bluuebunny/crossref_metadata_2025 huggingface dataset:
Reaktive EC(p–p)π‐Systeme, XXXII[1a] Phosphorylide Me3P = C(X)P(F)CF3 mit π‐Donor‐Substituenten X = F, OMe, OEt
Authors: Grobe Joseph , Van Due Le , Althoff Ulrike , Lange Gudrun
Published: July 2007

Reactive E = C(p–p)π Systems, XXXII[1]. – Phosphorus Ylides Me3P = C(X)P(F)CF3 with π‐Donor Substituents X = F, OMe, OEt

Fluorophosphaalkenes of the type F3CP = C(X)F react with tri‐methylphosphane in a 1:1 molar ratio at temperatures below – 20°C to give the novel phosphorus ylides Me3P = C(X)P(F)CF3 in good yields [X = F (4), 70%; OMe (7), 62%; OEt (8), 74%]. Compounds 4, 7 and 8 are stable up to about 10°C, but decompose at higher temperatures yielding in case of 4 Me3PF2 as main product. The 31P‐NMR spectra indicate a high barrier of rotation for the F3C(F)P group around the PIII–sp2C bond. The new ylides owe their existence to the electron withdrawing effect of the F3C(F)P unit which over‐compensates the destabilizing influence of the fluorine or alkoxy substituents on the sp2C atom.
Synthesis and X‐ray Structure of Binaphthyl‐Based Macrocyclic Diphosphanes and their Ni(II) and Pd(II) Complexes
Authors: Widhalm Michael , Kratky Christoph
Published: July 2007

16‐ and 18‐membered diphospha macrocycles (8, 12, and 15) have been synthesized from the corresponding 1,1′‐binaphthyl precursors (6, 11, and 14, resp.) and o‐phenylenebis(phenylphosphane) by means of high‐dilution conditions in 55, 49, and 87% yield. X‐ray structure analyses of 8a, 8b, 12b, and 12b · NiCl2 reveal their distinctly different conformations and conformational changes caused by complexation. These structural features are reflected in the pronounced different tendency of the compounds concerned to form Ni(II) and Pd(II) complexes.
1,8‐Bis(diphenylamino)‐ and 1,8‐Bis(methylphenylamino)naphthalene: Molecular Structure and Dynamic Behavior
Authors: Rimmler Gösta , Krieger Claus , Neugebauer Franz A.
Published: July 2007

The title compounds 2 and 3 have been synthesized from 1,8‐diaminonaphthalene. The molecular structure of 2 has been determined by X‐ray structure analysis and is discussed with regard to the arrangement of the peri‐diphenylamino substituents in the crystalline state and the steric strain in the molecule. NMR studies of 3 reveal two conformational processes. Their nature is discussed and barriers are reported.
Organophosphorverbindungen, 53[1] Cyclopropenyliden‐methylen‐diphosphane – neue gekreuzt konjugierte Phosphapolyene[2]
Authors: Breit Bernhard , Memmesheimer Holger , Boese Roland , Regitz Manfred
Published: July 2007

Organophosphorus Compounds, 53[1]. – Cyclopropenylidene‐methylene‐diphosphanes – New Cross‐Conjugated Phosphapolyenes[2]

The reaction of chloromethylenephosphanes 7 with the inverse cyclopropenylidenephosphanes 6, 10 leads to the formation of the title compounds 8 and 11 as a new class of cross‐conjugated phosphapolyenes. The structure of compound 8a has been confirmed by an X‐ray structural analysis.
Nichtkonzertierte Cope‐Umlagerung? 1,2,6,7‐Cyclodecatetraen‐Thermolyse
Authors: Roth Wolfgang R. , Schaffers Thomas , Heiber Margarita
Published: July 2007

Nonconcerted Cope‐Rearrangement? 1,2,6,7‐Cyclodecatetraene Thermolysis

From the pressure and oxygen dependence of the trapping rate a two‐step mechanism for the Cope rearrangement of the title compound is deduced, its energy profile established, and the heat of formation of the intermediate diradical 3 determined. In contrast to the meso compound the rearrangement of the rac isomer proceeds by two competing processes, a concerted and a nonconcerted pathway. The different behavior of the meso and rac compound can be correlated to the boat and chair geometry of the respective transition states.
Synthese, Strukturen und Eigenschaften von Cl2TeSeN2S und [Se2N2S]22+ [XSO3−]2 (X = F, CF3)
Authors: Haas Alois , Kasprowski Jörg , Pryka Michael
Published: July 2007

Synthesis, Structures, and Properties of Cl2TeSeN2S and [Se2N2S]22+ [XSO3−]2 (X = F, CF3)

Treatment of Se(NSO)2 with TeCl4 provides the colvalent five‐membered ring species (1). Reaction of Se(NSO)2 with XSO3H (X = F or CF3) leads to bis(1,3,4,2,5‐thiadiselenadiazolium) cations with the anions FSO3− (2a) and CF3SO3− (2b). X‐ray structure analyses for 1 and 2b are presented.
Reaktionen von Fluorphosphoranen mit (Trimethylsilyloxy)essigsäure(trimethylsilyl)ester: Synthese, NMR‐spektroskopische Studien und Röntgenstrukturuntersuchungen an mono‐ und spirocyclischen (Acyloxy)phosphoranen[1]
Authors: Well Michael , Albers Wilfried , Fischer Axel , Jones Peter G. , Schmutzler Reinhard
Published: July 2007

Reactions of Fluorophosphoranes with Trimethylsilyl (Trimethylsilyloxy)acetate: Structures, NMR‐Spectroscopic Studies and X‐ray Investigations of Mono‐ and Spirocyclic (Acyloxy)phosphoranes[1]

The reaction of the tetrafluorophosphoranes RPF4 (R = Me, Ph) with trimethylsilyl (trimethylsilyloxy)acetate (1) yields the corresponding monocyclic fluoro(acyloxy)phosphoranes 2 and 3 by cleavage of the Si—O bond and elimination of (CH3)3SiF. 2 and 3 were investigated by NMR spectrometry. The spirocyclic (acyloxy)phosphoranes 4–13 are formed analogously by the reaction of 1 with the fluorophosphoranes RPF4 [R = F, Me, Et, iPr, Me3SiCH2, CH2Cl, CHCl2, H2C = CH, C6H5, 2,5‐(CH3)2C6H3] in a molar ratio of 2:1. Spirophosphorane 14 is synthesized by the reaction of with PhN3 in the presence of a base. The trifluorophosphoranes R2PF3 (R = Me, Ph) react with 1 to form the monocyclic fluoro(acyloxy)phosphoranes 15 and 16, where the fluorine atom occupies an axial position at trigonal‐bipyramidal (TBP) phosphorus. X‐ray structure analyses of 4 and 7 reveal TBP geometry at phosphorus. The acyloxy ligand is found to form a chelate ring, whereby one axial and one equatorial site at TBP phosphorus are bridged.
Synthesis, Structure, and Reactivity of Chiral Rhenium Amido Complexes of the Formula (η5‐C5H5)Re(NO)(PPh3)(NRR')
Authors: Dewey Michael A. , Andrew Knight D. , Arif Atta , Gladysz J. A.
Published: July 2007

