bluuebunny/crossref_metadata_2025 huggingface dataset:
Metallcarbonyl‐Synthesen, XX. Einfache Methode zur Darstellung von Tc(CO)3‐Komplexen: Synthese und Struktur der neuartigen Technetium(I)‐Clusterverbindung Na[Tc3(CO)9(OCH3)4] mit Cuban‐Struktur
Authors: Herrman Wolfgang A. , Alberto Roger , Bryan Jeff C. , Sattelberger Alfred P.
Published: July 2007

Metal Carbonyl Syntheses, XX. – Simple Method for the Preparation of Tc(CO)3Complexes: Synthesis, Structures, and Reactivity of the Novel Cubane‐Type Cluster Na[Tc3(CO)9(OCH3)4]

Carbonyltechnetium complexes of type LTc(CO)3are accessible along a simple route from Na[Tc3(CO)9(OCH3)4] (2) which represents a novel alkoxy complex of cubane‐type geometry (single‐crystal X‐ray diffraction study).2is an isolable product of the incomplete carbonylation of sodium pertechnetate (1) conducted in methanol. Under carbon monoxide pressure,2yields the binary metal carbonyl Tc2(CO)10(3), pentamethyl‐cyclopentadiene gives the halfsandwich complex (η5‐C5Me5)Tc(CO)3(4), and with benzene/hydrochloric acid the ionic complex [(η6‐C6H6)Tc(CO)3]Cl (5) is formed.
Cycloadditions, 47. A Route to Functionalized Cyclic Ethers by Intramolecular Cycloadditions of Unsaturated Nitro Ethers
Authors: Hassner Alfred , Dehaen Wim
Published: July 2007

A convenient conversion of aldehydes via nitroolefins 2 into cyclic ethers 6 fused to an isoxazoline ring involves formation of unsaturated nitroalkyl ethers 4 and subsequent intramolecular cycloaddition of an in situ‐formed nitrile oxide olefin. The cyclization proceeds with stereoselective formation of trans over cis isomers in the tetrahydrofuran series and opposite stereoselectivity in the tetrahydropyran and hexahydrooxepine series, depending on the substituent R in the original nitro compound, thus providing access to stereoselectively functionalized cyclic ethers.
Anticancer Agents, 15. Squaric Acid Diethyl Ester: A New Coupling Reagent for the Formation of Drug Biopolymer Conjugates. Synthesis of Squaric Acid Ester Amides and Diamides
Authors: Tietze Lutz F. , Arlt Michael , Beller Matthias , Gl üsenkamp Karl‐Heinz , Jähde Eckhard , Rajewsky Manfred F.
Published: July 2007

Reaction of squaric acid diethyl ester (1) with a slight excess of a primary or secondary amine 2 in ethanol, dichloromethane or aqueous buffer (pH 7) at 20°C for 0.3–12 h gives the squaric acid amide esters 3 in mostly excellent yields. Treatment of 3 with amines 2 or 4 in organic solvents in the presence of triethylamine or in aqueous buffer (pH 9) leads to the corresponding symmetrical and unsymmetrical squaric acid diamides 5, respectively. The reaction can be followed by UV spectroscopy.
Hydroboration of Bis(alkenylcyclopentadienyl)zirconium Dichlorides
Authors: Erker Gerhard , Aul Rainer
Published: July 2007

The reaction of allylcyclopentadienyllithium with 0.5 molar equivalents of MCl4(thf)2 (MZr, Hf) furnished the (η5‐C5H4CH2CHCH2MCl2 complexes 3a (Zr) and 3b (Hf), which cleanly added 9‐borabicyclo[3.3.1]nonane (9‐BBN) to form [η5‐C5H4(CH2)3(9‐BBN)]2MCl2 (10a, b). Treatment of 3 with butadiene‐magnesium led to coupling of one Cp‐bonded allyl unit with butadiene to give 5; the remaining CpCH2CHCH2 group underwent clean H[B(C8H14)] addition when exposed to the 9‐BBN hydroboration reagent. (Alkenyl‐Cp)2ZrCl2 complexes (9a – d) were prepared starting from fulvenes by deprotonation with the help of LDA and reaction with ZrCl4(thf)2. The complexes [η5‐C5H4CHC(CH3)R]2ZrCl2 9b (RCH3) and 9c (RPh) added 9‐BBN to give [η2‐C5H4CH(9‐BBN)CH(CH3)R]2ZrCl2 12 (RCH3, rac;‐/meso;‐ ≈︁ 1:1) and 13 (RPh, threo;‐/erythro;‐ ≈︁ 1:1). The mixtures of diastereoisomers were in each case separated by fractional crystallization. The stereochemical assignments of complexes rac;‐12 and meso;‐12 were achieved by means of the stereochemistry of polypropylene formed at the 12/methylalumoxane‐derived homogeneous Ziegler‐type olefin polymerization catalysts. At – 50°C the catalyst from the achiral meso;‐12 precursor produced isotactic polypropylene only by means of “chain end control” (σ ≈︁ 0.7), whereas the use of rac;‐12 led to a pronounced participation (≈︁ 30%) of effective “enantiomorphic site control” (α=0.95) in the CC‐coupling reaction.
Neue Synthesen für Ibuprofen und Naproxen
Authors: Wolber Erwin K. A. , Rüchardt Christoph
Published: July 2007

New Syntheses of Ibuprofen and Naproxen

A new route for the synthesis of α‐arylpropionic acids, in particular for the two most important non‐steroidal antiinflammatory compounds Ibuprofen (5) as well as racemic and optically active Naproxen (12), has been developed. N‐(1‐Arylethyl)formamides 2, 9 are dehydrated to the corresponding isocyanides 3, 10, and these are rearranged by flash pyrolysis to α‐arylpropionitriles 4, 11 which are converted into α‐arylpropionic acids 5, 12 by hydrolysis under standard conditions. The intermediate 1‐(6‐methoxy‐2‐naphthyl)‐ethylamine is resolved via its tartrate or mandelic salts.
Organometall‐Imide – Höhervalente Derivate der d‐Metall‐Säuren, 1 Neue Organometall‐Imide des Molybdäns und Wolframs — die direkte Einführung der Cyclopentadienyl‐Gruppe durch Maskierung der hohen Oxidationsstufe
Authors: Sundermeyer Jörg
Published: July 2007

Organometallic Imido Complexes – Higher Valent Derivatives of the d‐Metal Acids, 1. – New Organometallic Imido Complexes of Molybdenum and Tungsten – Direct Introduction of the Cyclopentadienyl Group by Masking the High‐Oxidation State

The molybdenum(VI)bis(tert‐butylimido) complex MO(NtBu)2‐Cl2 is converted into the novel organomolybdenum(VI) derivative (η5‐C5H5)MO(NtBu)2Cl (1) in excellent yield. The preparation of the pyridine complex W(NtBu)2Cl2py2 (2) provides a convenient starting material for an effective synthesis of the related complex (η5‐C5H5)W(NtBu)2Cl (4).
Tin for Organic Synthesis, 5 A New and Regioselective Synthesis of Aromatic Diazene Derivatives
Authors: Neumann Wilhelm P. , Wicenec Christian
Published: July 2007

