bluuebunny/crossref_metadata_2025_split huggingface dataset:
Gas‐Phase Thermolysis of Pyrazolines, 2[1]. Electronic Structure and Gas‐Phase Thermolysis of 4,5‐Dihydro‐3H‐pyrazoles Studied by Photoelectron Spectroscopy, Semiempirical Quantum‐Chemical Calculations, and Flash Vacuum Pyrolysis
Authors: Kindermann Markus Karl , Kowski Klaus , Muchall Heidi M. , Rademacher Paul 
Published: July 2007

AbstractThe PE spectra of the 4,5‐dihydro‐3H‐pyrazoles 1, 2, of 2,5‐dihydro‐1,3,4‐oxadiazole 3, and 2,5‐dihydro‐1,3,4‐thiadiazole 4 have been recorded. Based on HAM/3, MNDO, AM1, and PM3 calculations, the ionization potentials have been assigned to molecular orbitals. The gas‐phase thermolyses of 1–4 have been studied by PE‐controlled gas analysis. Extrusion of molecular nitrogen leads to reactive species which cyclize to three‐membered rings of different stability. At higher temperatures and in flash vacuum pyrolysis, consecutive reactions may lead to smaller acyclic molecules. The cyclo‐propanol 7, obtained by denitrogenation of 2, is thermally rather stable. Its PE spectrum has been recorded and analyzed.
Synthese optisch aktiver 2‐Siloxycyclopropancarbonsäureester durch asymmetrische Katalyse, II[1]. Einfluß der Silylenolether‐Struktur auf die enantioselektive Cyclopropanierung mit Diazoessigsäure‐methylester
Authors: Dammast Franziska , Reißig Hans‐Ulrich 
Published: July 2007

Synthesis of Optically Active Siloxycyclopropanes by Asymmetric Catalysis, II[1]. – Influence of the Silyl Enol Ether Structure on the Enantioselective Cyclopropanation with Methyl DiazoacetateOn the basis of reactions of (Z)‐1‐phenyl‐1‐(trimethylsiloxy)‐1‐propene (1a) with methyl diazoacetate (2) in the presence of different chiral (Schiff base) copper catalysts 4‐Cu we extended our study to the silyl enol ethers 1b–1j. The highest enantiomeric excesses were obtained in most cases with catalyst 4b‐Cu. Whereas cyclopropanations of 1‐aryl‐ and 1‐alkenyl‐substituted silyl enol ethers 1b–1h gave moderate to good enantioselectivities (up to 80%ee), alkyl‐substituted olefins 1i and 1j provided less satisfactory results. By deprotonation and alkylation of 3c, 3h, and 3i it could be established that for these cyclopropanes the predominating absolute configuration of cis‐ and trans‐cyclopropanes is equal at C‐1, but consequently opposite at C‐2. The influence of the silyl enol ether structure on the enantioselectivities achieved is briefly discussed.
Functionalized, 1,1‐Ethenedithiolates as Ligands, III. Palladium(II) and Platinum(II) Complexes with Ferrocenyl‐Substituted 1,1‐Ethenedithiolate Ligands. Crystal Structure Analyses of cis‐(Ph3P)2M[S2CCHC(O)‐(η5‐C5H4)Fe(η5‐C5H5)] (M = Pd, Pt)
Authors: Buchweitz Jörg , Gompper Rudolf , Polborn Kurt , Sailer Maria‐Theresia , Robl Christian , Weigand Wolfgang 
Published: July 2007

AbstractThe ferrocenyl‐substituted mono‐ (3) and 1,1′‐bis‐dithiocarboxylic acids (4) have been prepared. These acids react with L2MCl2 (M = Pd, Pt; L = PEt3, PPh3, and 1/2 dppe) in the presence of sodium acetate to give the cis heterodi‐ and heterotrimetallic complexes cis‐L2M[S2CCHC(O)–(η5‐C5H4)Fe(η5‐C5H5)] (5a: M = Pd, L = PPh3; 5b: M = Pt, L = PPh3; 5c: M = Pt, L = 1/2 dppe) and [cis‐L2MS2C = CHC(O)‐(η5C5H4)]2Fe (6a: M = Pd, L = PPh3; 6b: M = Pt, L = PEt3; 6c: M = Pt, L = PPh3; 6d: M = Pt, L = 1/2 dppe). The structures of 5a and 5b have been determined by single‐crystal X‐ray diffraction.
Zur Chemie der Galliumverbindungen, II. Darstellung und Struktur von Bis(2,2,6,6‐tetramethylpiperidino)‐[tris(trimethylsilyl)silyl]gallium — ein erstes Beispiel für ein monomeres Bis(amino)gallan mit Gallium‐Silicium‐Bindung
Authors: Frey Ronald , Linti Gerald , Polborn Kurt 
Published: July 2007