Reactions of primary and secondary amine complexes [(η5‐C5H5)Re(NO)(PPh3)(NHRR')]+ TfO− [2; R/R' = H/H (a), H/CH3 (b), H/C6H5 (d), CH3/CH3 (f), CH2CH2CH2CH2 (h)] with nBuLi give amido complexes (η5‐C5H5)Re(NO)(PPh3)(NRR') (1) in quantitative NMR yields. Although 1 d can be isolated in pure form, 1 f is converted upon workup into a dimeric bridging bis(amido) complex, cis‐[(η5‐C5H5)Re(NO){μ‐N(CH3)2}]2. The crystal structure of 1 d exhibits a pyramidal amido nitrogen atom. The diastereotopic methyl groups in 1 f readily exchange, as assayed by variable‐temperature NMR. Complexes 1 a, f react with TfOH to regenerate 2a, f, and with TfOR” to give the corresponding alkylated amine complexes. The basicities and nucleophilicities of the amido nitrogen atoms are shown to be greater than those of organic amines.
Bis(triisopropylphosphan)rhodiumdichlorid: Bildung und Struktur
Authors: Rappert Thomas , Wolf Justin , Schulz Michael , Werner Helmut
Published: July 2007

Bis(triisopropylphosphane)rhodium Dichloride: Formation and Structure

The mononuclear rhodium(II) complex trans‐[RhCl2(PiPr3)2] (4) has been obtained from [RhCl(PiPr3)2]n (3) and CCl4. The X‐ray structural analysis of 4 reveals a square‐planar coordination at the metal center. Reaction of 4 with H2 leads to the formation of the monohydrido compound [RhHCl2(PiPr3)2] (7) which on further treatment with H2 in the presence of Na[N(SiMe3)2] gives the dihydride [RhH2Cl(PiPr3)2] (8). Complex 7 has also been prepared from 3 and HCl.
Alkyleisen‐ und Alkylcobalt‐Reagenzien, V[1] Anticheleselektive Cyanoalkylierungen mit Cyanoalkyl‐Derivaten von Eisen(II), Titan(IV) und weiteren Übergangsmetallen
Authors: Kauffmann Thomas , Kieper Hansjörg
Published: July 2007

Alkyliron‐ and Alkylcobalt Reagents, V[1]. – Anticheleselective Cyanoalkylation with Cyanoalkyl Derivatives of Iron(II), Titanium(IV) and Further Transition Metals

In intermolecular competition experiments with substrate pairs which consist of a β‐functionalized ketone and a normal ketone, cyanoalkyl derivatives of Fe, Ti, Cr, and Mn prefer in every case the normal ketone (‚anticheleselectivity”). NC—CH2Ti(OiPr)3 (4a) and NC–CH2FeCl (3a) are the best reagents for the anticheleselective transfer of the cyanomethyl group. For the anticheleselective transfer of the cyaniosopropyl group, NC–CMe2FeCl (3b) is superior to the corresponding Ti reagents. The ability of 4a as a highly anticheleselective cyanomethylating reagent has also been demonstrated with an intramolecular competition system (diketone 13). The reasons for the observed anticheleselectivity are discussed.
Alkyleisen‐ und Alkylcobalt‐Reagenzien, VI[1] Hohe Überlegenheit der Reagenzien Me4CoLi2 und Me4FeLi2 im Vergleich zu Me2CuLi und Me4MnLi2 bei Kreuzkupplungen mit Vinylbromiden
Authors: Kauffmann Thomas , Stach Dirk
Published: July 2007

Alkyliron and Alkylcobalt Reagents, VI[1]. – High Superiority of Me4CoLi2 and Me4FeLi2 in Comparison to Me2CuLi and Me4MnLi2 in Cross Coupling Reactions with Vinyl Bromides

The complexes Me4MLi2 (M = Co, Fe, Mn) and Me2CuLi (prepared in situ, but well‐known in isolated form) were treated with a series of vinyl bromides. In nearly all cases Me4CoLi2 and Me4FeLi2 proved to be by far the best methylating reagents (high yields, reaction at – 78°C, short reaction time, no excess of the reagent necessary). These reagents will tolerate a hydroxy or cyano group in the substrate, whereas the classical reagent for methylation of vinylbromides, Me2CuLi, is strongly inhibited by these groups. With the methylation of hydroxyvinyl bromides a new method was found for the synthesis of allyl alcohols.
Nickelkomplexe eines 1,4‐Dihydro‐1,4‐Diboranaphthalin‐Derivates
Authors: Schulz Hartmut , Pritzkow Hans , Siebert Walter
Published: July 2007

Nickel Complexes of a 1,4‐Dihydro‐1,4‐diboranaphthalene Derivative*

2,3‐Diethyl‐1,4‐dihydro‐1,4‐dimethyl‐1,4‐diboranaphthalene (1) reacts with bis(1,5‐cyclooctadiene)nickel to form the complexes 2 and 3. The latter is also obtained from 1 and bis(allyl)nickel. However, the reaction of 1 with Ni(C3H5)2 in a 1:1 ratio leads to 4 containing the 1,5‐hexadiene ligand. The bis(allylnickel) triple‐decker 5 is obtained from the dianion 12‐ and [(C3H5)NiBr]2. In addition, the diamagnetic 44‐VE tetradecker 6 is formed in low yield. The constitutions of the complexes 2, 3, 4, and 6 are derived from spectroscopic data and are proven by X‐ray structure analyses.
Neutrale 30‐Valenzelektronen‐Tripeldeckerkomplexe mit cyclo‐E5‐Mitteldeck (E = P, As)
Authors: Rink Barbara , Scherer Otto J. , Heckmann Gert , Wolmershauser Gotthelf
Published: July 2007

Neutral 30 Valence‐Electron Tripledecker Complexes with cyclo‐E5 Middle Deck (E = P, As)[1]

In a stacking reaction of [(η5‐E5)M(η5‐C5Me5)] (3: E = P, As; M = Fe, Ru) with [M′(CO)3(NCMe)3] (4: M′ = Cr, Mo, W) at room temperature the neutral 30 valence‐electron tripledecker complexes [(η5‐C5Me5)M(μ‐η5:5‐E5) M′(CO)3] (5) are formed. Complexes 5b (M = Fe, E = P, M′ = Mo) and 5c, d (M = Fe, E = As, M′ = Cr, Mo) have been characterized by X‐ray structure analyses.
Phenylsilyl Chalcogenides, (Phenylsilyl)amines and Related Phosphonium (Phenylsilyl)methylides
Authors: Mitzel Norbert W. , Schier Annette , Beruda Holger , Schmidbaur Hubert
Published: July 2007

The synthesis of 1,3‐diphenyldisiloxane (1) by hydrolysis of chloro(phenyl)silane is optimized, 1,3‐diphenyldisilthiane (2) is made available by the reaction of H2S with PhH2SiCl and triethylamine. 1,3‐Diphenyldisilselenane (3) is prepared from K2Se and PhH2SiBr. Selective ammonolysis of PhH2SiBr leads either to bis(phenylsilyl)amine (4) or to tris(phenylsilyl)amine (5). (Phenylsilyl)bis(trimethylsilyl)amine (6) is prepared by the reaction of 1,1,1,3,3,3‐hexamethyldisilazane with chloro(phenyl)silane and triethylamine. According to a crystal structure determination the molecule of6features a planar Si3N skeleton. Phenylsilylated phosphonium methylides are available by two synthetic pathways: Transsilylation of phosphonium (trimethylsilyl)methylides and direct silylation of unsubstituted phosphonium methylides R3P = CH2. The structure of the molecule Me3P = C(SiH2Ph)2(11) in the crystal also exhibits a virtually planar PCSi2skeleton, isoelectronic with Si3N.
Enantioselektive Katalyse, VIII. Neue 1,2‐Bisphosphanliganden mit vier stereogenen Zentren und zusätzlichen Methoxygruppen für die asymmetrische katalytische Hydrierung
Authors: Nagel Ulrich , Bublewitz Alexander
Published: July 2007