A new method for the preparation of aromatic diazene derivatives 3a — 1, 5, 7a, b, 9 under very mild conditions is described. The reaction of trialkylarylstannanes with nitro‐substituted benzenediazonium tetrafluoroborates leads, by strict ipso substitution, to the corresponding diaryldiazenes in satisfactory to high yields. Due to the excellent leaving group quality of the stannyl group azo compounds may be prepared which are not accessible by normal electrophilic azo coupling. The products can be valuable precursors, obtained by reduction to the amines or other derivatizations, for consecutive aromatic compounds.
Cathodic Reduction of 1‐Nitroalkenes to Oximes and Primary Amines
Authors: Wessling Michael , Schäfer Hans J.
Published: July 2007

1‐Nitroalkenes are reduced in high yields at ‐0.3 to ‐0.5 V (vs. SCE) at a mercury or graphite cathode to oximes. At higher cathodic reduction potentials (‐ 1.1 V) primary amines are selectively obtained in fair yields. Nitroalkadienes are selectively reduced at the double bond conjugated with the nitro group to either the oxime or amine.
Gas‐Phase Substitution of Dichloro‐ and Dibromoethene by Ammonia and Amines via Radical Cations. A Kinetic Study by FT‐ICR Spectrometry
Authors: Thölmann Detlef , Flottmann Dirk , Grützmacher Hans‐Friedrich
Published: July 2007

The gas‐phase reactions of the three isomeric dichloroethene radical cations 1+.‐3+. with NH3 and of the neutral species 1–3 and the isomeric 1,2‐dibromoethenes 4 and 5 with CH3‐NH2+. and (CH3)2NH+., respectively, are studied by Fourier‐Transform Ion‐Cyclotron‐Resonance (FT‐ICR) mass spectrometry. A chloro substituent in 1+.‐3+. is replaced by NH3 in a fast reaction, yielding C2H5NCl+ ions. These substitution reactions are very fast and occur nearly at the collision limit. The 1,1‐dichloroethene radical cations 3+. exchange successively both Cl substituents, yielding C2H7N2+ ions and eventually cluster ions N2H7+. Substitution takes place also by the reaction of neutral haloethenes 1–5 with amine radical cations, although at very different rates. The efficiencies of the reactions of CH3HN2+. with 1–5 are quite large, but those of the reactions of (CH3)2NH+. with 1 and 2 are < 1% and reach only ≤ 10% even in the case of the bromoethenes 4 and 5. 1,1‐Dichlorethene (3) does not react at all. An addition‐elimination mechanism is proposed for all these reactions, giving rise to the formation of intermediate β‐distonic ammonium ions. This reaction path and the stability of the intermediates are supported by MNDO calculations. However, the intermediate β‐distonic ions have to isomerize further by hydrogen shifts before the product ions are eventually formed. MNDO calculations support the assumption that the slow reactions of (CH3)2NH+. with the haloethenes are due to slow rearrangements within the initially formed distonic ions, which have to precede the loss of Cl.
Kurzmitteilung / Short Communication A Convenient Preparation of Acetone Solutions of Dimethyldioxirane
Authors: Adam Waldemar , Bialas Joachim , Hadjiarapoglou Lazaros
Published: July 2007

A novel simplified procedure affords consistently 0.09‐0.10 M solutions of distilled dimethyldioxirane in acetone; other than control of the reaction temperature below 15° and vigorous mechanical stirring, no other precautions are maniatory.
Stereoisomeric Dichloro[1‐(hydroxyphenyl)‐2‐phenyl‐1,2‐ethanediamine]platinum(II) Complexes, Part I: Synthesis
Authors: Müller Richard , Gust Ronald , Schönenberger Helmut , Klement Ulrich
Published: July 2007

Various erythro‐ and threo‐configurated dichloro[1‐(hydroxyphenyl)‐2‐phenyl‐1,2‐ethanediamine]platinum(II) complexes were synthesized with the hydroxy group located in either the 2‐, 3‐, or 4‐position of the phenyl ring (38–40). The diastereoisomeric 1‐(3‐hydroxyphenyl)‐2‐phenyl‐1,2‐ethanediamines (31, 32) and threo‐1‐(2‐hydroxyphenyl)‐2‐phenyl‐1,2‐ethanediamine (30) were obtained by reduction of the 1,2‐diazidoethanes and subsequent ether cleavage. The configuration of the threo‐1,2‐diazido‐1‐(2‐methoxyphenyl)‐2‐phenylethane (5) was elucidated by X‐ray analysis. The reduction of the erythro‐1,2‐diaryl‐1,2‐diazidoethanes, substituted with a methoxy group in ortho or para position, results in elimination reactions with formation of side products. The desired 1,2‐diaryl‐1,2‐ethanediamines were finally synthesized via either an aziridine derivative 21 or by reduction of the respective dioximes 27, 28. The diamine ligands were converted into the corresponding dichloroplatinum(II) complexes 38 – 40.
Preparation and Selected Reactions of t‐Butyl 2‐Methylene‐3‐oxoalkanoates
Authors: Martin H. , Hoffmann R. , Gassner Andreas , Eggert Ulrike
Published: July 2007

The title class of 1,1‐diactivated ethylenes has been prepared in two steps from aldehydes and t‐butyl acrylate by (i) DABCO‐catalyzed coupling to give t‐butyl 2‐(hydroxyalkyl)‐2‐propenoates 11 and (ii) low‐temperature Jones oxidation, followed by swift work up at low temperature. The resulting t‐butyl 2‐methylene‐3‐oxoalkanoates 12 are stabilized by sterically demanding and also by aromatic groups R. For primary unhindered alkyl groups, stability is low. The compounds enter into Michael reactions, hetero Diels‐Alder additions with enol ethers, and self‐dimerization.
Photoisomerisierung von Halogendimethylsulfiden
Authors: Maier Günther , Flögel Ulrich , Reisenauer Hans Peter , Andes Hess B. , Schaad Lawrence J.
Published: July 2007

Photoisomerization of Halogenodimethyl Sulfides

Photolysis of iodo‐ (3a), bromo‐ (3b), and chlorodimethyl sulfide (3c) in an argon matrix at 12 K gives rise to isomeric species 4a — c. Ab initio calculations indicate that in these isomers the halogen has been removed from the carbon atom and forms a weak bond to forms a weak bond to the sulfur atom. This conclusion is based on the comparison of observed and calculated IR spectra of the photoisomers.
Heterocumulene, 6 C5OS (5‐Thioxo‐1,2,3,4‐pentatetraen‐1‐on) ‐ Darstellung und spektroskopische Eigenschaften
Authors: Maier Günther , Schrot Jürgen , Reisenauer Hans Peter
Published: July 2007

Heterocumulenes, 6. — C5OS (5‐Thioxo‐1,2,3,4‐pentratetraen‐1‐one) — Preparation and Spectroscopic Properties

C5OS (8) is prepared by flash pyrolysis of the precursor molecules 4, 5, and 7 and by matrix photolysis of 7. The IR‐ and UV/Vis spectra of matrix‐isolated 8 are reported.
On the Utility of 13C (CPMAS) NMR in Conformational Studies of Simple Hydroxy‐, Alkoxy‐ and Acetoxycalixarenes in the Solid State
Authors: Liang Tze‐Ming , Laali Kenneth Khosrow
Published: July 2007