On the Chemistry of Gallium Compounds, II[1]. — Preparation and Structure of Bis(2,2,6,6‐tetramethylpiperidino)‐[tris(trimethylsilyl)silyl]gallium — ein First Example for a Monomeric Bis(amino)gallane with Gallium‐Silicon BondThe title compound tmp2GaSi(SiMe3)3 (4) (tmp = 2,2,6,6‐tetramethylpiperidino) was prepared by the reaction of (Me3Si)3SiLi · 3 THF (2) with tmp2GaCl (3). The NMR data (1H, 13C, 29Si) and the crystal structure of 4 are discussed. It contains a trigonal planar‐coordinated gallium atom with long Ga‐N and GaSi bonds of 191 and 247 pm, respectively. This compound is the first fully characterized monomeric gallium bis(amide) and the second structurally investigated compound with a gallium‐silicon bond.
Synthese dienophiler und enophiler Phthalocyanine
Authors: Feucht Carola , Linßen Torsten , Hanack Michael 
Published: July 2007

Synthesis of Dienophilic and Enophilic PhthalocyaninesFrom 1,2,3,4‐tetrahydro‐2,3‐dimethylen‐1,4‐epoxynaphthalene‐6,7‐dicarbonitrile (2) or the corresponding 1,3‐diimino‐1,3‐dihydroisoindole 3 the hexadecahydro‐octamethylenetetraepoxynaphthalocyanine 4 as well as the nickel and the iron complexes 5 and 6 containing enophilic side groups have been synthesized. From 1,4‐dihydro‐1,4‐epoxynaphthalene‐6,7‐dicarbonitrile (8) and its corresponding 1,3‐diimino‐1,3‐dihydroisonindole 9 the octahydro‐tetraepoxynaphthalocyanines 10, 11, and 12, respectively, which contain dienophilic substituents, are obtained. 11 reacts with 2,3‐dimethylbutadiene to form the adduct 13.
Benzoanellated Centropolyquinanes, 15. Benzoanellated Fenestranes with [5.5.5], [5.5.5.6], and [5.5.5.5] Frameworks: The Route from 1,3‐Indandione to Fenestrindan
Authors: Kuck Dietmar 
Published: July 2007

AbstractThe synthesis and spectroscopic characterization of several benzoanellated [5.5.5]‐, [5.5.5.6]‐, and [5.5.5.5]fenestranes, including the parent difuso‐centrotriindan 7, the parent tetrafuso‐centrotetraindan 8 (“fenestrindan”) as well as the tribenzo[5.5.5.6]‐ and tribenzo[5.5.5.5]fenestranes 27 and 35, are described and discussed in full experimental detail. The highly efficient twofold cyclodehydration of 2,2‐dibenzyl‐1,3‐indandiol 15 and the related spiro‐condensed 1,3‐indandiols 23 and 29 is the keystep of the synthetic strategy. The new synthetic variant involving the one‐pot cyclodehydration/deketalization of the dispiro‐ketal diol 29 is particularly convenient. In the case of 7, an alternative Lewis acid‐catalyzed double cyclization has been developed. Stereochemical aspects of the 1,3‐indandiols and the key tribenzo[5.5.5.6]fenestranes 24 and 25 are discussed in detail.
Tris(perfluororganochalkogenyl)methyl‐Verbindungen: Synthesen, Strukturen und Eigenschaften
Authors: Boese Roland , Haas Alois , Lieb Max , Roeske Ulrich 
Published: July 2007