Enantioselective Catalysis, VIII[1]. – New 1,2‐Bisphosphane Ligands with Four Stereogenic Centers and Additional Methoxy Groups for Asymmetric Catalytic Hydrogenation*

The synthesis of N‐acyl derivatives of all possible diastereomers of [P(R,S), 3R, 4R,P′(R,S)]‐3,4‐bis[(benzyl)phenylphosphanyl]‐pyrrolidine and [P(R,S), 3R, 4R,P′(R,S)]‐3,4‐bis[(2‐methoxybenzyl)phenylphosphanyl]pyrrolidine in optical pure form is described. Palladium and rhodium complexes with these ligands were prepared. The enantioselective hydrogenation of acetamidocinnamic acid with these rhodium complexes was studied at H2 pressures between 1 and 75 bar. There is only a small influence of the 2‐methoxy group in the ligand on the catalytic hydrogenation when compared with the respective unsubstituted diastereomer. The structure of {[PR,3R, 4R,P′R)‐1‐(tert‐butoxycarbonyl)‐3,4‐bis[(2‐methoxybenzyl)phenylphosphanyl]pyrrolidine‐P,P′}diiodopalladium was determined by X‐ray diffraction.
Isocyanid‐ und Heteroallen‐verbrückte Metallkomplexe, X. Protonierung und Alkylierung von (μ‐Acylisocyanid)‐ und (μ‐Iminoacylisocyanid)dieisen‐Komplexen
Authors: Schröder Andreas , Sperber Wilfried , Fuchs Joachim , Fehlhammer Wolf Peter
Published: July 2007

Isocyanide‐ and Heteroallene‐Bridged Metal Complexes, X[1,2]. – Protonation and Alkylation of (μ‐Acylisocyanide)‐ and (μ‐Iminoacylisocyanide)diiron Complexes

Protonation of the acyl isocyanide‐bridged diiron complexes cis‐[Fe2Cp2(CO)3(μ‐CNCOR)] [R = Ph (1a); C6H4NO2‐(4) (1b)] with HBF4 or HPF6 occurs at the isocyano nitrogen to give the cationic μ‐aminocarbyne complexes 2a and 2b, respectively. In contrast, the μ‐iminoacyl isocyanide complex 3 is both protonated and alkylated at the imino nitrogen. According to an X‐ray structure analysis of 4a, the resulting ligand systems in cis‐[Fe2Cp2(CO)3{μ‐Cmagnified imageNmagnified imageC(Ph)magnified imageN(Ph)R}]+BF4+ [R = H (4a); Et (4b)] are best described as hybrids of μ‐2‐azaallylidene‐and μ‐2‐azaallenylidene‐type resonance structures.
Synthese und Struktur von CpAlCl2‐Verbindungen mit sterisch anspruchsvollen Substituenten (Cp = Me5C5, EtMe4C5)
Authors: Koch Hans‐Joachim , Schulz Stefan , Roesky Herbert W. , Noltemeyer Mathias , Schmidt Hans‐Georg , Heine Andreas , Herbst‐Irmer Regine , Stalke Dietmar , Sheldrick George M.
Published: July 2007

Synthesis and Structure of CpAlCl2 Compounds with Sterically Demanding Substituents (Cp = Me5C5, EtMe4C5)[1]

The compounds Cp*AlCl2 (3) (Cp* = Me5C5) and Cp′AlCl2 (4) (Cp′ = EtMe4C5) have been prepared by the reaction of Cp*SiMe3 (1) and Cp′SiMe3 (2) with AlCl3. The single‐crystal X‐ray structures of 3 and 4 are reported.
Synthesis of the Novel μ‐(Phosphanoalkylidene) Complexes [Fe2Cp2(CO)2(μ‐CO){μ‐C(CN)PR2}] (PR2 = PEt2, PHCy, PHPh) and Molecular Structure of the PEt2 Derivative
Authors: Busetto Luigi , Carlucci Lucia , Zanotti Valerio , Albano Vincenzo G. , Monari Magda
Published: July 2007

Replacement of SMe2 at the pseudo‐alkylidyne μ‐carbon atom of [Fe2Cp2(CO)2(μ‐CO){μ‐C(CN)SMe2}]SO3CF3 by PR2H (PR2 = PEt2, PCyH, PPhH) results in the formation of the phosphonium salts [Fe2Cp2(CO)2(μ‐CO){μ‐C(CN)PHR2}]SO3CF3 which upon deprotonation with NEt3 yield the corresponding neutral complexes [Fe2Cp2(CO)2(μ‐CO){μ‐C(CN)PR2}]. These μ‐(phosphanoalkylidene) complexes have been characterized on the basis of IR, 31P{1H}‐, 1H‐, and 13C{1H}‐NMR spectra and by the X‐ray molecular structure of [Fe2Cp2(CO)2(μ‐CO){μ‐C(CN)PEt2}].
Synthesis of Stereoisomeric Ufolanes
Authors: Boldt Peter , Arensmann Eckart , Blenkle Martin , Kersten Helmut , Tendler Heike , Trog Rolf‐Stefan , Jones Peter G. , Döring Detlev
Published: July 2007

Three of the six possible stereoisomers of dodecahydroacenaphthylene, t,t,t‐ufolane (1), c,c,t‐ufolane (3), and c,c,c‐ufolane (5), have been synthesized for the first time. The configurations have been confirmed inter alia by an X‐ray analysis of the precursors 11, 14, and 23 and the bromine adduct 24 of c,c,c‐10‐ufolene (19), the precursor of 5.
Observations on Dibutylstannylene as Template for the Assembly of Macrocyclic Oligolactones
Authors: Bredenkamp Martin W. , Flowers Harold M. , Holzapfel Cedric W.
Published: July 2007

Dibutylstannylene‐mediated macrolactonization of methyl 4,6‐O‐benzylidene‐&7alpha;‐D‐glucopyranoside (2) with glutaryl and phthaloyl dichloride yields the respective dilactones 6e and 6f and parallel tetralactones 5e and 5f as well as the antiparallel tetralactone 4e in the case of glutarylation. The reaction with malonyl dichloride yields a negligible amount of the parallel tetralactone 5d and that of fumaryl and isophthaloyl dichloride yields polyesters only, a byproduct in all these reactions. The mechanism of stannylene‐medidted macrolactonization is discussed incorporating data pertaining to known hexa‐ and octalactone formation when succinyl dichloride is used. A correlation between stannylene dimer symmetry and tetralactone constitutional isomer selectivity is introduced.
Enantioselective Synthesis of Optically Active Pyridine Derivatives and C2‐Symmetric 2,2′‐Bipyridines
Authors: Bolm Carsten , Ewald Martina , Felder Marcel , Schlingloff Gunther
Published: July 2007

