bluuebunny/crossref_metadata_2025_split huggingface dataset:
Diimidokomplexe [M(NR)2(PMe3)2(L)] des vierwertigen Molybdäns und Wolframs: Struktur, Moleküldynamik und Aktivierung π‐acider Liganden
Authors: Radius Udo , Sundermeyer Jörg , Pritzkow Hans 
Published: July 2007

Highervalent Derivatives of the d‐Metal Acids, 14[1]. — Diimido Complexes [M(NR)2(PMe3)2(L)] of Tetravalent Molybedenum and Tungsten: Structure, Molecular Dynamics, and Activation of π‐Acidic Ligands[M(NMes)2Cl2(dme)] (M = Mo 1, W 2; Mes = mesityl) or the trans‐phosphane complexes [M(NMes)2(PMe3)2Cl2] (3, 4) are reduced by C8K in the presence of PMe3 to give diamagnetic d2 complexes [Mo(NMes)2(PMe3}3] (5) and [W(NMes)2‐(PMe3)3] (6). At least one PMe3 ligand in 5 and 6 is readily substituted by more π‐acidic substrates such as ethene, ethyne, 2‐butyne, and P(OEt)3. The reaction with ethene leads to [Mo(NMes)2(η2‐C2H4)(PMe3)2] (7) and [W(NMes)2‐(η2‐C2H4)(PMe3)2] (8). Furthermore, pentacoordinate complexes [Mo(NMes)2(η2‐C2Me2)(PMe3)2] (9), [W(NMes)2(η2‐C2H2)(PMe3)2] (10), and [W(NMes)2(PMe3){P(OEt)3)2] (11) have been synthesized from 5 or 6. The X‐ray structure analysis of 8 reveals a trigonal‐bipyramidal geometry about tungsten with both arylimido groups perfectly lying in the equatorial mirror plane. The ethene ligand is occupying the third equatorial position. The C2 vector is oriented perpendicular to the WN2 plane. Dynamic NMR studies are consistent with a tbp geometry being also present in solution at the low‐temperature limit. At higher temperatures a rapid exchange of the PMe3 ligands with noncoordinated phosphane according to a dissociative mechanism is observed.
Thianthren‐Radikalkation‐Tetrachloroaluminat
Authors: Bock Hans , Rauschenbach Andreas , Näther Christian , Kleine Markus , Havlas Zdenek 
Published: July 2007

Structures and Molecular Properties of Charge‐Perturbed Molecules, 53[1,2]. — Thianthrene Radical Cation TetrachloroaluminateOne‐electron oxidation of thianthrene, which exhibits a reversible half‐wave potential at + 1.3 V and an irreversible one at + 1.65 V, under aprotic conditions with AlCl3/H2CCl2 yields the violet radical cation salt [H4C6S2C6H4⊕][AlCl4⊖]. Its single‐crystal structure analysis at 90 K reveals an interplanar angle between the phenyl rings of 174° and demonstrates that the neutral sulfur heterocyclic molecule, bent by 128°, is considerably flattened upon one‐electron removal. Semiempirical enthalpy of formation hypersurfaces allow to rationalize the experimental results by a double‐minimum potential for the bent neutral molecule with a rather low inversion barrier and a single minimum one for a planar radical cation. Other radical cation properties such as the spin distribution deduced from its ESR spectrum or the visible absorption maxima near \documentclass{article}\pagestyle{empty}\begin{document}$ \tilde \nu $\end{document} = 11000 and at 18250 cm‐1 corresponding to π → π* and π → σ* transitions are also satisfactorily reproduced by PM3 calculations partly including configuration interaction based on the experimental structure.
Metalloragnische Verbindungen der Lanthanoide, 90[1] [(tert‐Butylcyclopentadienyl)dimethyl(tetramethylcyclopentadienyl)silan]‐Komplexe von Lanthan, Neodym und Lutetium
Authors: Schumann Herbert , Glanz Mario , Hemling Holger 
Published: July 2007

Organometallic Compounds of the Lanthanides, 90[1]. ‐ [(tert‐Butylcyclopentadienyl)dimethyl‐(tetramethylcyclopentadienyl)silane] Complexes of Lanthanum, Neodymium, and Lutetium[(tBuC5H3)SiMe2(C5Me4)]Li2 (1) reacts with LnCl3 (Ln = La, Lu) in THF to yield [(tBuC5H3)SiMe2(C5Me4)]Ln(μ‐Cl)2Li‐(OEt2)2 [Ln = La (3a), Lu (3c)]. The reactions of LnCl3 (Ln = La, Nd) with [(tBuC5H3)SiMe2(C5Me4)]Na2 (2) and (C5Me4H)Na in THF result in the formation of the chiral tris(cyclopentadienyl) complexes [(tBuC5H3)SiMe2(C5Me4)]Ln‐(C5Me4H)(THF) [Ln = La (4a), Nd (4b)]. The 1H‐ and 13CNMR and mass spectra of the new compounds as well as the X‐ray crystal structure of 4a are discussed.
The supramolecular structures of complex tri[gold(I)]sulfonium cations
Authors: Angermaier Klaus , Schmidbaur Hubert 
Published: July 2007