Tris(perfluoroorganochalkogenyl)methyl Compounds: Synthesis, Structures, and PropertiesReaction of (CF3S)2CHC(OC2H5)3 with CF3SCl or CF3SeCl in the presence of NaH in ether provides X(CF3S)2CC(O)OC2H5 (1a, b: X = CF3S, CF3Se). These compounds react with NH3 to form (CF3S)2CHC(O)NH2 (2b) which is also obtained from (CF3S)2CHC(O)OC2H5 and NH3. Dehydration of the amide 2b yields (CF3S)2CHCN (3b), which reacts with NaH and then with CF3SX (X = Cl, SCF3) or with RfCl (Rf = CF3Se, C6F5S) to give Rf (CF3S)2CCN [Rf = CF3S (3c), CF3Se (3d), C6F5S (3e)]. 3c is also obtained from (CF3S)3CBr and AgCN. Hydrolysis of 3c with conc. H2SO4 leads almost quantitatively to (CF3S)3CC(O)NH2 (2c), which on treatment with COCl2 gives only 3c and not the corresponding isocyanate. If phosgene is replaced by oxalyl chloride and treated with 2c in a 1:1 molar ratio, (CF3S)3CC(O)NCO (4a) is formed. The urea derivative (CF3S)3CC(O)NHC(O)NHC(O)C(SCF3)3 (4b) is obtained either by using a 2:1 molar ratio of 2c and [C(O)Cl]2 or from 2c and 4a. Attempts to substitute (CF3S)2CHCO2H ‐ after treatment with NaH in ether ‐ with CF3SCl provides low yields of 2,4‐bis[bis(trifluoromethylsulfanyl)methylene]‐1,3‐dithietane (5). X‐ray structure analyses are performed for (CF3S)3CCN (3c) and the 1,3‐dithietane 5.
Trimethylsilylierte 1,4‐Diborinane und 1,3‐Diborolane ‐ Bildung, Isomeren‐Trennung und Charakterisierung
Authors: Köster Roland , Seidel Günter , Lutz Frank , Krüger Carl , Kehr Gerald , Wrackmeyer Bernd 
Published: July 2007

Trimethylsilylated 1,4‐Diborinanes and 1,3‐Diborolanes – Formation, Isomer Separation, and CharacterisationMe3SiCCH (A) reacts with excess (Et2BH)2 via the compounds 1, 1′ and 2, 2′ to yield a mixture of four regio‐ and stereoisomeric 1,4‐diethyl‐2,5(6)‐bis(trimethylsilyl)‐1,4‐diborinanes (3a–d) and minor amounts of 1,3‐diethyl‐2‐methyltrans‐2,5‐bis(trimethylsilyl)‐1,3‐diborolane (4a). The 2,5‐ee‐(Me3Si)2 compound 3d is isolated as the adduct 3d(Pic)2 (X‐ray structure analysis), from which pure 3d is obtained with Et2O‐BF3. 3d and Me3P form equilibria of the 1:1 and 1:2 addition compounds 3d(Me3P)n (n = 1,2) at room temperature. Me3SiCCMe (B) reacts with (Et2BH)2 via 5 to give 6–10, and Me3SiCCSiMe3 (C) reacts with (Et2BH)2 to form the ring compounds 12 and 13 via the presumably threo/erythro mixture of 11a and b.
Synthesis and Structure of N‐Silylated Anilines
Authors: Mitzel Norbert W. , Angermaier Klaus , Schmidbaur Hubert 
Published: July 2007

AbstractThe new N‐(arylsilyl)anilines 1–5 have been obtained by the reaction of aryl(halo)silanes with the corresponding anilines in the presence of the auxiliary base triethylamine. The benzene parts of the anilines have been chosen such that their fluoro, methyl, and methoxy substituents exert different electronic effects. The molecular structures of the monosilylated anilines 3 and 4 have been determined by single‐crystal X‐ray diffraction analysis. The coordination geometry of the nitrogen atoms have been found to be planar. Heteronuclear NMR spectra (1H, 13C, 15N, 29Si) have been recorded and the structural results correlated with the one‐bond coupling constant 1J(29Si15N).
Derivate des Imidazols, IX. Stabilisierung von Selendiiodid durch Komplexbildung
Authors: Kuhn Norbert , Kratz Thomas , Henkel Gerald 
Published: July 2007