Optically active pyridine derivatives 2, 15, 18, 19, 21, 26, and 27 are obtained by enantioselective reduction of the corresponding ketones 5, 7, 11–13, 24, and 25 using the chiral borane reagent chlorodiisopinocampheylborane [(Ipc)2BCl]. Nickel(0)‐mediated coupling of bromopyridines 2, 15, and 31 gives C2‐symmetric 2,2′‐bipyridines (R,R)‐32, (R,R′)‐33, and (S,S)‐38, respectively, which form metal complexes with CoII, PdII, CuI, and AgI. Aryl‐substituted pyridines 26, and 39–41 are synthesized by palladium(0)‐catalyzed cross couplings of 2 and 15 with boronic acids 42–44.
The Molecular Structure of Triasterane: An Experimental and Theoretical Study
Authors: Ahlquist Bjørn , Almenningen Arne , Benterud Birgit , Trætteberg Marit , Bakken Pirkko , Lüttke Wolfgang
Published: July 2007

The molecular structure of triasterane (tetracyclo‐[3.3.1.02,3.02,6]nonane) has been investigated by using the gasphase electron‐diffraction method and by theoretical calculations. The experimental data are in accordance with the molecule having D3h symmetry. The C–C bonds in the three‐membered rings are observed to be slightly shorter than those in the methylene bridges [ra 1.508(5) versus 1.520(4) Å; 2s̀ in parentheses]. The C–C–C angle at the methylene bridges is observed to be 118.9(3)°, while the M–C–CH2 angle is determined to be 123.9(2)° (C–M is bisecting the cyclopropyl ring). Theoretical force‐field, semiempirical, and ab initio calculations of the triasterane molecule have also been carried out. The semiempirical results deviate substantially from the experimentally determined parameters, while the ab initio results, using a 6–31G* basis set, are in excellent agreement with the latter. The steric strain in triasterane has its origin mainly in nonbonded repulsion between the cyclopropyl groups and in torsion at the C–C bonds involving the methylene groups.
Cycloaddition Products from (1‐Diazo‐2‐oxoalkyl)silanes and Cyclopropenes. A Silatropic 2,3‐Diazabicyclo[3.1.0]hex‐3‐ene/1,4‐Dihydropyridazine Equilibrium
Authors: Munschauer Rainer , Maas Gerhard
Published: July 2007

(1‐Diazo‐2‐oxoalkyl)silanes 1a–h react with cyclopropene 4 to form 2‐silyl‐2,3‐diazabicyclo[3.1.0]hex‐3‐enes 5 and/or 1‐silyll‐1,4‐dihydropyridazines 6. In most cases, a temperature‐ and solvent‐dependent equilibrium 5 ⇄ 6 maintained by an N →N′ silyl shift exists in solution. With cyclopropene 10, only the 1‐silyl‐1,4‐dihydropyridazines 11 are obtained. None of the 1:1 adducts corresponds to the product expected from a [3 + 2] cycloaddition reaction between the components. Evidence is presented that 1‐diazo‐2‐siloxy‐1‐alkenes 2 are initially formed from 1 by a 1,3‐(C → O) silyl shift and are then trapped by the cyclopropene in a 1,3‐dipolar cycloaddition reaction.
(Tetracyannaphthalocyaninato)eisen(II) mit Isocyaniden als axialen Liganden
Authors: Hanack Michael , Großhans Ronald
Published: July 2007

(Tetracyanonaphthalocyaninato)iron(II) with Isocyanides as Axial Ligands

(Tetracyanonaphthalocyaninato)iron(II) [(CN)4‐2,3‐NcFe; 6] is obtained by treating 2,3,6‐tricyanonaphthalene (5) with iron(II) acetate. Compound 5 is synthesized according to the route given in Scheme 1. The mononuclear bisaxial isocyanide complexes (CN)4‐2,3‐NcFeL2 7–9 with L = tBuNC, cHxNC and AdNC as well as the bridged complex [(CN)4‐2,3‐NcFe(dib)]n (10) are formed as stable compounds by treating 6 with the neat ligands L. The spectroscopic properties of the complexes are described and compared with the analogous compounds (CN)4PcFeL2, 2,3‐NcFeL2, 1,2‐NcFeL2, and with PcFeL2. The bridged complex [(CN)4‐2,3‐NcFe(dib)]n (10) exhibits only poor semiconducting properties as compared to [2,3‐NcFe(dib)]n. The oligomer 10 can be doped with iodine, and the resulting product [(CN)4‐2,3‐NcFe(dib)I1.4]n shows a powder conductivity s̀RT = 2 × 10‐5 S/cm at room temperature.
Herstellung und Umsetzungen von (R,R)‐ und (S,S)‐3‐Trifluormethyloxiran‐2‐carbonsäure‐ethylester, einem vielseitigen, leicht zugänglichen CF3‐haltigen Synthesebaustein
Authors: Bussche‐Hünnefeld Christoph Von Dem , Seebach Dieter
Published: July 2007

Preparation and Reactions of Ethyl (R,R)‐ and (S,S)‐3‐Trifluoromethyloxirane‐2‐carboxylate, a Versatile, Easily Accessible CF3‐Containing Building Block for Synthesis

A facile three‐step route has been elaborated leading from 4,4,4‐trifluoro‐3‐oxobutanoate to the trifluoro glycidic ester 1 mentioned in the title (0.1‐mole scale). Reactions with azide (→ 4, 5) and with organometallic compounds such as cuprates (→ 3, 6), lithium (→ 7, 8), and magnesium derivatives (→ 9–11) furnish novel enantiomerically pure trifluoromethyl‐substituted carboxylic esters, ketones, diols, and epoxy alcohols. The latter ones undergo selective isomerizations by Payne rearrangement (11 → 12) in aqueous NaOH/acetone or tert‐butyl alcohol.
Ketonpyrolyse: Darstellung und Röntgen‐Kristallstruktur eines Oxa[3.2.1]cyclophans
Authors: Breitenbach Jörg , Ott Frank , Vögtle Fritz , Nieger Martin
Published: July 2007

Ketone Pyrolysis: Preparation and X‐ray Structure Analysis of an Oxa[3.2.1]cyclophane

The oxa[3.2.1]cyclophane 2 was obtained for the first time in the course of the thermal extrusion of carbon monoxide from the dimethoxy[3.3]metacyclophanedione 1. The X‐ray structure analyses of 1 and 2 are reported. 1 shows a syn‐type conformation.
2‐Oxabicyclo[3.2.1]oct‐7‐yl‐Kationen
Authors: Kirmse Wolfgang , Mönch Dietmar
Published: July 2007

2‐Oxabicyclo[3.2.1]oct‐7‐yl Cations

2‐Oxabicyclo[3.2.1]octan‐7‐one (10) was prepared in five steps, starting from 3‐cyclopenten‐1‐ol (5). The tosylhydrazone 11, derived from 10, was photolyzed in 0.5 N NaOD/D2O to give >99% of 2‐oxabicyclo[3.2.1]octan‐exo‐7‐ol (9) with equal distribution of D at C‐1 and C‐7. In contrast to the parent 6‐bicyclo[3.2.1]octyl cation (1), the oxa analog 14 exhibits the same symmetry as was observed with the 6‐oxa‐2‐norbornyl cation (13). The conformational effects that are evident in 1 are overruled by strong n participation.
Umlagerungen von Tricyclo[3.2.1.12,4]non‐6‐yl‐, Tricyclo[4.2.1.12,5]dec‐3‐yl‐ und Tricyclo[4.2.2.12,5]undec‐3‐yl‐Kationen
Authors: Kirmse Wolfgang , Mönch Dietmar , Müller Katja , Gomann Klaus
Published: July 2007

