomerize via the bisallenes 5 first to cis‐ and trans‐3,4‐diacetylcyclobutene (cis‐ and trans‐8) which have been detected as intermediates by 13C‐NMR spectroscopy as well as catalytic hydrogenation to 1,2‐diacetylcyclobutane (9). Subsequently, 8 stabilizes itself by ring opening to (E,Z)‐ and (E,E)‐3,5‐octa‐dien‐2,7‐dione (E,Z) and [(E,Z)‐6]. As a side reaction retroene cleavage of 4 to 2‐butynone (10) and methyl vinyl ketone (12) is observed. By pyrolysis of the pure diastereomers 4 it is shown that the retro‐ene process is more pronounced in the d,l than in the meso series.
Transition Metal Chemistry of Main Group Hydrazides, VI. New Directed Synthetic Strategies to Functionalized Heterocyclic Phosphorus(III) Hydrazides. First Examples of Crystal and Molecular Structures of [RPN(Me)N(H)]2 (R = Et, Ph, and tBu)
Authors: Sreenivasa Reddy V. , Katti Kattesh V. , Barnes Charles L. 
Published: July 2007

AbstractThe reactions of methylhydrazine with RPC12 (R = Et, tBu, and Ph) produced the cyclic phosphorus (III) hydrazides (1,2,4,5,3,6‐tetrazadiphosphorinanes) [RPN(Me)N(H)2 (R = Et, 1; (Ph, 2; tBu, 3) in good yields. The 1H‐and 31P‐NMR spectroscopic analysis indicated that 1 exists in chair and boat conformations. However, it crystallizes in the chair conformation exclusively. The X‐ray crystallographic investigation of all the three cyclo‐phosphorus hydrazides 1–3 confirms the existence of these compounds in the chair conformations in the solid state. The reaction of Mo(CO)4‐(NHC5H10)2 with 1 and 2 gives the dinuclear Mo(0) complexes [{Mo(CO)4(NHC5H10)}2(μ‐[RPN(Me)N(H)]2}] (R = Et, 5; Ph, 6). Based on 1H‐ and 31P‐NMR spectroscopic data, a bridging dinuclear dimetallic formulation is proposed for 5 and 6. The IR spectra indicate that the carbonyls are disposed in cis‐geometry around the Mo(0) center.
Komplexe mit makrocyclischen Liganden, II. Synthese, Struktur und elektrochemische Eigenschaften eines makrocyclischen Cu2IIMnII‐Komplexes vom Schiff‐Basen‐Typ
Authors: Brychcy Klaus , Jens Klaus‐J. , Tilset Mats , Behrens Ulrich 
Published: July 2007

Complexes with Macrocyclic Ligands, II. — Synthesis, Structure and Electrochemical Properties of a Macrocyclic CuMnII Complex of Schiff Base TypeA novel trinuclear Cu2Mn complex 4 of a macrocyclic Schiff base ligand obtained by condensation of 5‐tert‐butyl‐2‐hydroxy‐1,3‐benzenedicarbaldehyde with 1,2‐phenylenediamine was synthesized. The molecular structure of 4 was determined by X‐ray diffraction revealing a sandwich‐type structure as depicted by Figure 2. Electrochemical investigations (DCV measurements) showed two one‐electron reduction steps for the copper ions at E1/2 = ‐1.383 and ‐1.652 V (vs. Cp2Fe/Cp2Fe+).
Chemie polyfunktioneller Molekule, 112. Ringerweiterungsreaktionen an einem neuartigen spirocyclischen Cobaltaphosphazen mit Sauerstoff, Schwefel und Selen
Authors: Ellermann Jochen , Sutter Jörg , Knoch Falk A. , Moll Matthias 
Published: July 2007

Chemistry of Polyfunctional Molecules, 112. — Ring Enlargement Reactions of a Spirocyclic Cobaltaphosphazene with Oxygen, Sulfur, and SeleniumHerrn Prof. Dr. Ekkehard Lindner zum 60. Geburtstag gewidmet.
The spirocyclic cobaltaphosphazene 1 which contains cobaltconnected three‐, five‐, and six‐membered rings undergoes ring enlargement reactions by treatment with O2, S8, and Se8. The resulting paramagnetic spirocyclic cobalta‐phosphazenoids 2a–c (E = O, S, Se) consist of eight‐membered chelate rings connected at the spiro‐cobalt(II) centre forming a tetrahedral CoE4 core. The compounds 2a–c have been characterized by X‐ray analyses, 1H, 13C(1H), 31P(1H) NMR, IR, Raman, UV/Vis/NIR, EI/FD mass spectroscopy, and magnetic measurements.
Studien zur CH‐Aktivierung, X. Synthese von Alkyl(carbonyl)hydrido‐ und Allylhydrido‐Osmiumkomplexen durch Metall‐initiierte Fragmentierung von primären Alkoholen und Olefinen
Authors: Wecker Ulrich , Werner Helmut , Peters Karl , Schnering Hans‐Georg Von 
Published: July 2007