The potentiality of 13C (CPMAS) NMR as a conformational probe for the oligomeric macrocycles p‐(tert‐butyl)calix‐[n]arenes (n = 4, 6, 8) and their alkoxy/acetoxy derivatives in the solid state is explored.
Orotate Complexes, II1) Preparation and Crystal Structures of Calcium and Zinc Orotate(2‐) Hydrates
Authors: Kumberger Otto , Riede Jürgen , Schmidbaur Hubert
Published: July 2007

From aqueous solutions containing orotate (dianion of 1) and calcium or zinc ions in the molar ratio of 2:1, metal orotate (2‐) hydrates are readily obtained in crystalline form at pH 9.0 and 5.4, respectively. According to an X‐ray crystal structure analysis, calcium orotate tetrahydrate forms a one‐dimensional coordination polymer with each orotate ligand coordinated to no less than three neighboring calcium atoms. In this cation triple, the orotate(2‐) anion acts as a carboxylate‐O/amide‐N‐chelating group for the central calcium ion, but also as a carboxylate‐O/O‐chelating group for the first neighboring calcium ion, and as a terminal amide‐O donor for the second. Each calcium ion is thus octacoordinated and linked to three orotate(2‐) anions and three water molecules. The fourth water molecule is only engaged in hydrogen bonding. The new zinc orotate(2‐) phase features Zn(Or)(H2O)4 units. For the hexacoordinate zinc atom bearing four water molecules the orotate(2‐) ligand also acts as an O/N‐chelating group. Unlike a discrete Zn(Or)(H2O)4 H2O phase reported earlier, the lattice of the new phase contains further disordered water of crystallization, with the overall composition approaching Zn(Or) 5.5 H2O. The apparent stability of the M(Or) units probably reflects the well‐documented carrier function of the orotate ligand for certain divalent metal ions in biological systems.
Organophosphorverbindungen, 511) Phosphatriafulvene – Phosphaalkene mit inverser Elektronendichte2)
Authors: Fuchs Eberhard , Breit Bernhard , Heydt Heinrich , Regitz Manfred , Schoeller Wolfgang , Busch Thilo , Krüger Carl , Betz Peter
Published: July 2007

Organophosphorus Compounds, 511). – Phosphatriafulvenes – Phosphaalkenes with Inverse Electron Density2)

Peterson olefination of the sterically hindered cyclopropenones 1 with the lithium phosphides 2 yields the so far unknown phophatriafulvenes 3 and 4, which possess inverse electron densities. They are characterized by transition metal complex formation (→7, 8). Acylation of 3a with the carboxylic acid chlorides 11 leads to a great variety of P‐acylphosphatriafulvenes 13a‐s. They partly dimerize under formation of the 1,3‐diphosphacyclobutanes 13 ⇌ 14.
Photoinduced Reactions of Cr(CO)3‐Coordinated 1,3,5‐Cycloheptatriene: [6 + 2] Cycloaddition with an Alkyne and Catalytic 1,6‐Hydrogenation
Authors: Fischler Ingrid , Grevels Friedrich‐Wilhelm , Leitich Johannes , Özkar Saim
Published: July 2007

Irradiation of Cr(CO)3(η6‐1,3,5‐cycloheptatriene) (1) in the presence of bis(trimethylsilyl)ethyne results in [6 + 2] cycloaddition of the alkyne to the cycloheptatriene ligand, yielding Cr(CO)3(η4:2‐7,8‐bis(trimethylsilyl)bicyclo[4.2.1]nona‐2,4,7‐triene} (2, 60% yield, Φ=0.08), which upon oxidative decomposition with Ce(IV) releases the organic cycloadduct, 7,8‐bis‐(trimethylsilyl)bicyclo[4.2.1]‐nona‐2,4,7‐triene (3). Photocatalytic hydrogenation of 1,3,5‐cycloheptatriene in the presence of complex 1 affords 1,3‐cycloheptadiene. This process involves 1,6‐addition of hydrogen, as demonstrated by using D2.
Small and Medium Rings, 791) 4‐Azatetracyclo[3.3.0.02,8.03,6]octanes: New Hetereocycles by Addition of Sulfonyl Azides to 7‐Substituted Norbornadienes – Experimental Verification of σ Interactions in the Norbornane Skeleton
Authors: Huda Egbert , Martin Hans‐Dieter , Mayer Bernhard , Somnitz Karl‐Heinz , Steigel Alois , Haddad Hatim , Distefano Guiseppe , Modelli Alberto
Published: July 2007

The reaction of six 7‐substituted norbornadienes with seven sulfonyl azides has been investigated. The products consist of either the novel azatetracyclic system 1 or the stereoisomeric bicycles 2 or of a mixture of them. The chemical behaviour of 1 has been studied. Mechanistically the results may be rationalized within the frame of the Mazzocchi‐Houk model. The theoretical predictions of this model, concerning the π*and σ* energies, were confirmed experimentally by using electron‐transmission spectroscopy.
Substituted C3BN2 Heterocycles from Trialkylboranes and Nitriles
Authors: Yalpani Mohamed , Köster Roland , Boese Roland
Published: July 2007

The reaction of trialkylboranes, e. g. triethylborane (Et3B), tripropylborane (Pr3B), or 9‐alkyl‐9‐borabicyclo[3.3.1]nonane [alkyl‐BBN; alkyl=Et, 1‐methylpropyl, 1‐methybutyl/1‐ethylpropyl], with either aceto‐, propio‐, butyro‐, pivalo‐, and benzonitrile gives, depending on the reaction conditions used or the nitrile employed, either the substituted diazoniadibora‐tetidines (1 a—c), products of partial hydroboration, or by condensation of two or three nitrile molecules, with or without a concomitant hydroboration, the C3BN2 heterocycles 2a—c, 8a/b, 9a—d, and 10a/b (X‐ray structure analyses of 2a and 10b).
Hydrierwärmen, IV. Zur Frage der Homoaromatizität von Norcaradien und Cycloheptatrien
Authors: Roth Wolfgang R. , Klärner Frank‐Gerrit , Siepert Gerd , Lennartz Hans‐Werner
Published: July 2007

Heats of Hydrogenation, IV. — Homoaromaticity in Norcaradiene and Cycloheptatriene

By comparison of the heats of hydrogenation of fixed norcaradienes with analogous cyclobutane derivatives and from the difference of experimental heats of formation with values calculated by force‐field methods the homoaromatic stabilization of norcaradienes and cycloheptatrienes are calculated and compared with the equilibrium position of the respective valence isomers.
Chromium(II)‐Mediated Intermolecular Free‐Radical Carbon — Carbon Bond Formation
Authors: Tashtoush Hasan I. , Sustmann Reiner
Published: July 2007

Chromium(II) complexes are found to be effective mediators for intermolecular free‐radical C–C bond formation. Thus, Cr(en)22+ species react with alkyl halides to generate the corresponding alkyl radicals which are readily trapped with electron‐deficient alkenes to afford the coupling products.
Zum Kenntnisstand der 1,3,5‐Triaza‐2,4‐diphospha‐1,4‐pentadiene
Authors: Detsch Ralph , Niecke Edgar , Nieger Martin , Reichert Franz
Published: July 2007