AbstractTris[(trimethylphosphane)gold(I)]sulfonium tetrafluoroborate (1) has been prepared from the corresponding oxonium salt [(Me3P)Au]3O+ BF‐4 and bis(trimethylsilyl) sulfide, (Me3Si)2S. The analogous triisopropylphosphane and methyldiphenylphosphane complexes (2, 3) have been obtained in a similar way. The products are stable crystalline solids, the structure of which has been determined by X‐ray methods. They are composed of independent tetrafluoroborate anions and pyramidal tri(gold)sulfonium cations, which are aggregated to form dimeric units (as in 3) or even strings of dimers (as in 1). It is only in complex 2 that steric effects, originating from the bulky phosphane ligands, prevent the building of supra‐molecular (supracationic) aggregates. In the independent pyramidal cations of 2 only short intracationic Au…Au contacts have been detected. These are complemented by intercationic gold‐gold contacts of similar length in the structures of 1 and 3. ‐ In the preparation of complex 1, the species [(Me3P)Au]4S2+ (BF‐4)2 (4) with hypercoordinate sulfur atoms has also been detected by mass spectroscopy.
Komplexierung von 1,4‐Dihydro‐1,4‐diborafulvenen mit Ni(cod)‐ und Pt(cod)‐Fragmenten
Authors: Gangnus Bernd , Feßenbecker Achim , Pritzkow Hans , Siebert Walter 
Published: July 2007

Complexation of 1,4‐Dihydro‐1,4‐diborafulvenes with Ni(cod) and Pt(cod) Fragments*Reactions of the 1,4‐diborapentafulvene derivatives 1 and 2a, b with M(cod)2 (M = Ni, Pt) yield the complexes [(η5‐1)Ni‐(cod)] (8), [(μ,η2η5‐2a){Ni(cod)}2] (9a), [(μ,η2,η5‐2b){Ni(cod)}2] (9b), and [(μ,η2,η5‐2a){Pt(cod)}2] (10). Compounds 9 and 10 are the first examples of complexes with 2a, b as a μ,η2,η5‐ligand. The X‐ray structure analyses of 9b and 10 are described.
A Comparative Study of the Reactivity of Mn(no)2L2H and Mn(CO)3L2H Complexes (L = Phosphorus Donor)
Authors: Nietlispach Daniel , Bosch Henry William , Berke Heinz 
Published: July 2007