Studies on CH Activation, X. — Synthesis of Alkyl(carbonyl)hydrido‐ and Allylhydridoosmium Complexes by Metal‐initiated Fragmentation of Primary Alcohols and OlefinsHerrn Professor Dr. E. Lindner zum 60. Geburtstag gewidmet.
The reaction of [(Mes)OsCl2]n (1) with RCH2OH/NaOH in the presence of propene leads to complete fragmentation of the primary alcohol and formation of the alkyl(carbonyl)hydrido complexes [(Mes)OsH(R)(CO)] (2–7). The corresponding chloro derivatives [(Mes)OsC1(R)(CO)] (8–13) are obtained either by H/C1 exchange from 2–7 and CC14 or on treatment of [(Mes)OsR2(CO)] (16–21) with HC1 at ‐78°C. The carbonylosmium(II) compound [(Mes)Os(CO)C12] (15) reacts with iC4H9MgI to give a mixture of [(Mes)Os(iC4H9)2(CO)] (21), [(Mes)OsI(iC4H9)(CO)] (22), and [(Mes)Os(CO)I2] (23), whereas the reaction of 15 with C6H11CH2MgBr yields [(Mes)Os(CH2C6H11)2(CO)] (24), the olefin complex [(Mes)Os(CH2C6H10)(CO)] (25), and [(Mes)OsH(Br)(CO)] (26). The alkylhydridoosmium(II) compound [(Mes)OsH(CH2C6H11)(CO)] (28) is obtained from the chloro derivative 27 and Mg/Hg/C2H5OH. Treatment of 1 with iC3H7OH/NaOH and propene or isobutene affords the η3‐allylhydrido complexes [(Mes)OsH(η3‐2‐RC3H4)] (31, 32) in about 85% yield, while the reaction of 1 with iC3H7OH/NaOH and tert‐butylethene gives [(Mes)Os(CH2CHtC4H9)2] (35). The X‐ray structural analysis of [(Mes)OsH(η3‐2‐CH3C3H4)] (34), which like the corresponding η3‐allylchloro compound 33 is formed from the η3‐allylhydrido complex 31 or 32 and CC14, reveals a half sandwich‐type structure with an exo arrangement of the methallyl ligand.
Reaktive EC(p‐p)n‐Systeme, XXXVIII. Molekül‐ und Elektronenstruktur des 2‐(Diisopropylamino)‐1λ3‐phosphaethins iPr2NCP
Authors: Becker Gerd , Böhringer Matthias , Gleiter Rolf , Pfeifer Karl‐Heinz , Grobe Joseph , Van Duc Le , Hegemann Marianne 
Published: July 2007

Reactive EC(p‐p)π‐Systems, XXXVIII. — Molecular and Electronic Structure of 2‐(Diisopropylamino)‐1λ3‐phosphaethyne iPr2NCPThe molecular structure of 2‐(diisopropylamino)‐1λ3‐phosphaethyne iPr2NCP (3) has been investigated by X‐ray diffraction using a single crystal grown from the melt at −50.2°C. Bond distances and angles indicative for the electronic structure are: P°C 155.2(2), NC(sp) 131.2(3) pm, PCN 179.2(2)°; with a sum of angles 359‐8° the nitrogen atom has a trigonal‐planar coordination. The reported geometrical parameters of 3 have been reproduced by ab initio calculations (3‐21G and DZP basis), showing that the lengthening of the P°C and the shortening of the CN bond can be rationalized by the interaction of the π system of the triple bond with the 2p orbital at N. The He(I) photoelectron spectrum of 3 confirms the strong interaction.
Synthese und Struktur von 5,6,11,12‐Tetrakis(diisopropylamino)‐5,6,11,12‐tetra‐hydrodibenzo[c,g][1,2,5,6]tetraborocin
Authors: Krämer Albrecht , Pritzkow Hans , Siebert Walter 
Published: July 2007