Rearrangements of Tricyclo[3.2.1.12,4]non‐6‐yl, Tricyclo[4.2.1.12,5]dec‐3‐yl, and Tricyclo[4.2.2.12,5]undec‐3‐yl Cations

The tricyclic ketones 5, 9, 13, and 24 were prepared by modified or novel routes. The corresponding tosylhydrazones 10, 11, 14, and 25 were photolyzed in 0.5 N NaOH (NaOD) to generate the title cations 2, 15–17, and 28, respectively, by way of diazonium precursors. The distribution of deuterium labels revealed rapid degenerate Wagner‐Meerwein rearrangements of 2 and 28 contrasting the unsymmetrical behavior of the parent bicyclo[3.2.1]oct‐6‐yl cation (1). The virtually irreversible rearrangement of 17 to 15, on the other hand, mirrors the preferred chair conformation of 1. The results with tricyclic carbocations support our previous explanation for the exceptional reactivity of 1.
Investigation of the Enantiomerization Barrier of Homofuran by Computer Simulation of Interconversion Profiles Obtained by Complexation Gas Chromatography
Authors: Schurig Volker , Jung Martin , Schleimer Michael , Klärner Frank‐Gerritt
Published: July 2007

By computer simulation of experimental interconversion profiles, obtained by complexation gas chromatography, rate constants of enantiomerization have been determined for homofuran between 95 and 130°C. Since enantiomerization proceeds at similar rates in the mobile and stationary phase, the rate constants obtained by an Arrhenius plot are in excellent agreement with values determined independently by polarimetry between 60 and 90°C. We thus demonstrate that dynamic chromatography can be an easy means for the rapid determination of enantiomerization (or isomerization) barriers of ca. 70–120 kJ mol‐1 requiring only minute amounts of racemic sample.
Darstellung und Reaktivität von {(η5‐C5H4SiMe3)2Ti(CCPh)2}Ni(CO)
Authors: Lang Heinrich , Imhof Wolfgang
Published: July 2007

Synthesis and Reactivity of {(η5‐C5H4SiMe3)2Ti(CCPh)2}Ni(CO)

The synthesis and reactivity of {(η5‐C5H4SiMe3)2Ti(CCPh)2}Ni(CO) (6) is described. (η5‐C5H4SiMe3)2Ti(CCPh)2 (1a) reacts with equimolar amounts of Ni(CO)4 (5) to afford the dinuclear complex {(η5‐C5H4SiMe3)2Ti(CCPh)2}Ni(CO) (6) in 95% yield. In 6 both phenylethynyl units are η2‐side‐on‐coordinated to the Ni(CO) moiety. When 6 is treated with HX or X2 (X = Cl, Br) the Ti–C(alkynyl) σ bond is cleaved, and the corresponding titanocene dihalides (η5‐C5H4SiMe3)2TiX2 (7) are formed. With PRR′2 [8a: R = R′ = OMe; 8b: R = C = CPh, R′ = Ph; 8c: R = Ph, R′ = CCPh] 6 reacts by substitution of the nickel‐bonded carbonyl ligand to form {(η5‐C5H4SiMe3)2Ti(CCPh2}Ni(PRR'2) (9). The reactivity of 9b, which contains a noncoordinated phenylethynyl unit, has been investigated by using Co2(CO)8 (10) and Fe2‐(CO)9 (13). With 10 the compounds {η5‐C5H4SiMe3)2Ti(CCPh)2}Ni(CO) (6), [μ‐(η2‐Ph2PCCPh)]Co2(CO)6 (11) and {[μ‐(η2‐Ph2PCCPh)]Co2(CO)5}2 (12) can be obtained. Complex 11 yields upon heating by decarbonylation and dimerization the six‐membered cyclic compound 12. Whereas, the reaction of 9b with 13 affords {(η5‐C5H4SiMe3)2Ti(CCPh)2}Ni(CO) (6) next to the dinuclear complex Fe2(CO)6‐(μ‐PPh2)[μ‐(η1:η2‐CCPh)] (14).
Hexasilylbenzene, C6(SiH3)6
Authors: Rüdinger Christoph , Beruda Holger , Schmidbaur Hubert
Published: July 2007

The title compound was obtained in a four‐step synthesis starting from (4‐methoxyphenyl)silane. Owing to the presence of activating p‐methoxy groups in the key intermediate hexakis[(4‐methoxyphenyl)silyl]benzene (4), the peripheral aryl groups can be cleaved selectively from the silicon atoms with trifluoromethanesulfonic acid, leaving the Si–C bonds to the central benzene ring intact. LiAlH4 reduction of the resulting hexakis[(trifluoromethylsulfonyloxy)silyl]benzene (5) finally leads to crystalline, sublimable, air‐stable C6(SiH3)6 (6), m.p. 165°C. In the crystals (triclinic, space group P&1macr;) the structure of the centrosymmetrical molecules approaches very closely point group D3d, as predicted from theoretical considerations.
Wasserstoffübertragungen, 21[1] Pericyclische Wasserstoff‐Übertragung von 1,2‐Dihydroarenen auf ein Cycloheptin
Authors: Gerres Thomas , Heesing Albert
Published: July 2007

Hydrogen Transfer Reactions, 21. – On the Pericyclic Hydrogen Transfer from 1,2‐Dihydroarenes to a Cycloheptyne

The aromatization of 1,2‐dihydroarenes by thiacycloheptyne 1 takes place by a pericyclic process. This mechanism is supported by the dependence of the reactivity on the π system, absence of both substituent and solvent effects, a strong negative entropy of activation, high stereoselectivity of hydrogen abstraction, as well as size and consistency of primary isotope effects and semiempirical calculations of the transition state.
Synthesis of new soluble triphenodithiazines and investigation of their donor properties
Authors: Kistenmacher Axel , Adam Martin , Baumgarten Martin , Pawlik Jürgen , Räder Hans‐Joachim , Müllen Klaus
Published: July 2007

The syntheses of 6 and 7, starting from 3,6‐dichloro‐2,5‐bis(2‐thioanisido)‐1,4‐benzoquinone (4), are reported. The solid‐state conformations of 6 and 7 are elucidated by X‐ray structure analysis, and the cyclovoltammetric investigation of 6 and 7 in solution shows low and reversible oxidation half‐waves for both compounds. The relatively high oxidation potentials of 7 compared to 6 are related to their conformational features. EPR measurements on the radical cations derived from 6 and 7 both suggest a planarized conformation of these species. Oxidation of 6 with strong oxidants leads quantitatively to the quinoid triphenodithiazine 8, whereas the charge‐transfer complex formed between 7 and DDQ exhibits semiconducting properties.
Inter‐ and intramolecular hetero diels‐alder reactions, 39. Influence of phenylthio and alkylthio substituents on the reactivity of 1‐Oxa‐1,3‐butadienes in hetero diels‐alder reactions
Authors: Tietze Lutz F. , Fennen Jens , Wichmann Jürgen
Published: July 2007

The synthesis of the cyclic enamino ketones 1–3 bearing an alkylthio or an phenylthio group and their reactivity in hetero Diels‐Alder reactions with enol ethers is described. Only compound 3 with an phenylthio group undergoes a cycloaddition with 16a–d to afford the diastereomeric adducts 17a–d and 18a–d. To estimate the activation by a phenylthio and alkylthio group semiempirical PM3/RHF calculations of the frontier orbital energies and coefficients of different enamine carbaldehydes have been performed.
Alkylierung von Chinonen mit O‐silylierten Ketenacetalen in LiClO4/Ether als Reaktionsmedium
Authors: Ipaktschi Junes , Heydari Akbar
Published: July 2007