AbstractMn(NO)2L2H complexes [L = PMe3 1a, PEt3 1b, P(OMe)3 1c, P(OEt)3 1d, P(OiPr)3 1e] have been prepared by the reaction of the corresponding Mn(NO)2L2Br compounds with NaBH4 in ethanol. The reactivity of 1a and 1b is compared to that of Mn(CO)3L2H species (L = PMe3 2a, L = PEt3 2b). Compound 1b reacts with weak acids like PhOH, (CF3)2CHOH and CH3COOH to yield Mn(NO)2(PEt3)2X complexes [X = OPh 3a, OCH(CF3)2 3b, OC(O)CH3 3c] and H2. Compound 2b does not undergo reaction with these acids. At room temperature in toluene 1a, b undergo facile CO2 insertion processes, while 2a, b do not show this reactivity even under more rigorous reaction conditions. From 1a, b and CO2 formato complexes Mn(NO)2L2[OC(O)H] (L = PMe3 4a, L = PEt3 4c) are obtained. The reaction of 1b with salicylaldehyde in toluene proceeds with the formation of a [2‐(hydroxymethyl)‐phenoxy]dinitrosylbis(triethylphosphane) manganese complex 5b, which exchanges the phenoxy ligand in the presence of excess of salicylaldehyde to give (2‐formylphenoxy)‐dinitrosylbis(triethylphosphane)manganese (6b) and α,2‐dihydroxytoluene. p‐Hydroxybenzaldehyde, vanilline, and 4‐hydroxy‐3,5‐dimethoxybenzaldehyde and 1b also afford phenoxy derivatives Mn(NO)2(PEt3)2(OAr) [Ar = p‐OC6H4‐CHO 7a; OC6H3‐2‐OCH3‐4‐CHO 7b; OC6H2‐2,6‐(OCH3)2‐4‐CHO 7c] and H2. Compounds 2a, b do not react with any of these hydroxybenzaldehydes. Compounds 1a, b have been converted into Mn(NO)2L2 [(Z)‐C(COOR′)C(R)H] species (L = PMe3, R = H, R′ = Me 8a; L = PEt3, R = H, R′ = Me 8b; L = PMe3 R, R′ = Me 9a; L = PMe3, R = Ph, R′ = Et 10a; L = PMe3, R = COOMe, R′ = Me 11a; L = PEt3, R = COOMe, R′ = Me 11b) in the presence of alkyl propiolates RC≡CCOOMe (R = H, Me, Ph, COOMe; R′ = Me, Et). Similarly, but under more rigorous conditions, insertion of RC≡CCOOMe (R = H, COOMe) into 2a, b occurs and α metalation products Mn(CO)3(PMe3)2[(Z)‐C(COOMe) = CHR] (L = PMe3, R = H 12a; L = PEt3, R = H 12b; L = PMe3, R = COOMe 13a; L = PEt3, R = COOMe 13b) are formed. In the case of the methyl propiolate insertion into 2a, 10% of an additional β‐metalation compound Mn(CO)3(PMe3)2[(Z)‐CH = CH(COOMe)] (12c) have been detected spectroscopically. Compounds 11b and 13a, b have been transformed into manganacyclic complexes MN[C(COOMe)CH(COOMe)]‐(NO)2(PEt3)2 (14b) and MN[C(COOMe)CH(COOMe)]‐(CO)2L2 (L = PMe3 15a; L = PEt3, CO 15b; L = PEt3 15c). Compound 15c has been identified spectroscopically, and 1a, 8a, and 9a have been characterized by X‐ray structure determinations.
One‐Electron Oxidation of Aryltriazenes to Radical Cations
Authors: Dunsch Lothar , Gollas Bernhard , Neudeck Andreas , Petr Andreas , Speiser Bernd , Stahl Hartmut 
Published: July 2007

Abstract3,3‐Dimethyl‐1‐(4‐R‐phenyl)‐ [R = (CH3)2N, C2H5O, CH3O, CH3; 3] and 3‐Methyl‐1‐(4‐R1‐phenyl)‐3‐(4‐R2‐phenyl)triazenes [R1 = (CH3)2N, CH3O, NO2, R2 = CH3O, H, 4] are oxidized electrochemically and chemically to their one‐electron oxidation products. Cyclic voltammograms of the triazenes are discussed, and ESR as well as UV/Vis spectra of the radical cations are presented. The stability of the triazene radical cations generated depends on the substituents on the aryl rings. 4‐R‐Benzenediazonium ions are identified as one of the decay products of the radical cations by means of cyclic voltammetry and UV/Vis spectroelectrochemistry.
Organic Syntheses via Transition Metal Complexes, 74[1] Novel Phosphonium Allenide and 2‐Phosphanylethenyl Carbene Chromium and Tungsten Complexes
Authors: Aumann Rudolf , Jasper Beate , Läge Mechtild , Krebs Bernt 
Published: July 2007

AbstractAlkynylcarbene complexes (CO)5MC(OEt)‐C≡CR 1 (M = Cr, W; R = Ph, tBu, SiMe3) readily add tertiary phosphanes PPhR2′ 4 (R′ = Ph, Me) to form stable zwitterionic phosphonium allenide complexes (CO)5M‐‐C(OEt) = CC(R)‐P+PhR2′ 5. Complex 5a (M = Cr, R = R′ = Ph) was characterized by X‐ray diffraction. The addition of secondary phosphanes PHR2 6 to 1 affords red (2‐phosphanyl ethenyl)‐carbene complexes (CO)5MC(OEt)‐CHC(R)‐PR2 (E)‐8 (R = tBu, cC6H11, Ph) in 34–89% isolated yields. Dinuclear complexes (CO)5MC(OEt)‐CHC(R)‐P(R2)M(CO)5 (E)‐9 are obtained as byproducts. Compounds (E)‐8b (M = Cr, R = cC6H11) and (E)‐9i (M = Cr, R = Ph) were characterized by X‐ray analyses.
Synthesis and Complexation of a New 14‐Membered N2O2 Macrocycle with vic‐Dioxime Moieties
Authors: Hamuryudan Esin , Bekaroǧlu ÖZer 
Published: July 2007