Synthesis and Structure of 5,6,11,12‐tetrakis(diisopropylamino)‐5,6,11,12‐tetrahydrodibenzo[c,g][1,2,5,6]tetraborocineHerrn Prof. Dr. Gottfried Märkl zum 65. Geburtstag gewidmet.
Catalytic dimerization of 1,2‐bis(diisopropylamino)‐1,2‐dihydro‐1,2‐benzodiborete (1) with (phthalocyanine)palladium [Pd(pc)] leads to the eight‐membered title compound 2 in 95% yield. An X‐ray structure analysis of 2 exhibits a chair conformation for the central C4B4 ring (folding angle along B1B2/B1′B2′ 55.5°).
New Cyclopropyl Building Blocks for Organic Synthesis, 21. Diels‐Alder Reactions of Methyl 2‐Chloro‐2‐cyclopropylideneacetate with Electron‐Rich Dienes: Synthesis of Potential Intermediates for Illudin M
Authors: Primke Hartmut , Sarin Gurdeep S. , Kohlstruk Stephan , Adiwidjaja Gunadi , Meijere Armin De 
Published: July 2007

Abstract1‐Ethoxy‐ (8a) and 1‐(trimethylsilyloxy)‐1,3‐pentadiene (8b) cycloadded to 2‐chloro‐2‐cyclopropylideneacetate 6 to give low yields of endo/exo‐9a and ‐9b, respectively. On the other hand, furans 5a‐d added 6 (5b and 5d reacted regioselectively) to afford mixtures of the corresponding [4 + 2] cycloadducts endo‐11a‐d and exo‐11a‐d in good to high yields. 2‐Methyl‐5‐(trimethylsilyloxy)furan (5e) yielded a mixture of the four cycloadducts endo/exo‐11e and endo/exo‐12e, which upon attempted purification on silica gel underwent facile hydrolysis to give bicyclic hemiacetals endo/exo‐13 and 4‐hydroxycyclo‐2‐hexen‐1‐ones endo/exo‐14, respectively. Similarly endo/exo‐11f, and endo/exo‐12f, obtained from 2‐methoxy‐5‐methylfuran (5f) and 6, upon hydrolysis in the presence of silica gel gave endo/exo‐13 and endo/exo‐14 respectively. The structures of endo‐14 and exo‐12f were established by X‐ray crystallography. In the presence of florisil, the epoxides endo‐and exo‐16 were formed from trimethylsilyloxy‐substituted cycloadducts endo/exo‐11e. Selective reduction of the α‐chlorocarboxylate functionality in the cycloadducts endo‐11a‐d,f with LiBH4, followed by base‐catalyzed cyclization of the resulting chlorohydrins endo‐21a‐d, f yielded the corresponding epoxides endo‐22a‐d,f in 22–73% overall yield. Under identical conditions, the cycloadducts exo‐11a‐f could not be reduced to the corresponding chlorohydrins exo‐21a‐f. Regioselective reduction of the acetal epoxide endo‐22f to the tertiary alcohol endo‐23f was achieved with sodium dihydrobis(2‐methoxyethoxy)aluminate (Red‐Al®). On stirring with moist silica gel, the bicyclic acetals endo‐22d,f and endo‐23f cleanly hydrolysed to the highly substituted spiro[2.5]oct‐6‐en‐5‐ones endo‐24d,f (26 and 24% overall yields, respectively, in four steps from 5d,f and 6) and endo‐25f, respectively (23% overall yield in five steps from 5f and 6).
Liquid‐Crystalline D‐Glucose Dialkyl Acetals and Dodecyl D‐Glucofuranosides
Authors: Tietze Lutz F. , Böge Kai , Vill Volkmar 
Published: July 2007

AbstractTwo new systems of liquid crystalline glucose derivatives 5a‐d, 6a, b are prepared, studied and compared with reference compounds. The α‐ and β‐D‐dodecyl glucofuranosides 6a, b show smectic A phases. The clearing points of the furanosides are of the same magnitude as those of the pyranosides. The alkyl glucose acetals 5a‐d show columnar discotic phases. The clearing points are about 30°C lower than those of the corresponding thioacetals.
syn‐ar,ar′‐Difluorometacyclophanes: Strong 19F,19F Spin—Spin Interactions Transmitted through Space
Authors: Ernst Ludger , Ibrom Kerstin , Marat Kirk , Mitchell Reginald H. , Bodwell Graham J. , Bushnell Gordon W. 
Published: July 2007