Alkylation of Quinones by O‐Silylated Ketene Acetals in LiClO4/Ether as Reaction Medium

O‐Silylated ketene acetals (2, 5) undergo 1,4‐conjugative addition to α,β‐unsaturated carbonyl systems of quinones 1 in the presence of lithium perchlorate in ether to form 2(3H)‐benzofuranones 3
Trimethylsilylcyanid als Umpolungsreagenz, XIX[1] Dreikomponentenreaktionen zur Synthese von ungesättigten γ‐Ketoestern
Authors: Hünig Siegfried , Koch Michael
Published: July 2007

Trimethylsilyl Cyanide – A Reagent for Umpolung, XIX[1]. – Unsaturated γ‐Keto Esters by Three‐Component Reactions

Addition products 1a–c of α,β‐unsaturated aldehydes and trimethylsilyl cyanide are deprotonated and added to methyl acrylate (2). On alkylation with the allylic bromo dienes 3a, b the intermediate ester enolates yield the final adducts 4aa–4cb (83–95%). Deprotection transforms these adducts into 5aa‐5cb (72–98%), which contain the functionalities of an α,β‐unsaturated ketone, a carboxylic ester group, and a diene in the appropriate arrangement for intramolecular Diels‐Alder reactions. Yields between 64 and 79% of 5 are achieved if the reaction sequence 1 + 2 + 3 → 4 → 5 is performed without isolation of 4.
C,C‐Verknüpfungen mit Schwefel‐stabilisierten Carbanionen, 2[1] Reaktionen des 2‐(Methylthio)thiolan‐Carbanions mit Elektrophilen[2]
Authors: Böge Askan , Brunck Jörg‐Stephan , Schwär Gerhard , Voß Jürgen
Published: July 2007

C,C Coupling with Sulfur‐Stabilized Carbanions, 2[1]. – Reactions of the 2‐(Methylthio)thiolane Carbanion with Electrophiles[2]

The „semicyclic” thioacetal 2‐(methylthio)thiolane (4) is easily prepared from thiolane (tetrahydrothiophene). It is readily deprotonated by butyllithium to give the lithium derivative 5, which reacts with alkyl halides, saturated and α,β‐unsaturated carbonyl compounds, and benzonitrile to form the alkyl derivatives 6, carbinols 7, allyl alcohols 8, and – after hydrolysis – the ketone 9. The diastereoselectivity of the C,C coupling reaction is discussed.
trans‐1‐(Dimethylamino)‐1,3‐butadiene – Concerted and Stepwise (4 + 2) Cycloadditions
Authors: Sustmann Reiner , Rogge Monika , Nüchter Ursula , Bandmann Heinz
Published: July 2007

trans‐1‐(Dimethylamino)‐1,3‐butadiene is allowed to react with methyl acrylate, acrylonitrile, maleo‐ and fumaronitrile, dimethyl maleate and fumarate, as well as with dimethyl dicyanomaleate and dicyanofumarate. In all cases except the two last ones where only a single isomer is obtained mixtures (endo/exo) of cycloadducts are formed. Structures are determined by a combination of one‐ and two‐dimensional NMR spectroscopy. The E/Z isomeric maleo‐ and fumaronitrile add stereospecifically to the diene. Cycloaddition of dimethyl maleate and fumarate leads to the same mixture of isomers in almost the same ratio. The reaction of dimethyl dicyanomaleate and dimethyl dicyanofumarate yields a cycloadduct which seems to be the thermodynamically most stable one. The results are interpreted in such a manner that a concerted cycloaddition takes place with maleo‐ and fumaronitrile, while stepwise reactions, presumably proceeding via zwitterions, are observed with dimethyl maleate, fumarate, the strongly electrophilic dimethyl dicyanomaleate and dicyanofumarate. With increasing capability of the dienophile to stabilize a negative charge the mechanism changes from a concerted to a stepwise reaction.
Reactions of 1,1‐bis(dimethylamino)‐1,3‐butadiene with olefins – (4 + 2) cycloadditions and zwitterion formation
Authors: Sustman Reiner , Rogge Monika , Nüchter Ursula , Bandmann Heinz
Published: July 2007

1,1‐Bis(dimethylamino)‐1,3‐butadiene (1) as a strong donor diene (E1/2 = 0.03 V vs. SCE, 1st IPv = 6.94 eV) is treated with acrylonitrile, dimethyl dicyanofumarate, and tetracyanoethylene. Cycloaddition with acrylonitrile is slow and requires elevated temperatures at which elimination of dimethylamine with formation of 1‐cyano‐2‐(dimethylamino)‐1,3‐cyclohexadiene occurs. The reaction of 1 with TCNE at −40°C in acetonitrile is very fast and leads to the zwitterion 5. At T ⩾ −20°C, 5 eliminates hydrogen cyanide to give a highly colored (λmax = 489 nm, lgϵ = 4.716) merocyanine. A zwitterion 9 generated from 1 and dimethyl dicyanofumarate can be isolated in crystalline form. The structural analysis shows that the zwitterions are produced by attack of the olefin at the antiperiplanar conformation of 1. Both zwitterions which can be trapped as crystalline picrates cannot be converted to cycloadducts. These results suggest that cycloaddition is observed if zwitterion formation becomes energetically unfavorable.
The Pagodane Route to Dodecahedranes Scope and Limitation of the Dehydrocyclization Stratagem
Authors: Lutz Georg , Pinkos Rolf , Murty Bulusu A. R. C. , Spurr Paul R. , Fessner Wolf‐Dieter , Wörth Jürgen , Fritz Hans , Knothe Lothar , Prinzbach Horst
Published: July 2007

The stepwise route B from pagodanes to dodecahedranes was completed by double catalytic dehydrocyclization of saturated (alkylated) bisseco precursor substrates (2, 3, 5, 16). Based on pagodane, dodecahedranes (9, 10, 13, 14, 17) were obtained in up to 53% yield. Transannular C,C bond formation at the bisseco stage and partial (C–alkyl) or total (C–OR, C–CO2R) removal of substituent groups under the necessarily forcing reaction conditions constituted preparative limitations. Attempts at alternative ring closure methodologies (homo‐Norrish type II, homoenolization, carbene insertion) have remained unsuccessful.
Metallcarbonyl‐Synthesen, XXI. Einfache Synthese eines präparativ nützlichen Alkoxy(carbonyl)metallats
Authors: Herrmann Wolfgang A. , Mihalios Dimitrios , Öfele Karl , Kiprof Paul , Belmedjahed Fawzi
Published: July 2007

Metal Carbonyl Syntheses, XXI. – Straightforward Synthesis of a Synthetically Useful Alkoxy(carbonyl)metallate

Anionic methoxy complexes are formed upon carbonylation of ammonium perrhenate in methanol at 230–240°C. Thus, the dinuclear ionic complex [N(CH3)4][Re2(CO)6(μ‐OCH3)3] (2) results in 80% yield at CO pressures of ca. 100 bar, while the trinuclear derivative [N(CH3)4][Re3(CO)9(μ3‐OCH3)3(μ3‐OCH3)] (3) is due to lower pressure conditions (ca. 50 bar); 2 yields the bis(carbene) complex 4 of formula fac‐Re(CO)3L2I upon treatment with a bis(imidazolium) iodide, thus demonstrating that carbonylrhenium chemistry not necessarily depends on the availability of Re2(CO)10.
Organische Synthesen mit Übergangsmetall‐Komplexen, 60. Neuartige Benzoanellierung mit Carben‐Komplexen und Alkinen. – 2‐Oxybenzoanellierung von Cycloheptatrien über (Cycloheptatrienylmethyl)‐carben‐Komplexe von Chrom und Wolfram
Authors: Aumann Rudolf
Published: July 2007