AbstractThe new vic‐dioxime ligand 2 (LH4) carrying a 14‐membered N2O2 macrocycle has been prepared. Mononuclear complex (LH3)2Ni, trinuclear complexes (LH)2Cu3, (LH)2Co3, (LH)2‐Pd3, and (LH)2Co3(py)3Cl3, dinuclear complex (LH3)2‐(UO2)2(OH)2, and pentanuclear complex [L2Cu5(phen)2]‐(NO3)2 have been synthesized from LH4. The electrochemical properties of tri‐ and pentanuclear complexes were investigated by cyclic voltammetry. For (LH)2Cu3 two reduction waves appeared at 0.215 and ‐0.870 V. [L2Cu5(phen)2](NO3)2 exhibited four reduction waves at 0.200, ‐0.025, ‐0.670, and ‐1.170 V.
Derivatives of Aza‐nido‐tetraborane and Diaza‐arachno‐pentaborane from Tri‐tert‐butylazadiboriridine
Authors: Müller Matthias , Wagner Trixie , Englert Ulli , Paetzold Peter 
Published: July 2007

AbstractThe Lewis acids RBH2 are added to the basis B‐B bond of tri‐tert‐butylazadiboriridine, NB2tBu3 (1a), to give 5‐alkyl‐1,2,3‐tri‐tert‐butyl‐1‐aza‐nido‐tetraboranes of type 3 (two endo‐H atoms at B5) or type 4 (one H atom in a B2–B5 bridging position, one exo‐H atom at B5), either as a mixture of 3 and 4 (3, 4b–d: R  Me, tBu, CMe2iPr) or with the isomer 4 in high excess (4e, f: R  Ph, sBu). The reaction of dialkylboranes R2BH with 1a yields 5,5‐dialkyl‐1,2,3‐tri‐tert‐butyl‐1‐aza‐nido‐tetraboranes of type 4 (one H atom in a B2‐B5 bridging position; 4g, h: R2  Et2, cycloocta‐1,5‐diyl). In boiling THF, trialkylboranes BR3 transform 1a into NB2tBu2R which, expectedly, dimerizes spontaneously to give a dialkyltetra‐tert‐butyl‐2,5‐diaza‐nido‐hexaborane of type 2 (2a, b: R  Me, Et). The products of the addition of aminoboranes H2BNRR' to 1a are identified as alkyl derivatives of 2,5‐diaza‐arachno‐pentaborane, N2B3tH2tBu3RR' (5a–d, R/R' = H/Pr, H/tBu, Me/Me, Et/Et). The aminoborane H2B  NiPr2 with a sterically more demanding amino group hydroborates the B‐B bond of 1a to give the acyclic product iPr2NBH‐B(tBu)‐N(tBu)B(tBu)H (6). In contrast to the B atoms, the N atoms in the electron‐deficient cluster skeletons of 2–5 need not take part in (3c,2e) bonds of the s̀ type. The molecular structures of 4c, 5d, and 6 are confirmed by X‐ray structural analyses.
New Pathways in Tellurium‐Chalkogen‐Nitrogen Chemistry: Preparations, Structures, and Properties of Telluraheterocycles
Authors: Haas Alois , Pryka Michael 
Published: July 2007

AbstractTreatment of Se(NSO)2 with TeF4 in CH2Cl2 yields the compounds (4a) and (5b), while with TeBr4 after six months (2d) is formed. An almost quantitative yield of Cl4Te2N4S2 (6) is obtained from either Cl6Te2N2S (1a) and (CH3)3SiNSNSi(CH3)3 in CH2Cl2 at 20°C (2 d) or TeCl4 and (CH3)3SiNSO (molar ratio 1:2) in CH2Cl2 at 60°C (3 d). The use of (CH3)3SiOSi(CH3)3 as solvent in the last mentioned procedure gives 1a and small amounts of Cl2Te(NSO)2. Similarly, F2Te(NSO)2 is prepared from TeF4 and (CH3)3SiNSO in CH2Cl2. Dechlorination of 1a with (C6H5)3Sb leads to (2a), which is also produced from TeCl4 and [(CH3)3Si]2NSN[Si(CH3)3]2. When TeF4 is used instead of TeCl4 (molar ratio 3:1) the salt (7a) is formed. Similarly, (7b) is prepared from 2a and AsF5 or Ag+[AsF−6] in SO2. A new method for the preparation of bicyclic type 1 telluraheterocycles involves bromination of 2a yielding Cl2Br4Te2N2S (1b). Dehalogenation with (C6H5)3Sb converts 1b into (2b). When 2b is treated with Br2 in CH2Cl2 an oxidative halogenation takes place with formation of Br6Te2N2S (1c). Metathetical exchange between 2b and Ag+[AsF−6] gives (7c). Isostructural S(NSO)2 reacts with TeCl4 for several weeks at 60°C in CH2Cl2 to form S4N4. TeCl4 and [S5N+5][Te3Cl−3], in contrast to the corresponding reaction with Se(NSO)2. The molecular structures of 4a, 7b, 8, and [S5N+5][Te3Cl−13] have been determined by X‐ray diffraction methods. Spectroscopic data for all new compounds are presented.
Tellurium Polycations by Oxidation of Tellurium with Tungsten Halides Syntheses and Crystal Structures of Te6(WOCl4)2 and Te6I2(WCl6)2
Authors: Beck Johannes 
Published: July 2007