Imidazole Derivatives, IX. — Stabilisation of Selenium Diiodide by ComplexationHerrn Professor Helmut Werner zum 60. Geburtstag gewidmet.
Stable selenium diiodide complexes 2 are obtained by the reaction of the 2‐selenoxoimidazolines 1 with iodine. An X‐ray structure analysis of 2c reveals its monomeric nature. In the trigonal bipyramid, the iodo substituents are situated in axial positions forming elongated iodine bonds [Se–I(1) 2.854(1), SeI(2) 2.768(1) Å; I(1)SeI(2) 175.4(0)°].
Zur Thermolyse von Amin—arachno‐Nonaboran
Authors: Meyer Franc , Englert Ulli , Paetzold Peter 
Published: July 2007

On the Thermolysis of Amine‐arachno‐NonaboraneTwo molecules of diethylamine‐arachno‐nonaborane, B9H13‐(NHEt2), undergo a condensation at 140°C to give diethylamine‐conjuncto‐bis[6′,5′:5,6]decaborane, B18H20(NHEt2) (4). The deprotonation of 4 yields the anion [B18H19(NHEt2)]‐which can be crystallized with the cation [NEt3(CH2Ph)]+ (space group P1).
Cycloadditionen von 2H‐Benzo[b]thiet und Verbindungen mit kumulierten Doppelbindungen
Authors: Gröschl Dieter , Niedermann Hans‐Peter , Meier Herbert 
Published: July 2007

Cycloaddition Reactions of 2H‐Benzo[b]thiete and Compounds with Cumulated Double Bondso‐Thiobenzoquinone methide (2), generated by thermal ring opening of 2H‐benzo[b]thiete (1), reacts with allene 3, ketene imine 7, the carbodiimides 9a‐c, and the N‐sulfinylamines 11a‐c in highly specific [8π + 2π] cycloaddition processes to form novel types of heterocyclic systems 4, 8, 10a‐c, and 12a‐c with exocyclic double bonds. The 1:1 adduct 4 can add a further molecule of allene to yield the spiro compounds 5 and 6.
Zur oxidativen Dimerisierung von CH‐Säuren
Authors: Peek Reinhold , Streukens Marlies , Thomas Hans Günter , Vanderfuhr AndrÉ , Wellen Ulrich 
Published: July 2007

Oxidative Dimerization of CH AcidsAnodic oxidation of alkyl‐ (1) and acylmalonic acid esters (7) yields the dehydromiers 4 and 8, respectively. Preparative electrolyses are performed in acetonitrile in the presence of a base to generate the carbanion corresponding to the CH acid. The carbanions are oxidized to the radicals which dimerise on the electrode surface. The yields of the preparative electrolyses and the formation of the dehydrodimers 4 and 8 are discussed in terms of the CH acidity and enolization of starting materials.
Übergangsmetall‐katalysierte Reaktionen von ungesättigten α‐Diazo‐α‐(trimethylsilyl)essigestern mit Carbonylverbindungen
Authors: Alt Mechthild , Maas Gerhard 
Published: July 2007

Transition Metal Catalyzed Reactions of Unsaturated α‐Diazo‐α‐(trimethylsilyl)acetates with Carbonyl CompoundsSome reactions of unsaturated α‐diazo‐α‐(trimethylsilyl)acetates with aldehydes or acetone under the catalytic action of rhodium(II) perfluorobutyrate or copper(I) triflate have been investigated. Thus, the allylic ester 6a affords 1,3‐dioxolan‐4‐ones 8 under Rh(II) catalysis; the Cu‐catalyzed reaction yields 8, oxirane 9, and the 3‐oxabicyclo[3.1.0]hexane 10. The propargylic ester 6b does not react in a clear fashion with benzaldehyde, 1,3‐Dioxolanes result from the homoallylic ester 6c and aldehydes, but enol ether 14 from 6c and acetone.
Triphenanthro‐anellierte [18]Annulene mit Alkoxy‐Seitenketten — Eine neue Klasse discotischer Flüssigkristalle
Authors: Kretzschmann Holger , Müller Klaus , Kolshorn Heinz , Schollmeyer Dieter , Meier Herbert 
Published: July 2007