Organic Syntheses via Transition Metal Complexes, 60. – Novel Type of Benzoanellation with Carbene Complexes and Alkynes. – 2‐Oxybenzoanellation of Cycloheptatriene via (Cycloheptatrienylmethyl)carbene Complexes of Chromium and Tungsten

We report on a three‐step procedure for the regiospecific 2‐oxybenzoanellation to cycloheptatriene by means of Fischer carbene complexes and alkynes. The first step involves the formation of (cycloheptatrienylmethyl)carbene complexes LnMC(OEt)CH2‐c‐C7H7 [1, LnM  Cr(CO)5 (a), W(CO)5 (b)] from the corresponding methylcarbene complexes and a tropylium salt. 1 reacts with the alkyne Et2NCCMe (2) to give the (E)‐ and (Z)‐1‐amino(1‐alkenyl)carbene complexes LnMC(NEt2)C(Me)C(OEt)CH2c‐C7H7 (3 and 4 resp.). Thermolysis of 3b [LnM = W(CO)5, 100°C, 5 h] finally leads to elimination of W(CO)5(Et2NH) (6b) and the regiospecific formation of the ethoxybenzocycloheptatrienes 5,7, and 8 in 92% total yield. The reaction is kinetically controlled and yields an isomeric ratio of 5:7:8 = 60:12:20% with the thermodynamically less stable isomer 5 predominating.
Cycloadditionen von 6H‐1,3,4‐Oxadiazin‐6‐onen (4,5‐Diazaα‐pyronen), 11. δ‐Chlor‐δ‐lactone aus γ‐Oxoketenen
Authors: Hegmann Joachim , Ditterich Elke , Hüttner Gerhard , Christl Manfred , Peters Eva‐Maria , Peters Karl , Von Schnering Hans Georg
Published: July 2007

Cycloadditions of 6H‐1,3,4‐Oxadiazin‐6‐ones (4,5‐Diaza‐α‐pyrones), 11. – δ‐Chloro δ‐Lactones from γ‐Oxo Ketenes

Prepared from 1,3,4‐oxadiazinone 1 with norbornene, cyclopentene, cyclopentadiene, and indene, the γ‐oxo ketenes 2, 5, 6, and 7 have been converted into the δ‐chloro δ‐lactones 3, 8, 9, and 10, respectively, by treatment with hydrogen chloride. The configuration of 10 has been determined by an X‐ray structural analysis. These pseudo chlorides prove to be stable against methanol. Only in the presence of sulfuric acid as catalyst 3 suffers methanolysis to yield diester 4. On thermolysis, the γ‐oxo ketenes are transformed into β‐lactones. In particular, 6 and 7 gave 13 and 12, respectively. Formed also on photolysis of 6, β‐lactone 13 partly isomerized to β‐lactone 14 on prolonged heating.
An Excellent Method for the Mild and Safe Oxidation of N‐Heteroaromatic Compounds and Tertiary Amines
Authors: Kaczmarek Lukasz , Balicki Roman , Nantka‐Namirski Pawel
Published: July 2007

Selective, mild and safe N‐oxidation of N‐heteroaromatic compounds and tertiary amines affording high product yields was achieved by using the H2O2‐urea/phthalic anhydride system.
1,3‐Diethoxy‐2‐azaindenylium‐hexachloroantimonat – ein destabilisiertes, cyclisches 1,3‐Dialkoxy‐2‐azaallyl‐Kation
Authors: Funke Wolfgang , Würthwein Ernst‐Ulrich
Published: July 2007

1,3‐Diethoxy‐2‐azaindenylium Hexachloroantimonate – a Destabilized, Cyclic 1,3‐Dialkoxy‐2‐azaallyl Cation

Regioselective alkylation at the carbonyl oxygen atom of 3‐ethoxyisoindolenone (3) by using a triethyloxonium salt yields the title salt 4, a new anti‐Hückel‐aromatic compound. The isomeric N‐acyliminium salt 5 is not observed. 13C‐ and 14N‐NMR‐spectroscopic methods indicate unusual charge distribution in the five‐membered ring of 4; on the basis of AM1 calculations, this is attributed to ring strain exerted on the 2‐azaallyl moiety. Antiaromatic π‐interactions in this formally 8π‐electron system are minimized by lengthening of the benzylic bonds, as indicated by AM1 data.
Enthalogenierung und regioselektive Phosphiniden‐Fragmentierung unsymmetrisch substituierter Methylenbisphosphane RXP–CH2–PXR′ mit Fe2(CO)9
Authors: Adelt Stephan , Bitterer Frank , Fischer Jörg , Rothe Jürgen , Stelzer Othmar , Sheldrick William S.
Published: July 2007

Dehalogenation and Regioselective Phosphinidene Fragmentation of Unsymmetrically Substituted Methylenebisphosphanes RXP‐CH2‐PXR′ with Fe2(CO)9

Reductive dehalogenation of the unsymmetrically substituted methylenebisphosphanes RXP–CH2‐PR′X [X = Cl, Br; R = tBu, NEt2; R′ = 2,4,6‐R”3C6H2 (R” = Me, tBu), NEt2, 2,6‐iPr2C6‐H3O, 2,6,4‐tBu2MeC6H2O] with Fe2(CO)9 affords, depending on the reaction conditions employed, phosphido complexes [μ2‐(RP‐CH2‐PR′)]Fe2(CO)6 (2) or phosphaalkene clusters (μ3‐PR′)(η2,μ3‐PRCH2)Fe3(CO)9(6) or [(μ‐PR)(η2,μ3PR′CH2)]Fe3‐(CO)9 (7), respectively, by regioselective phosphinidene fragmentation of the RP–CH2‐PR′ skeletons. The unstable cluster compounds [μ3‐PR′–CH2–PR)]Fe3(CO)9 (4) are formed as intermediate products. X‐ray structural analysis of 6c (R = tBu; R′ = NEt2) reveals a flat butterfly (μ3‐PR)Fe3 structure bridged by the phosphaalkene ligand tBuP = CH2 with a short P = C distance [177.2(4) pm].
Zur Existenz zwitterionischer λ5‐(Ammonioorganyl)tetrafluorosilicate: Synthese sowie Kristall‐ und Molekülstruktur von Tetrafluoro(pyrrolidiniomethyl)silicat
Authors: Tacke Reinhold , Becht Joachim , Mattern Günter , Kuhs Werner F.
Published: July 2007

On the Existence of Zwitterionic λ5‐(Ammonioorganyl)tetrafluorosilicates: Synthesis and Crystal and Molecular Structure of Tetrafluoro(pyrrolidiniomethyl)silicate