On the Knowledge of the 1,3,5‐Triaza‐2,4‐diphospha‐1,4‐pentadienes

Herrn Professor Heinrich Puff zum 70. Geburtstag gewidmet

Nucleophilic substitution reactions of the chloro(arylimino)‐phosphane 1 yield the NH‐functional amino(imino)phosphanes Mes*NPNHR (R = Mes, Ad, CPh3) 2d—f. Upon further reaction with 1 they are converted into the 1,3,5‐triaza‐2,4‐diphospha‐1,4‐pentadienes Mes*NPN(R)PNMes* (R = Mes, Ad) 4d, e and Mes*NPN(Mes*)PNCPh3 5. According to crystal structure determinations all compounds 4a, d, e, 5 exhibit S conformation in the solid state. In addition to the “exo‐endo” arrangement of the substituents (4a, 5) in the case of 4d, e the “endo‐endo” conformation is observed for the first time. In solution, 4d, e and 5 are subject to dynamic rearrangements, whose mechanism is proven by NMR studies of partially 15N‐enriched samples. The reaction of 4a with NorM(CO)4 (M = Cr, Mo) or Ni(CO)4 yields the metallaazadiphosphetidine complexes 6a—c Mes*NPN(tBu)PNMes*M(CO)n [M(CO)n = Cr(CO)4, Mo(CO)4, Ni(CO)2]. The crystal structure of 6a (“exo‐endo‐W”) is described.
Bis(cyclopentadienyl)methan‐verbrückte Zweikernkomplexe, IV. Synthese, Struktur und Reaktivität von Zweikernkomplexen des Rhodiums und Iridiums in der Oxidationsstufe +I und +III mit dem Bis(cyclopentadienyl)methan‐Dianion als Brückenliganden
Authors: Werner Helmut , Treiber Monja , Nessel Angelika , Lippert Ferdinand , Betz Peter , Krüger Carl
Published: July 2007

Bis(cyclopentadienyl)methane‐Bridged Dinuclear Complexes, IV[1]. — Synthesis, Structure, and Reactivity of Dinuclear Rhodium and Iridium Complexes in the Oxidation State +I and +III with the Bis(cyclopentadienyl)methane Dianion as Bridging Ligand

The rhodium compounds [CH2(C5H4)2][Rh(L)(C2H4)]2 (2, 4) were prepared from [RhCl(L)(C2H4)]2 (1, 3) and CH2(C5H4)2Li2 in 92 and 73% yield, respectively. The reaction of 4 with Cl2, Br2, and I2 led to the almost quantitative formation of the dihalogeno derivatives [CH2(C5H4)2][RhX2(PiPr3)]2 (6–8), which on treatment with excess NaBH4 and methanol gave the dihydride [CH2(C5H4)2][RhH2(PiPr3)]2 (10). From [RhCl(C8H14)2]2 (12), PiPr3, and CH2(C5H5)2 the chloro(hydrido)rhodium complex [CH2(C5H4)2][RhH(Cl)(PiPr3)]2 (13) was obtained. Protonation of 10 with CF3CO2H in the presence of NH4PF6 gave the PF6 salt of the hydrido‐bridged cation {[CH2(C5H4)2]‐[RhH(PiPr3)]2(μ‐H)}+ (14) of which the crystal structure was determined. In solution, fluxional behavior of the cation was observed. The dimethyl compound [CH2(C5H4)2][Rh(CH3)2‐(PiPr3)]2 (17), prepared from 6, 7, or 8 and LiCH3 or CH3MgI in 80% yield, reacted with CF3CO2H at — 78° C to give the tri‐fluoroacetato derivative 18; this on treatment with P(OMe)3 and dmpe formed the dicationic complexes 19 and 20, respectively. The dinuclear iridium compounds [CH2(C5H4)2]‐[Ir(olefin)2]2 (26, 27) and [CH2(C5H4)2][Ir(C8H12)]2 (28) were prepared from [IrCl(L)2]2 (23–25) and CH2(C5H4)2Li2 and used for the synthesis of {[CH2(C5H4)2][IrX2]2}n (29, 30). Compounds 29 and 30 served as starting materials for the preparation of the dinuclear derivatives [CH2(C5H4)2][IrX2(L)]2 (31–34) and {[CH2(C5H4)2][IrBr2]2(μ‐dipy)} (35) and finally also for the dihydrido complex [CH2(C5H4)2][IrH2(PiPr3)]2 (36).
Neue Synthesen für isomerenreine Allyl‐ und Propargylcyanide durch Isocyanid‐Cyanid‐Umlagerung[1]
Authors: Wolber Erwin K. A. , Schmittel Michael , Rüchardt Christoph
Published: July 2007

New Syntheses of Isomerically Pure Allyl and Propargyl Cyanides by Isocyanide‐Cyanide Rearrangement[1]

A new route for the synthesis of isomerically pure allyl and propargyl cyanides has been developed. Allylic amines are synthesized from the corresponding alcohols by Mitsunobu or by Overman reaction. Formylation with formic acid derivatives provides N‐substituted formamides, which are dehydrated to isocyanides. 1,2‐Sigmatropic rearrangement by flash pyrolysis provides the isomerically pure allyl and propargyl cyanides.
Verbindungen des Germaniums und Zinns, 10[1] Thermolyse eines Cyclotristannans: Stannylen‐ versus Distannen‐Reaktionen
Authors: Weidenbruch Manfred , Schäfer Annemarie , Kilian Hartmut , Pohl Siegfried , Saak Wolfgang , Marsmann Heinrich
Published: July 2007

Compounds of Germanium and Tin, 10[1]. — Thermolysis of a Cyclotristannane: Stannylene versus Distannene Reactions

Hexakis(2,4,6‐triisopropylphenyl)cyclotristannane (1), first described by Masamune and Sita, is easily accessible by treatment of tin(II) chloride with 2,4,6‐triisopropylphenylmagnesium bromide. The equilibrium between 1 and its cleavage products bis(2,4,6‐triisopropylphenyl)stannylene (2) and tetrakis(2,4,6‐triisopropylphenyl)distannene (3) in toluene has been followed by 119Sn‐NMR spectroscopy at elevated temperatures. Stannylene 2 can be trapped by open‐chain or cyclic diketones as well as by 1,3‐dienes. Reaction of 3 with phenylacetylene proceeds in a [2 + 2] fashion to provide the 1,2‐distannacyclobutene derivative 5 whose structure was confirmed by X‐ray crystallography.
Room‐Temperature C–F Bond Activation of Hexafluorobenzene by a Tailor‐Made Pt(0) Intermediate, [(dtbpm)Pt(0)]
Authors: Hofmann Peter , Unfried Günter
Published: July 2007

Reductive elimination of neopentane from cis‐hydridoneopentyl[η2‐bis(di‐tert‐butylphosphanyl)methane]platinum (II), (dtbpm)Pt(Np)(H) (1), allows to generate the 14‐electron fragment [(dtbpm)Pt(0)] (2) at ambient temperature. This highly reactive intermediate is capable of activating C–F bonds of hexafluorobenzene, yielding exclusively the C–F insertion product (dtbpm)Pt(C6F5)F (3).
Spaltung sperriger Diarylditelluride mit Brom und Iod[1]; Strukturbestimmung an Et4N+ 2,4,6‐(i‐C3H7)3C6H2TeI−2
Authors: Mont Wolf‐Walther Du , Meyer Hans‐Ulrich , Kubiniok Silvia , Pohl Siegfried , Saak Wolfgang
Published: July 2007