AbstractTriphenanthro‐Anellated [18]Annulenes with Alkoxy Side Chains ‐ A Novel Class of Discotic Liquid CrystalsTwo different types 6 and 16 of [18]annulenes condensed with phenanthrene systems were prepared by cyclocondensation reactions (Schemes 2 and 3). The central 18‐membered rings do not show a macrocyclic diamagnetic ring current. Conformational analyses and X‐ray analyses in the solid state reveal non‐planar structures in which aromatic “islands” are connected by (E)‐configurated olefinic bridges. The introduction of long alkoxy side chains yields a new class of discotic liquid crystals; either ND or hexagonal columnar phases are generated, which were characterized by DSC, microscopy with polarized light, and small‐angle scanning X‐ray.
How Electrophilic are Ferrocenylmethyl Cations? Kinetics of their Reactions with π Nucleophiles and Hydride Donors
Authors: Mayr Herbert , Rau Doris 
Published: July 2007

AbstractSecond‐order rate constants for the reactions of the ferrocenylmethylium ions 2a—e with silyl enol ethers, allylsilanes, allylstannanes, and hydride donors have been determined photometrically and conductometrically in dichloromethane. The ferrocenylmethylium ions 2a—d (fc‐CHR+, R = H, Me, Ph, An) are slightly stronger electrophiles than the tropylium ion, and their electrophilic reactivities depend only slightly on the nature of R. The bis(ferrocenyl)methylium ion 2e is a considerably weaker electrophile, comparable to the tricarbonyl(cyclohexadienyl)iron cation.
Palladium‐Catalysed Multiple Coupling Reactions of β‐Bromostyrene with Norbornene and Dicyclopentadiene
Authors: Albrecht Karsten , Meijere Armin De 
Published: July 2007

Abstract(E)‐β‐Bromostyrene [(E)‐2] reacts with norbornene (1a) or dicyclopentadiene (1b) in the presence of Pd(OAc)2, K2CO3, and nBu4NBr in DMF to yield a mixture of the 2:1 coupling products 4 and 5, while (Z)‐β‐bromostyrene [(Z)‐2] gives exclusively 5. Under analogous conditions, (Z)‐3‐iodoacrylic acid (6) reacts with norbornene (1a) to give the diene 11 with an exo, exo‐2,3‐disubstituted norbornane skeleton.
Synthese und Struktur von Cobalt(III)‐Komplexen mit doppelt deprotoniertem Anhydroerythrit, Methyα‐D‐mannopyranosid und Methyl‐β‐D‐galactopyranosid
Authors: Burger Joachim , Klüfers Peter 
Published: July 2007

AbstractPolyol Metal Complexes, XII[1]. — Synthesis and Structure of Cobalt(III) Complexes with Doubly Deprotonated Anhydroerythritol, Methyl α‐DMannopyranoside, and Methyl α‐DGalactopyranosideThe polyols anhydroerythritol (AnEryt), methyl α‐D‐mannopyranoside (Me‐α‐D‐Manp), and methyl α‐D‐galactopyrano‐side (Me‐α‐DGalp) are deprotonated twice to form the cobalt(III) complexes [(en)2Co(AnErytH‐2)]I (1), δ‐[(en)2‐ Co(Me‐α‐DManp3,4H‐2)]ClO4 · NaClO4 · 2H2O (2), and δ‐[(en)2Co(Me‐α‐DGalp2,3H‐2)]ClO4·H2O (3), resp., in aqueous, alkaline solutions of trans‐[(en)2CoCl2]Cl. The crystal structures of 1–3 have been determined by X‐ray diffraction.
Synthesis, X‐Ray Crystal Structure and Magnetic Characterization of the First “Ni3S4N3” Nickel Thiolate Cluster
Authors: Berkessel Albrecht , Bats Jan W. , Hüber Martina , Haase Wolfgang , Neumann Thomas , Seidel Lutz 
Published: July 2007