AbstractThe close approach of the fluorine nuclei in the difluorinated syn‐[3.3]metacyclophanes 1, 2 and their [2.2] analogues 3, 4 leads to strong 19F,19F spin‐spin interactions which obey a through‐space mechanism. The geometries of 1–4 were estimated by MM2 molecular mechanics computations, those of 1 and 3 were also determined by X‐ray structural analyses. The decrease of the F,F internuclear distance in the series 1, 2, 3, 4 (2.78–2.48 Å) correlates with an increase of J(FF) from +42.1 to +99.2 Hz. It follows that, for a given distance d(FF), J(FF) is up to twice as large as a previous empirical correlation has assumed and even larger with respect to earlier theoretical calculations. Only weak F,F spin interaction occurs in 8, the anti isomer of 4.
Synthese von 6,6‐Dimethylfulven‐2‐carbonsäure‐methylester und ‐2,3‐dicarbonsäure‐dimethylester sowie deren Umsetzung zu 2,3,5,6‐substituierten Nordbornadienen
Authors: Herges Rainer , Reif Wolfgang 
Published: July 2007

Synthesis of Methyl 6,6‐Dimethylfulvene‐2‐carboxylate and Dimethyl 6,6‐Dimethylfulvene‐2,3‐dicarboxylate as well as their Reaction to 2,3,5,6‐Substituted NorbornadienesFulvenes 5 and 6 were synthesized by Diels‐Alder reaction of 6,6‐dimethylfulvene with methyl prop‐2‐ynoate and dimethyl but‐2‐ynedioate, catalytic reduction of the unsubstituted norbornadiene double bond, and a subsequent retro Diels‐Alder reaction under flash vacuum pyrolysis conditions, 5 and 6 are used as the diene component in synthesizing 2,5‐, 2,3,5‐, and 2,3,5,6‐substituted norbornadienes 7–9 by Diels‐Alder reaction with electron‐deficient alkynes.
Dibenzo[18]annulenes Incorporating Two Diphenylhexatriene Units
Authors: Michels Heinz‐Peter , Nieger Martin , Vögtle Fritz 
Published: July 2007

AbstractThe [6.6]cyclophanehexaene hydrocarbon 6a and the dimethoxy[6.6]cyclophanehexaene 6b are prepared starting with the unsaturated diacid 1. An X‐ray analysis of 6a exhibits a planar molecular skeleton. NMR and optical data prove a not fully conjugated macrocyclic π system and its division into two largely separate chromophores.
(5aS,10aS)‐Octahydro‐1H,5H‐dipyrrolo[1,2‐a:1′,2Prime;‐d]pyrazin «DPP» als Hilfsreagenz bei der enantioselektiven 1,2‐Addition von Grignard‐Reagenzien an prochirale Carbonylverbindungen
Authors: Zadel Guido , Breitmaier Eberhard 
Published: July 2007

(5aS,10aS)‐Octahydro‐1H,5H‐dipyrrolo[1,2‐a:1′,2′‐d]pyrazine «DPP» as Auxiliary Reagent for Enantioselective Alkylations of Prochiral Carbonyl CompoundsIn the presence of one equivalent of the title compound «DPP» (1) prochiral carbonyl compounds 2 react with Grignard reagents 3 in THF to form enantioselectively alcohols 4 with up to 98% ee, whereas the addition of one equivalent of triethylamine yields the opposite enantiomers with up to 97% ee. The optimal molar ratio of 1 and magnesium reagent 3 was determined by cryoscopic measurements. Asymmetric induction is supposed to arise from transition states involving monomeric octahedral complexes of Grignard reagent, chiral solvent, and carbonyl compound. DPP (1) also catalyses Grignard alkylations, because a tenth of its stochiometric amount gives an enantiomeric eccess four times more than as expected. Prepared from (S)‐proline, only the boat conformation of 1 induces the observed selectivity as detected by 13C‐NMR spectroscopy.
Wismutverbindungen mit voluminösen, mehrfach alkylierten Cyclopentadienyl‐Liganden
Authors: Sitzmann Helmut , Wolmershäuser Gotthelf 
Published: July 2007