Cleavage of Bulky Diaryl Ditellurides with Bromine and Iodine; Crystal Structure of Et4N+ 2,4,6‐(i‐C3H7)3C6H2TeI−2

Bis(2,4,6‐triisopropylphenyl) ditelluride (1a), obtained from 2,4,6‐triisopropylphenylmagnesium bromide with tellurium followed by oxidation with oxygen, and bis(2,4,6‐tri‐tert‐butylphenyl) ditelluride (1b) react with equimolar amounts of bromine and iodine to provide new monomeric arenetellurenyl halides 2,4,6‐R3C6H2TeX (2a, b, 3a, b: R = i‐C3H7, t‐C4H9; X = Br, I). Both tellurenyl iodides are thermally more stable than the corresponding bromides. Green 2,4,6‐(i‐C3H7)3C6H2TeI (3a) reacts with Et4N+I− to give the stable, red adduct Et4N+ 2,4,6‐(i‐C3H7)3C6H2TeI−2 (4a). An X‐ray crystal structure determination of 4a revealed a T‐shaped structure of the hypervalent aryldiiodotellurate(II) anion. Iodide‐ion transfer between aryldiiodotellurate(II) and arenetellurenyl iodide is a fast process (1H‐NMR time scale). 125Te‐NMR data of this anion and of tellurenyl halides are compared with those of the ditellurides and of lithium benzenetellurolates (LiTeR·(THF)x).
Insertions‐, Isomerisierungs‐ und Cycloadditions‐Reaktionen lithiierter Aminofluorsilane
Authors: Walter Simone , Klingebiel Uwe , Noltemeyer Mathias
Published: July 2007

Insertion, Isomerization, and Cycloaddition Reactions of Lithiated Aminofluorosilanes*

The lithium derivative 2 of (di‐tert‐butylfluorosilyl)(fluorodi‐isopropylsilyl)amine (1) reacts with benzoyl chloride to form the imines 3I and 3II in an insertion reaction. LiF elimination from 2 leads to the cyclodisilazane [(CMe3)2SiFN—Si(CHMe2)2]2 (4). The fluorine atom of the SiF(CHMe2) group in 1 can be substituted by means of LiOSiMe3 to yield 5. The lithium derivative of 5 (6) is a dimer with very short Li—F distances. The lithium derivative 6 reacts with benzaldehyde in a [2 + 2] cycloaddition to give an (SiNCO) four‐membered ring compound (7), which thermally decomposes to yield the imine 8 and a cyclosiloxane, A fluorine/chlorine exchange is observed when Me3SiCl is added to the lithium derivative 6. The resulting unstable lithium derivative of an aminochlorosilane eliminates LiCl to form the cylcodisilazane 9. According to a crystal structure determination the formation of 9 involves isomerization of the intermediate iminosilane followed by dimerization.
Polyol‐Metall‐Komplexe, II[1] Kupfer(II)‐Komplexe mit mehrfach deprotoniertem Ethylenglycol, Anhydro‐erythrit oder Methyl‐α‐D‐mannopyranosid als Liganden
Authors: Habermann Norbert , Jung Gisela , Klaassen Markus , Klüfers Peter
Published: July 2007

Polyol Metal Complexes, II[1]. – Copper(II) Complexes with Multiply Deprotonated Ethylene Glycol, Anhydro‐erythritol, or Methyl α‐D‐Mannopyranoside as Ligands

Violet to blue crystals of the polyolate cuprates Li2[Cu(eth2−)2] · 6 H2O (1), A2[Cu(eryAn2−)2] · 4 H2O, A = Na (2a), K (2b), and Li3[Cu(Me‐α‐manpH2[2,3]2−)(Me‐α‐manpH[2,3,4]3−)] · 5 H2O (3) with anionic ligands derived from ethylene glycol (ethH2), anhydro‐erythritol (eryAnH2), or methyl α‐D‐mannopyranoside (Me‐α‐manpH4), resp., are formed by the reaction of alkali metal hydroxide with cupric hydroxide and the proper polyol in aqueous solution. X‐ray crystal structure determinations were carried out on all new compounds. In 1–3 deprotonated polyols form chelate complexes with copper ions; additonally, the polyolate ligands bind to alkali metal ions and/or they act as acceptors in asymmetric hydrogen bonds. In 3 one of the two O‐2,O‐3‐mannosidato ligands is present as a trianion: O–4 is deprotonated, too, but instead of copper, the O–4‐alkoxide group binds two lithium ions. The new compounds are discussed with respect to copper complexes of cellulose in alkaline media.
Synthese und Struktur von 4,4′‐Bis[phenyl(triphenylphosphonio)methyl]‐biphenyl‐diperrhenat
Authors: Hesse Detlev , Roesky Herbert W. , Noltemeyer Mathias
Published: July 2007

Synthesis and Structure of 4,4′‐Bis[phenyl(triphenylphosphonio)methyl]biphenyl Diperrhenate

(tBu)2Si(OReO3)2 (1) reacts with Ph3P = CPh2 (2) to form the title compound [4‐Ph3PC(Ph)C6H4]2(ReO4)2 (3), the structure of which is confirmed by an X‐ray structural analysis.
4,4′‐Distyrylazobenzol als Mesogen
Authors: Kosteyn Frank , Zerban Georg , Meier Herbert
Published: July 2007

4,4′‐Distyrylazobenzene as Mesogen

From 3,4‐dihydroxybenzaldehyde (1) the tetraalkoxy‐substituted 4,4′‐distyrylazobenzenes (E,E,E)‐5a – c are synthesized. A similar reaction sequence leads from ethyl 3,4,5‐trihydroxy‐benzoate (6) to the hexaalkoxy‐substituted 4,4′‐distyrylazobenzenes (E,E,E)‐11 b, c. With the exception of 5a all products show thermotropic LC properties. Smectic phases have been characterized by polarizing microscopy and by differential scanning calorimetry.
Synthese und Eigenschaften von σ‐verbrückten Anthracen‐Viologenen[1]
Authors: Effenberger Franz , Götz Gunther , Bäuerle Peter
Published: July 2007

Synthesis and Properties of of σ‐Bridged Anthracene‐Viologens[1]

The synthesis of the donor‐acceptor compounds 2, 7, and 12 where the anthracene donor and the viologen acceptor are linked by a saturated bridge (polymethylene or the bicyclo[2.2.2]octanyl moiety) is described. While the preparation of 2a–c is straightforward, new procedures for the synthesis of the bicyclo compounds 7 and 12 had to be developed. Unexpectedly, the viologens 13d, e could be obtained by direct nucleophilic substitution of the corresponding tertiary and neopentyl‐type alkyl tosylates with 4,4′‐bipyridine. By comparison of the emission spectra of the compounds 2a and 12a, b the strong fluorescence quenching indicates an electron transfer from the donor to the acceptor.
Metallkomplexe in Anorganischen Matrices, 8[1] Chromtricarbonyl‐Komplexe von Benzoylacetonat‐substituierten Titan‐, Zirkonium‐ und Aluminium‐Alkoxiden
Authors: Schubert Ulrich , Buhler Hermann , Hirle Brigitte
Published: July 2007