AbstractThe tridentate N,O,S‐ligand (RS)‐2‐[(2‐mercapto‐1‐methylamino)ethyl]phenol (rac‐1) was prepared from ortho‐hydroxy‐chloroacetophenone in three steps. When this ligand was treated with nickel(II) acetate, the novel “Ni3S4N3” cluster rac‐3 was obtained. The X‐ray crystal structure of rac‐3 unambiguously revealed the pseudo‐C3 symmetric structure of this novel nickel cluster, which is made up by three nickel ions, one sulfide sulfur atom, and three homochiral ligand molecules, each contributing one thiolate sulfur atom and one amine nitrogen atom to the ligation of the metal ions. According to NMR‐spectroscopic results, this highly symmetric structure is maintained in solution. The magnetic studies revealed diamagnetic behavior in the solid state, although antiferromagnetic interaction of the metal centers cannot absolutely be excluded.
Ion Pair Charge‐Transfer Complexes of Dithiolene Metalates with Diquaternary 2,2′‐Biimidazoles
Authors: Lemke Matthias , Knoch Falk , Kisch Horst , Salbeck Josef 
Published: July 2007

AbstractCycloalkylated biimidazolium dications (A2+) of reduction potentials from ‐0.4 to ‐1.4 V form ion pair charge‐transfer complexes {A2+ [M(mnt)2]2−} with dithiolene metalates, M = Zn, Ni, Pd, Pt, mnt2− = maleonitrile‐2,3‐dithiolate. X‐ray analyses of {P2BBIm2+[Ni(mnt)2]2−} [P2BBIm2+ = 1,1′,3,3′‐bis(propane‐1,3‐diyl)bibenzimidazolium] and {B2Blm2+ [Pd(mnt)2]2−} [B2BIm2+ = 1,1′,3,3′‐bis(butane‐1,4‐diyl)biimidazolium] reveal that the solid‐state structure is largely determined by the geometry of the acceptor. When the latter is strongly twisted, the usually observed mixed donor‐acceptor columns are modified to a chain‐like arrangement. In the case of the bibenzimidazolium dication P2BBIm2+ the otherwise planar [Ni(mnt)2]2− becomes tetrahedrally distorted. By the application of the Hush model a reorganization energy of about 67 kJ/mol is estimated for the thermal electron transfer from [M(mnt)2]2− to A2+ when M = Ni, Pd, Pt, but considerable deviations from this model are observed when M = Zn. Irradiation of the free biimidazolium acceptors in the presence of EDTA affords the strongly reducing radical cations which reduce water to hydrogen in the presence of colloidal platinum. Attempts to sensitize this reaction by irradiating into the charge‐transfer band of {A2+ [M(mnt)2]2−} have failed until now. The molar absorptivity of one biimidazolium radical cation is measured by spectroelectrochemistry.
Erste strukturelle Charakterisierung eines 3‐Silaoxetans und 3‐Silathietans im Kristall und in Lösung
Authors: Strohmann Carsten 
Published: July 2007

First Structural Characterisation of a 3‐Silaoxetane and a 3‐Silathietane in the Crystal and in SolutionThe 3‐silaoxetane 3,3‐dimethyl‐2,2,4,4‐tetraphenyl‐1‐oxa‐3‐silacyclobutane (1) and the 3‐silathietane 3,3‐dimethyl‐2,2,4,4‐tetraphenyl‐1‐sila‐3‐thiacyclobutane (2) were synthesized and studied in the solid state and in solution. The crystal structures of 1 and 2 were investigated by X‐ray diffraction. Furthermore, 1 and 2 were characterized by solid‐state NMR spectroscopy (13C and 29Si CP/MAS). The cyclobutane ring of 1 is planar with a C‐Si‐C angle of 75.07(9)° and a C‐O‐C angle of 105.3(2)°. 2 crystallizes with a non‐planar cyclobutane ring with a C‐Si‐C angle of 89.00(11)° and a C‐S‐C angle of 93.25(11)°. The Si‐O distance of 241.5(3) pm for 1 and the Si‐S distance of 263.9(3) pm for 2 are shorter than the sum of the van der Waals radii of these atoms. The results obtained by X‐ray diffraction are consistent with those from solid state 13C‐NMR spectroscopy for 1 and 2. Different 29Si‐NMR spectra in solution and the solid state indicate unusual electronic or steric effects around the silicon atom of 2 in the solid.
Reactions of Diazo Compounds and Chiral Rhenium Alkylidene Complexes of the Formula [(η5‐C5H5)Re(NO)(PPh3)(CHR)]+ PF A Versatile and Highly Stereoselective Route to Alkene Complexes
Authors: Wang Van , Gladysz John A. 
Published: July 2007