The zwitterionic tetrafluoro(pyrrolidiniomethyl)silicate (6) was synthesized by the reaction of trimethoxy(pyrrolidinomethyl)silane (7) with hydrogen fluoride in ethanol/hydro‐fluoric acid (yield 83%). 6 crystallizes in the space group P1/c with two crystallographically distinct molecules in the asymmetric unit. In both molecules the pentacoordinate silicon atom is surrounded by four fluorine atoms and one carbon atom, the latter being in an equatorial position. The coordination polyhedron of the silicon atoms can be described as a slightly distorted trigonal bipyramid. The zwitterionic structure was also proved for dissolved 6 (solution in CD3CN, NMR‐spectroscopic studies).
1,3‐Addition von Aziden an Azadecaboran: 6‐Azadecaboran‐4,9‐diyltriazene
Authors: Meyer Franc , Paetzold Peter , Englert Ulli
Published: July 2007

1,3‐Addition of Azides to Azadecaborane: 6‐Azadecaborane‐4,9‐diyltriazenes

nido‐NB9H12 (1) reacts with azides RN3 to form a coordinative B–N bond between B9 and N1 of RN3, accompanied by the α‐addition of the B4–H bond of 1 to the N3 atom of RN3. The products 2a, b (R = H, CH2Ph, respectively) thus contain an azadecaborane skeleton and a five‐membered unsaturated B2N3 ring with a common B–B edge. The product 2a crystallizes in the space group Pna21.
(E,Z)‐Gleichgewichte, 15. Synthesen und erhöhte Konfigurationslabilität von 2‐Iminoindan‐Derivaten mit Vorderseitenspannung
Authors: Knorr Rudolf , Ferchland Kathrin , Mehlstäubl Johann , Hoang Thi Phung , Böhrer Petra , Lüdemann Hans‐Dietrich , Lang Elmar
Published: July 2007

(E,Z) Equilibria, 15[1]. – Syntheses and Lability of the Configuration of 2‐Iminoindan Derivatives with Front Strain

Syntheses and properties are described for sterically shielded imines R2C = NR (3c, e, g–k), which are rather inert toward nucleophiles. Nucleophilic attack at the nitrogen atom of 3k is indicated by the formation of the azine 4. (E,Z) Configurational diastereotopomerization (anti/syn) is strongly dependent on N substituents [CH3, phenyl, 1‐naphthyl, acetyl, Si(CH3)3, cyano, SC6H5, SOC6H5, SO2C6H5, and nitro]. It is accelerated by front strain along the CN bond in 3a–c, e, g, h, j, and k and provides an energetic basis (by ΔG≠ and ΔΔG≠ values) for the gauging of force‐field parameters. This (E,Z) stereo‐mutation is characterized by a vanishing solvent dependence and a positive volume of activation (+10.2 cm3 mol‐1 for 3a). In contrast to other π acceptor substituents, the N‐nitro group in 31 retards (E,Z) interconversion.
Michael Adducts of (Alkynylcarbene)pentacarbonylchromium Complexes: Formation, Stereochemistry, and Thermal Rearrangement
Authors: Duetsch Michael , Stein Frank , Meijere Armin De , Lackmann Rolf , Pohl Ehmke , Herbst‐Irmer Regine
Published: July 2007

β‐Donor‐substituted α,β‐unsaturated chromium carbene complexes (CO)5CrC(OEt)C = CR(XR′n) (X = N, O, S; 3, 9, 11–16, 22–25) have been synthesized by Michael addition of amines, alcohols, and thiols to alkynylcarbene complexes (CO)5CrC‐(OEt)CCR (1). The configurations of the newly formed C–C double bonds have been determined by NOE/NOESY measurements and X‐ray crystal structure analysis. These vinylcarbene complexes lose one carbonyl ligand in refluxing tetrahydrofuran to give tetracarbonyl complexes (CO)4CrC(OEt)C = CR(XR′n) (X = N, O, S; 26–28).
Synthese und optische Eigenschaften endständig substituierter konjugierter Polyene mit Bicyclo[2.2.2]octan als Spacer
Authors: Effenberger Franz , Kesmarszky Thomas
Published: July 2007

Synthesis and Optical Properties of Terminally Substituted Conjugated Polyenes with Bicyclo[2.2.2]octane as Spacer

The conjugated polyenes 10, 11, and 17 respectively, with 9‐anthryl‐ and 2‐tetraphenylporphyrinyl (TPP) terminal groups and a bicyclooctane unit incorporated into the polyene chain were synthesized by Wittig olefinations. In all cases it was possible to obtain the all‐(E) compounds from the (E)/(Z)‐isomeric mixtures by chromatographic purification and several recrystallizations. From the UV/Vis spectra the separation of the TPP group and the polyene chain in 10, 11, and 17 can be deduced whereas in 10 and 11 the two conjugated double bonds are amalgamated into the anthryl group. In 17 the anthryl group is electronically separated from the polyene chain, and a selective excitation therefore is possible.
Organometall‐Imide – Höhervalente Derivate der d‐Metall‐Säure, 2. Alkyl‐, Aryl‐ und Cyclopentadienyl‐substituierte Molybdän(VI)‐ und Wolfram(VI)‐Imide
Authors: Radius Udo , Sundermeyer Jörg
Published: July 2007

Organometallic Imido Complexes – Highervalent Derivatives of the d‐Metal Acids, 2[4]. – Alkyl‐, Aryl‐, and Cyclopentadienyl‐Substituted Molybdenum(VI) and Tungsten(VI) Imido Complexes

CpMo(NtBu)2Cl (1a) and CpW(NtBu)2Cl (1b) (Cp = η5‐C5H5) react with organolithium reagents to form alkyl and aryl complexes of the type CpMo(NtBu)2R 2a–4a and CpW(NtBu)2R 2b–4b, resp., (R = Me, CH2SiMe3, Ph), highly volatile organo‐metallic compounds, which were isolated as analytically and spectroscopically pure oils by vacuum destillation. On the other hand, the protolysis reaction of 1a and 1b with excess of HCl gas affords monoimido complexes CpMo(NtBu)Cl3 (5a) and CpW(NtBu)Cl3 (5b), respectively.
Mixed amide thiolate complexes of zinc with low coordination number at the metal atom
Authors: Grützmacher Hansjörg , Steiner Matthias , Pritzkow Hans , Zsolnai Laszlo , Huttner Gottfried , Sebald Angelika
Published: July 2007

Three different thiophenoles 2,4,6‐(CF3)3C6H2SH (4), 2,4,6‐(iPr)3C6H2SH (5), and 2,6‐(Me3Si)2C6H3SH (6) with bulky sub‐stituents in ortho position were treated with Zn[N(SiMe3)2]2 (7) in a non‐coordinating solvent like CH2Cl2 or toluene to yield mixed amide thiolate zinc complexes Zn2[N(SiMe3)2]{S[2,4,6‐(CF)3C6H2]}3 (8), Zn3[N(SiMe3)2]2{S[2,4,6‐(iPr)3C6H2]}4 (9), and Zn2{S[2,6‐(Me3Si)2C6H3]}4 (10), respectively. These compounds comprise low‐coordinated zinc atoms. Initially, the reactions were performed in a 1:1 ratio of the reactants. However, in no reaction the expected {Zn[N(SiMe3)2](SR)}x (X = 1,2,3…) species were obtained but compounds which are richer in thiolate substituents (SR/NR2 > 1) even if a large excess of amide 7 was used. Distinct from these, the reaction between 7 and 2,6‐(iPr)2C6H3OH (14) in a 1:1 ratio afforded indeed dimer Zn2[N(SiMe3)2]2{O[2,6‐(iPr)2C6H3]}2 (15). The molecular structures of 8, 9, 10, and 15 in the crystal are elucidated by X‐ray structural analyses and compared with proposed structures in solution based on multinuclear NMR experiments.