Metal Complexes in Inorganic Matrices, 8[1]. – Chromium Tricarbonyl Complexes of Benzoylacetonate‐Substituted Titanium‐, Zirconium‐, and Aluminium Alkoxides*

Benzoylacetone (bzac‐H) reacts with one equivalent of Al(OtBu)3 or Zr(OPr)4 to give the mono‐substituted compounds (bzac)Al(OtBu)2 (1b) and (bzac)Zr(OPr)3 (1a), while with one equivalent of Ti(OtBu)4 or Zr(OtBu)4 the bis‐substituted derivatives (bzac)2Ti(OtBu)2 (3c) and (bzac)2Zr(OtBu)2 (3d) are obtained. Upon heating in dibutyl ether, 1b disproportionates into (bzac)2Al(OtBu) (3b) and Al(OtBu)3. Thermal reaction of 1a, 3b, and 3c with Cr(CO)6 leads to metal complexes having a Cr(CO)3 moiety π‐bonded to the phenyl group of the benzoylacetonate ligand.
Alkoxygermanate(II), ‐stannate(II) und ‐plumbate(II) zweiwertiger Metall‐Ionen, II. Verbindungen des Formeltyps M2El2(OtBu)8
Authors: Veith Michael , Käfer Dieter , Koch Jürgen , May Peter , Stahl Lothar , Huch Volker
Published: July 2007

Alkoxygermanates(II), ‐stannates(II), and ‐plumbates(II) of Divalent Metal Ions, II[1]. – Compounds of the Formula M2El2(OtBu)8

By simple salt‐exchange processes the starting materials Na2El2(OtBu)6 (El = Ge, Sn, Pb) can be transformed to germanates, stannates and plumbates of divalent magnesium and divalent transition metals. Two types of compounds are formed in these reactions: MEl2(OtBu)6 [El = Ge, M = Mg (1A), Cr (1B), Mn (1C), Zn (1F); El = Pb, M = Mn (3C), M = Zn (3F)] and M2El2(OtBu)8 [El = Ge, M = Co (1d), Ni (1e); El = Sn, M = Mg (2a), Cr (2b), Mn (2c), Co (2d), Ni (2e); El = Pb, M = Co (3d)]. Single‐crystal X‐ray diffraction studies have been performed on 1C, 1d, 2a, 2b, 2c, 2d, and 2e, and the structures have been solved. In 1C the Mn atom occupies the center of an elongated O6 octahedron, the germanium(II) atoms displaying pyramidal coordination by three oxygen atoms. The central molecular cage can be described as two MnO3Ge trigonal bipyramids sharing the common central Mn atom and being wrapped by tert‐butyl groups linked to the oxygen atoms. The other compounds of the MEl2(OtBu)6 formula seem to be isostructural with the exception of 3F, which displays a 1H‐NMR spectrum which is not compatible with this structure. All X‐ray structures of the compounds M2El2(OtBu)8 show the same feature: to a central M2(OtBu)2 four‐membered ring are spirocyclically connected two M(OtBu)2El rings through the common metal atoms M. The structure is completed by the coordination of an exocyclic tert‐butoxy group to the terminal El atoms. The metal atoms M are therefore quasi tetrahedrally coordinated while the Ge and Sn atoms are in pyramidal threefold oxygen atom environments. All molecules display an El ⃛M ⃛M ⃛El one‐dimensional arrangement. From susceptibility measurements it is apparent, that in the compounds MEl2(OtBu)6 and M2El2(OtBu)8 the transition metal atoms are in high‐spin configurations, which is also supported by the UV spectra. Analysis of the structural data of the series 2a–2e reveal important contributions of the electronic environments of the transition metal atoms to the M ⃛M and M ⃛Sn distances. A qualitative MO description is used to explain these features. Again it has been shown that the, „geometrical softness”︁ of Ge(OtBu)3 and Pb(OtBu)3 is greater than of Sn(OtBu)3, as the former two can accomodate Cr2+ and Mn2+ in a sixfold coordination site by two units, while Sn(OtBu)3 coordinates Cr2+ and Mn2+ with only two alkoxy groups. When 1C and 2d are allowed to react with nonacarbonyldiiron Mn‐Ge2(OtBu)6 · 2 Fe(CO)4 (4) and Co2Sn2(OtBu)8 · 2 Fe(CO)4 (5), respectively, are formed. Compound 4 displays presumably five metal atoms in a linear arrangement while 5 has six metallic elements arranged in one dimension. The latter fact has been unambigously proved by an X‐ray structure determination.
Addition von Silylenen an Iminoborane
Authors: Paetzold Peter , Hahnfeld Detlef , Englert Ulli , Wojnowski Wieslaw , Dreczewski Boguslaw , Pawelec Zbigniew , Walz Leonhard
Published: July 2007

Addition of Silylenes to Iminoboranes[1]

Photolytically generated silylenes SiMe2 and SiMes2 are treated with iminoboranes XBNtBu [X = tBu, Me3Si(tBu)N, iPr2N: 1a–c]. The products from SiMe2 and 1a are the four‐and six‐membered rings [–B(tBu)=N(tBu)–SiMe2–SiMe2–] (3a) and [–B(tBu)N(tBu)B(tBu)magnified imageN(tBu)–SiMe2–SiMe2–] (4a), depending on the conditions of the photolysis. SiMe2 reacts with 1b to give the six‐membered ring [–BX=N(tBu)–SiMe2–BX=N(tBu)–SiMe2–] (4b). From SiMes2 and 1a,c the three‐membered rings [–BX=N(tBu)–SiMes2–] are formed (2a: space group Pbca; 2c: space group Pmagnified image1): SiMes2 reacts with 1b to yield the unexpected four‐membered BNSiN ring [magnified imageB(Mes)magnified imageN(tBu)–Si(Mes)(SiMe3)–N(tBu)magnified image] (5: space group Pmagnified image1).
Addition von Stannylenen an Iminoborane
Authors: Paetzold Peter , Hahnfeld Detlef , Englert Ulli
Published: July 2007

Addition of Stannylenes to Iminoboranes

Iminoboranes tBuB  NR (R = tBu, Mes: 1 a, b) undergo aminostannation by the diaminostannylene Sn[N(SiMe3)2]2 (2b) to give (Me3Si)2N‐B(tBu) = NR–Sn–N(SiMe3)2 (4a, b). The stannylene 4 b remains monomeric in the crystal (space group P21/n). The cyclic diaminostannylene [–Sn–N(tBu)–SiMe2‐N(tBu)–] (3 b), instead, simply adds the boranes 1 a, b across one of its Sn–N bonds to form the bicyclo[2.2.0]hexene‐type products 5a, b.
Umlagerungen von Bicyclo[3.2.1]oct‐2‐en‐6‐yl‐ und Benzobicyclo[3.2.1]octenyl‐Kationen
Authors: Kirmse Wolfgang , Mönch Dietmar
Published: July 2007

Rearrangement of Bicyclo[3.2.1]oct‐2‐en‐6‐yl and Benzobicyclo[3.2.1]octenyl Cations