AbstractThe methylidene complex [(η5‐C5H5)Re(NO)(PPh3)(CH2)]+ PF or the ReCD2 analog react with diazo compounds N2CHR [R  H, Si(CH3)3, COPh, CO2C2H5] in CH2Cl2 at −80°C to give alkene complexes [(η5‐C5H5)Re(NO)(PPh3)(η2‐H2CCHR)]+ PF or D2CCHR analogs. The two ReC geometric isomers of benzylidene complex [(η5‐C5H5)Re‐(NO)(PPh3)(CHPh)]+ PF and CH2N2 react to give opposite configurational diastereomers of styrene complex [(η5‐C5H5)Re(NO)(PPh3)(η2‐H2CCHPh)]+ PF. Stereochemical features of these reactions are analyzed in detail, and are interpreted in terms of models involving (a) attack of the diazo compound upon the ReC face opposite to the bulky PPh3 ligand, (b) an antiperiplanar disposition of the ReC and CN2 bonds in the transition state, utilizing the diazo carbon face that minimizes interactions of the substitutent (R) and cyclopentadienyl ligand, and (c) N2 loss from the resulting intermediate [(η5‐C5H5)Re(NO)(PPh3)(CHR′CHRN2)]+ PF via a conformer with antiperiplanar PReCHR′C and ReCHR′CHRN linkages, with anchimeric assistance of the rhenium fragment d orbital HOMO from the backside.
Tripodal Amides Containing a Totally Silicon‐Based Ligand Framework
Authors: Schubart Martin , Findeis Bernd , Gade Lutz H. , Li Wan‐Sheung , McPartlin Mary 
Published: July 2007

AbstractA novel type of tripodal amido ligand with a totally siliconbased (trisilylsilane‐derived) ligand framework has been synthesized and coordinated to tetravalent titanium and zirconium. The key compound in the ligand synthesis is the chlorosilane H3CSi{Si(CH3)2CI}3 (2) which upon condensation with a range of primary amines R‐NH2 (R = aryl, alkyl) yields the amino‐functionalized ligand precursors H3CSi{Si(CH3)2NHR}3 (3a–e). Their corresponding trilithium salts have been found to be the appropriate amide transfer reagents in the subsequent syntheses of the transition metal complexes. Single‐crystal X‐ray structure analyses of the trilithium triamide H3CSi{Si(CH3)2N(Li)tBu}3 (4a) and the Ti complex H3CSi{Si(CH3)2N(p‐Tol)}3TiBr (5b) have established their respective adamantane‐ and [2.2.2]bicyclooctane‐related cage structures.
Carbohydratocarbene Complexes of Manganese and Rhenium
Authors: Fischer Helmut , Schleu Joachim , Roth Gerhard 
Published: July 2007

AbstractThe cationic carbyne complexes [Cp(CO)2MCR]+ [BX4]− [M = Mn, X = F: R = Ph (1), Tol (2); M = Re, X = 3,5‐C6H2(CF3)2: R = Ph (3)] add the anion of monodeprotonated protected mannofuranose (4a), glucofuranose (4b), and fructopyranose (4c) to the carbyne carbon atom to form the carbohydratocarbene complexes 5a–c, 6a, b, and 7a. With 5b, 5c, and 6b the addition proceeds with retention of configuration at the anomeric center. Due to inversion of configuration in the deprotonation step the complexes 5a, 6a, and 7a are obtained as β‐glycosides. The carbene ligand is oxidatively cleaved from the metal by trimethylamine N‐oxide or air. Cleavage of the C(carbene)O bond with reformation of the cation of the carbyne complex 2 is achieved by reaction of 6a with BCl3. Photolysis of [Cp(CO)2MnC(Ph)OEt] in the presence of L affords the carbene complexes [Cp(CO)(L)MnC(Ph)OEt] [L = P(OMe)3 (11), P(Tol)3 (12)]. Ethoxide abstraction from 11 and 12 by BF3 gives the chiral cationic carbyne complexes [Cp(CO)(L)MnCPh]+[EF4]− (13, 14) which add 4a to form the corresponding mannofura‐nosylcarbene complexes (15, 16). When 0.5 equivalents of 4a are employed in the reaction with 13, 14 the ratio of diastereomers is 3:2, both for 15 and 16. Complex 11 was characterized by an X‐ray structural analysis.