Bismuth Compounds with Crowded Multiply Alkylated Cyclopentadienyl LigandsHerrn Professor Helmut Werner zum 60. Geburtstag gewidmet.
Bismuth complexes of alkylated cyclopentadienyl ligands are obtained in good yield on treating bismuth(III) halides with tetraisopropylcyclopentadienylsodium or 1,2,4‐tri‐tert‐butyl‐cyclopentadienyllithium. A 1:1 stoichiometric ratio gives the complexes [Cp4iBiCl2] (1), [Cp3tBiCl2] (2), and [Cp4iBiI2] (3) (Cp4i = C5iPr4H, Cp3t = C5H2tBu3‐1,2,4). According to X‐ray crystal structure analyses, 1 and 3 display dimeric structures with two bridging and two terminal halogeno ligands and η3‐coordination of the cyclopentadienyl rings. With half an equivalent of tetraisopropylcyclopentadienylsodium BiCl3 forms [Cp4iBi2Cl5] (4). An X‐ray crystal structure analysis of 3 reveals a central Bi2Cl10 core of two edge‐sharing BiCl6 octahedra coordinated to two Bi(η5‐Cp4i) fragments generating a framework of two face‐sharing cubes. Reaction of two equivalents of 1,2,4‐tri‐tert‐butylcyclopentadienyllithium with BiCl3 yields deep purple [Cp3t2BiCl] (5), a bent sandwich complex with an η3,η2‐bonding mode of the cyclopentadienyl ligands. Attempted formation of the octaisopropyl analogue of 5 from BiCl3 and two equivalents of tetraisopropylcyclo‐pentadienylsodium with elimination of propene gives [Cp4iCp3iBiCl] (6) (Cp3i = C5H2iPr3). Use of monodeuterated tetraisopropylcyclopentadienylsodium in the second substitution step gave pure [Cp4i([D1]Cp3i)BiCl] ([D1]6) proving the absence of ring exchange reactions under the reaction conditions employed and elimination of propene from the second incoming sterically crowded tetraisopropylcyclopentadienyl ring system. The importance of proper choice of solvent and reaction conditions on the formation of alkylated cyclopentadienyl bismuth derivatives is demonstrated by extensive formation of 1,1′,3,3′,5,5′‐hexa‐tert‐butyldihydrofulvalene (7) from 1,2,4‐tri‐tert‐butylcyclopentadienylsodium and BiCl3.
Übergangsmetallsubstituierte Acylphosphane und Phosphaalkene, XXI. Isophosphaalkine als μ3‐Liganden in Übergangsmetallkomplexen
Authors: Weber Lothar , Schumann Iris , Stammler Hans‐Georg , Neumann Beate 
Published: July 2007

Transition‐Metal‐Substituted Acylphosphanes and Phosphaalkenes, XXI. — Isophosphaalkynes as μ3‐Ligands in Transition Metal ComplexesReaction of the μ‐isophosphaalkyne complex (η5‐C5H5)2 (CO)2(μ‐CO)Fe2(μ‐CPMes) (Mes = 2,4,6‐Me3C6H2) (2a) with [(Z)‐Cyclooctene]Cr(CO)5 or Fe2(CO)9 gives rise to the μ3‐isophosphaalkyne complexes (η5‐C5H5)2(CO)2(μ‐CO)Fe2{μ‐CP[M(CO)n]Mes} 3a [M(CO)n = Cr(CO)5] and 4a [M(CO)n = Fe(CO)4]. Similarly (η5‐C5H5)2(CO)2(μ‐CO)Fe2{μ‐CP[Cr (CO)5]C6H2(CF3)3‐2,4,6} (3d) is obtained. The metal carbonyl fragments are attached to 2 in a η1‐fashion by the lone‐pair at the phosphorus. In contrast to this the treatment of 2a with (Ph3P)2Pt(η2‐C2H4) affords complex 5a in which 2a serves as an η3‐3e ligand towards the PtPPh3 moiety. The molecular structures of 3a and 5a are determined by single‐crystal X‐ray analysis.
Kumulierte Ylide, 22. Umsetzungen von (Triphenylphosphoranyliden)ethenon mit Halogenverbindungen und ihre präparative Anwendung
Authors: Bestmann Hans Jürgen , Geismann Christian , Zimmermann Reiner 
Published: July 2007

Cumulated Ylides, 22. — Reactions of (Triphenylphosphoranylidene)ethenone with Halogen Compounds and their Preparative Application(Triphenylphosphoranylidene)ethenone (6) reacts with halogen compounds 7 to yield four‐membered ylide phosphonium salts 9. Ring opening of 9 under different conditions gives rise to the formation of bis‐ylides 13, ylide salts 14, or bis‐phosphonium salts 15. Compounds 13/14 are hydrolysed to mono‐ylides 16, and the Wittig reaction with aldehydes yields unsaturated acylphosphoranes 17, which on thermolysis afford enyne carboxylic esters 18. From the bis‐salts 15 α‐branched divinyl ketones 22 are available by bis‐Wittig reaction.