The ketones 9, 27, and 51 were prepared by modified or novel routes. The analogous tosylhydrazones 10, 28, and 52 were photolyzed in 0.5 N NaOH (NaOD) to generate the carbocations 15, 34, and 53, respectively, by way of diazonium precursors. 2,3‐Unsaturation (15) and 2,3‐benzoanellation (34) affected the course of 4,6‐(4,5‐)hydride shifts, as elucidated by deuterium labeling. While the parent system 3 strongly prefers C‐5 over C‐6 (95:5) as the terminus of hydride shifts, 15 and 34 (55:45) approach the equivalence of C‐5 and C‐6 that is indicative of rapid Wagner‐Meerwein rearrangements or symmetrically bridged intermediates. This trend is attributed to flattening of the six‐membered ring in 15 and 24, as compared to the chair conformation of 3. On the other hand, predominant nucleophilic substitution at C‐6 is unaffected by 2,3‐unsaturation. We suggest that s̀ participation (kΔ) by alkyl groups is not sufficient to eliminate inverting displacement of nitrogen from the diazonium precursors by the solvent (ks). Equivalence of C‐5 and C‐6 toward external nucleophiles is achieved only by π participation, i.e. with the 3,4‐unsaturated and 3,4‐benzoanellated bicyclo[3.2.1]oct‐6‐yl systems (53).
Diastereo‐ and enantioselective synthesis of 1,2:5,6‐diepoxy‐4‐hydroxyalkyl carbamates. – regioselective ring opening and their transformation into doubly C‐branched deoxy sugar analogues
Authors: Peschke Bernd , Lüßmann Jörg , Hoppe Dieter , Dyrbusch Zzmichael
Published: July 2007

Enantiomerically enriched (Z)‐anti‐3,5‐dialkyl‐4‐hydroxy‐1,5‐alkadienyl N,N‐diisopropylcarbamates 12, readily obtained by the homoaldol approach, were oxidized with essentially complete diastereoselectivity to afford 1,2:5,6‐diepoxides 14 of D‐allo configuration. Conditions were worked out for the transformation of 14 into furanosides of types 19, 21, and 22 and for the selective nucleophilic introduction of carbon residues into the 6‐position to give chain‐elongated analogues 25. Altogether, a “brick‐box system” for the enantioselective construction of polystereogenic building blocks with a few synthetic steps from simple achiral starting materials [(E)‐2‐alkenyl carbamates of type 9 and 2‐alkyl‐2‐alkenals (11)] and nucleophiles, like Grignard reagents, is demonstrated.
Photoelectron Spectrum and Electronic Structure of Indigo
Authors: Rademacher Paul , Kowski Klaus
Published: July 2007

The He(I) photoelectron spectrum of indigo has been obtained by evaporating the compound at ca. 400°C. The ionization potentials are related to orbital energies or electronic states of the radical cation with the aid of semi‐empirical SCF‐MO calculations. A satisfactory interpretation of the spectrum up to 18 eV is obtained according to the HAM/3 method.
Enthalogenierung von Aminodihalogenboranen durch Na/K‐Legierung in Gegenwart von Naphthalin, Bis(trimethylsilyl)butadiin und 2,5‐Dimethyl‐2,4‐hexadien
Authors: Maringgele Walter , Knop Henning , Bromm Dietmar , Meller Anton , Dielkus Sven , Herbst‐Irmer Regine , Sheldrick George M.
Published: July 2007

Dehalogenation of Aminodihalogenoboranes by Na/K Alloy in the Presence of Naphthalene, Bis(trimethylsilyl)butadiyne, and 2,5‐Dimethyl‐2,4‐hexadiene

Reaction of naphthalene with Na/K alloy and [(2,6‐diisopropylphenyl)methylamino]difluoroborane (1) in 1,2‐dimethoxyethane yields the aminodimethoxyborane 2, the bis(amino)‐borane 3, the diborylethyne 4, and the diboryl oxide 5. By addition of a mixture of bis(trimethylsilyl)butadiyne or 2,5‐dimethyl‐2,4‐hexadiene with dichloro(diisopropylamino)borane to Na/K alloy in hexane the 2,4,5‐triborabicyclo‐[1.1.1]pentane 7 and the diboretane 8, resp., are obtained. 1H‐, 11B‐, 13C‐, 19F‐, 29Si‐NMR‐, IR, and MS data are given. For 2–4, 7 and 8 X‐ray structure analyses are performed.
Die Fluorsulfine XF2C(F)C  SO (X = F, Cl, Br), ihre Synthese und ungewöhnliche Zersetzungsart
Authors: Gradel Jan , Sundermeyer Wolfgang
Published: July 2007

The Fluorosulfines XF2C(F)C  SO (X = F, Cl, Br), Their Synthesis and Unusual Type of Decomposition

A new route for the synthesis of the sulfenyl chloride 3 opens an easy access to fluoro(trifluoromethyl)sulfine (6) by hydrolysis of 3, trapping 6 by Diels‐Alder reaction with anthracene, and thermolysis of the formed compound 8. By addition of the thioacetyl fluorides XF2C(F)C  S (X = Cl, Br) to anthracene compounds 9a, b are obtained, which could be oxidized to the sulfene adducts 12a, b as well as to the sulfine adducts 13a, b. Thermolysis of the latter yields the sulfines 17a, b, which are unstable at room temperature. A second approach to 17a involves oxidation of 1,3‐dithietane 11a to its S‐oxide 14a (e.g. via an S,S‐difluoro compound 15a) and subsequent thermolysis, but thermal decomposition predominates. An unusual decomposition has been observed for 17a, b which was hitherto unknown for sulfines.
Synthesis and Diels‐Alder Reactions of 1,2‐Dimethylene‐ and 1,2,9,10‐Tetramethylene[2.2]paracyclophane: New Routes to Bridge‐Anellated [2.2]Paracyclophanedienes
Authors: König Burkhard , Meijere Armin De
Published: July 2007

The title compounds 8 and 1 have been synthesized in three steps each from 1,2‐dibromo[2.2]paracyclophan‐1‐ene (2) and 1,2,9,10‐tetrabromo[2.2]paracyclophane‐1,9‐diene (4), respectively. Copper‐mediated coupling of vinyl bromides 2 and 4 with methyl‐ and phenylmagnesium bromide gives substituted [2.2]paracyclophanes 3‐CH3, 3‐Ph, 5‐CH3, and 5‐Ph in good yields. The high reactivity of the [2.2]paracyclophane‐1,2‐dimethylene moieties in 8 and 1 in Diels‐Alder reactions has been verified in cycloadditions with p‐benzoquinone to give 10 and 13 and with naphthalene 1,4‐endoxide to yield 12.
Mehrstufige reversible Redoxsysteme, LIX. Leitfähige Charge‐Transfer‐Komplexe von 2,5‐Bis(cyanimino)‐2,5‐dihydrothieno[3,2‐b]thiophenen mit organischen Donoren
Authors: Günther Erhard , Hünig Siegfried , Schütz Jost‐Ulrich Von , Langohr Uwe , Rieder Harald , Söderholm Svante , Werner Hans‐Peter , Peters Karl , Schnering Hans Georg Von , Lindner Hans Jörg
Published: July 2007

Conducting Charge‐Transfer Complexes of 2,5‐Bis(cyanoimino)‐2,5‐dihydrothieno[3,2‐b]thiophenes with Organic Donors

From the title compound 4 and several donors 13 charge‐transfer (CT) complexes have been obtained. Most of them show powder conductivities of 0.01–2.0 Scm−1. The crystal structure of 4d/TTF (20 Scm−1) reveals segregated stacks of donor and acceptor molecules in a novel stacking pattern. The structure of 4d/TMTSF consists of mixed stacks (insulator), however a second phase (no structure available) exhibits very high conductivity (200 Scm−1).
Lanthanoiden‐Komplexe, I Solvensfreie Alkoxid‐Komplexe des Neodyms und Dysprosiums. Kristall‐ und Molekülstruktur von trans‐Bis(acetonitril)tris(tri‐tert‐butylmethoxy)neodym
Authors: Herrmann Wolfgang A. , Anwander Reiner , Kleine Matthias , Scherer Wolfgang
Published: July 2007

Complexes of the Lanthanides, I. – Solvent‐Free Alkoxide Complexes of Neodymium and Dysprosium. Crystal and Molecular Structure of trans‐Bis(acetonitrile)tris(tri‐tert‐butylmethoxy)neodymium The first lanthanide complex 3a is obtained from the sterically demanding silanol (tC4H9)3SiOH (, „silox”︁, 1a) and Nd‐[N{Si(CH3)3}2]3 (2a). Similarly, the bulky alcohols, „tritox‐H”︁, tri‐tert‐butylmethanol (1b), and, „ditox‐H”︁, di‐tert‐butylmethanol (1c), react with 2a to give the corresponding alkoxide complexes Nd(tritox)3 (3b) and [Nd(ditox)3]2 (3c), respectively. Under the same conditions Dy[N{Si(CH3)3}2]3 (2b) yields the homoleptic ditox derivative 6. The new complexes are all very soluble in aliphatic hydrocarbons. They show a very different thermal stability as, for example, expressed in their sublimation behaviour.
Neue Synthesen und Reaktionen von Phosphetaniumsalzen mit planarem Gerüst
Authors: Brauer David J. , Ciccu Antonella J. , Heßler Gisbert , Stelzer Othmar
Published: July 2007

Novel Syntheses and Reactions of Phosphetanium Salts with a Planar magnified image Skeleton

Cleavage of the P–Si bond of silylphosphanes R2P‐SiMe3 (R = iPr, tBu, 2,4,6‐Me3C6H2) with excess 1,3‐dihalogenpropanes X–[CH2]3–X (X = Br, I) affords phosphetanium salts magnified image (3) in good yields. These strained four‐membered ring systems are also obtained by alkylation of secondary phosphanes R2PH with X–[CH2]3–X followed by deprotonation of the intermediate phosphonium salts [R2P(H)—[CH2]3–X]+ X‐ (R e.g. tBu; X = Br, 7b). Silylphosphanes and secondary phosphanes with less bulky substituents preferably form open‐chain phosphonium salts with [CH2]3–X or allyl substituents in these reactions. X‐ray structural analysis of magnified image (3h) reveals planar geometries for the PC3 skeletons of the cations. The reactivity of 3b towards different types of nucleophiles [F‐, NH2‐, OH‐, OR‐, Fe(CO)2Cp‐, NaN(SiMe3)2, RR′PLi] has been studied. Reaction with CsF or NaNH2, leads to a stable monofluoro or monoamino phosphorane, respectively, with cyclic four‐membered PC3 skeletons. In all other cases opening of the phosphetanium ring system occurs leading to derivatives with R2P—[CH2]3 terminal groups. Bidentate and polydentate ligands, e.g. 19–25, with bulky substituents in terminal position have been synthesized in high yields by cleavage of 3b with mono‐ and bifunctional lithium phosphides. By deprotonation of 3b with MeLi the cyclic ylide 14 is formed. Treatment with acetone or benzaldehyde leads to the unsaturated open‐chain phosphane oxides 15a or 15b in a Wittig‐type reaction.
Cycloadditionsreaktionen von Phosphenium‐Metallkomplexen, 2. Cyclisierte Phosphiniden(metallo)phosphorane durch Addition von, „Methylphosphiniden”︁ an Phosphenium‐ und Arsenium‐Wolframkomplexe
Authors: Malisch Wolfgang , Hindahl Kathrin , Schemm Rudolf
Published: July 2007

Cycloaddition Reactions with Phosphenium Metal Complexes, 2. – Cyclized Phosphinidene(metallo)phosphoranes by Addition of “Methylphosphinidene” to Phosphenium and Arsenium Tungsten Complexes

Cyclized phosphinidene(metallo)phosphoranesmagnified image(3a, b, 5) are obtained from Cp(OC)2W = ER2(E = P, As; R =tBu,oTol)(1a, b, 4) and (MeP)5(2). Treatment of3awith CH3I yields the cationic η2‐diphosphane complexmagnified image(6). The reaction of3bwith elemental sulfur and selenium leads to the four‐membered metallacyclesmagnified image(X = S, Se) (7a, b).
Asymmetrische Katalyse, 67. Diastereoselektive Hydrierung der Folsäure mit optisch aktiven Rhodium(I)‐Diphosphan‐Komplexen
Authors: Brunner Henri , Huber Christian
Published: July 2007

Asymmetric Catalysis, 67[1]. – Diastereoselective Hydrogenation of Folic Acid with Optically Active Rhodium(I)‐Diphosphane Complexes

With immobilized rhodium(I)‐diphosphane catalysts supported on silica gel, the C = N bonds of the pyrazine ring of folic acid (1) are reduced with hydrogen in aqueous solution to give 5,6,7,8‐tetrahydrofolic acid. A mixture of the two diastereomers 2a and 3a is obtained with (6S)‐ and (6R)‐configuration, respectively, at the newly formed asymmetric center in the pterine system and (S)‐configuration in the L‐glutamic acid moiety. The unstable hydrogenation products are derivatized with (‐)‐menthyl chloroformate. An improved HPLC procedure for the analysis of the products has been developed. By using optically active chelate phosphanes as cocatalysts together with [Rh(cod)Cl]2, a diastereomeric excess of up to 24% of the natural isomer 2a with (6S,S)‐configuration is attained in the heterogeneous hydrogenation of folic acid.
Kleine Ringe, 74. Hexa‐tert‐butyl‐3,3′‐bicyclopropenyl
Authors: Maier Günther , Schick Andreas , Bauer Ines , Boese Roland , Nussbaumer Michael
Published: July 2007

Small Rings, 74[1]. ‐ Hexa‐tert‐butyl‐3,3′‐bicyclopropenyl

Title compound 3 can be prepared by reductive coupling of tri‐tert‐butylcyclopropenylium tetrafluoroborate (4a) with lithium. Upon treatment with AgBF4 3 does not undergo valence isomerization to the Dewar form of hexa‐tert‐butylbenzene (2) but is reoxidized under backformation of substrate 4a. The photochemical behavior of 6 is also unusual: Irradiation at room temperature results in gas evolution. However, instead of 7, the s̀‐diketone 5 is isolated. Monoketone 7 is only formed if 6 is irradiated in an organic matrix at ‐196°C.