AbstractWOCl4 reacts at 200°C with tellurium in a sealed, evacuated ampoule with the formation of Te6(WOCl4)2. The structure consists of six‐membered tellurium rings in a boat conformation with significant transannular interactions and of pyramidal WOCl4 units which are linked by linear asymmetric O...;WO bridges to polymeric (WOCl4)n, chains. The observed paramagnetism is consistent with the ionic formulation Te2+6[(WOCl−4)2]n. In the reaction of WCl6, I2 and Te in a 2:1:6 ratio Te6I2(WCl6)2 is formed at 150°C. The crystal structure consists of Te6I2+2cations and of slightly distorted octahedral WCl−6 anions. The Te6I2+2 ions are isostructural with Se6I2+2 and consist of a six‐membered ring of Te atoms in the chair conformation with two I atoms bound in the 1,4‐positions.
The Structures of [X2YNYX2]+ Cations (X  F, Cl; Y  S, Se). A Comparison of X‐ray and ab Initio Studies[1]
Authors: Schulz Axel , Broschag Matthias , Tornieporth‐Oetting Inis C. , Klapötke Thomas M. , Buzek Peter , Schleyer Paul Von Ragué , White Peter S. 
Published: July 2007

AbstractThe structures of cationic species of the series [X2YNYX2]+ (X  F, Cl; Y  S, Se) have been computed ab initio using all electron treatments for first‐row elements and sulfur and quasi‐relativistic pseudopotentials for Se and Cl. Splitvalence basis sets with polarization and diffuse functions were employed. The MP2 results for the (non‐isostructural!) cations [Cl2SeNSeCl2]+ (1: Cs) and [F2SNSF2]+ (2: C2v) are in excellent agreement with the experimental (X‐ray) observations. Both structures represent local minima. A deeper minimum for either of the cations is represented by another C2v isomer which for crystal lattice energy reasons is stable in the isolated state only. The geometries of the hitherto unknown species [Cl2SNSCl2]+ (3) and [F2SeNSeF2]+ (4) have been assessed by ab initio HF calculations. In analogy to 2, cations 3 and 4 are predicted to prefer C2v symmetry. Therefore, 1 exhibits unusual structural features. According to strictly localized natural bond orbital analysis (NBO), the central nitrogen atoms in 1 and 2 possess two lone pairs of electrons (LP: one sp hybrid and one p orbital). The relatively short SeN and SN bond distances in 1 (1.741–1.760 Å) and 2 (1.551 Å) can best be attributed to LP(N)→s̀*(YX) negative hyperconjugation (1: Y  Se, X  Cl; 2: Y  S, X  F).
Übertragung eines cyclo‐E5‐Liganden (E  P, As) von einem Eisen‐ auf ein Ruthenium‐ und ein Osmium‐Zentrum
Authors: Rink Barbara , Scherer Otto J. , Wolmershäuser Gotthelf 
Published: July 2007

AbstractTransfer of a cyclo‐E5 Ligand (E  P, As) from an Iron to a Ruthenium and an Osmium Center☆The thermolysis of [Cp*Fe(η5‐E5)] (1) and [{Cp*M(CO)2}2] (2, 3) affords by cyclo‐E5 transfer the sandwich complexes [Cp* M(η5‐E5)] (4a, b: M  Ru, E  P, As; 4c: M  Os, E  P). The crystal‐structure analysis of [(C5Me4Et)Os(η5‐P5)] (4c') confirms its sandwich‐type structure.
Selective Activation of Aromatic C—H Bonds with Lithium Atoms at 77 K
Authors: Tacke Matthias 
Published: July 2007

AbstractIn the presence of donor bases like THF lithium atoms are able to activate benzene derivatives under cryogenic reaction conditions. Only ring‐metalated products and solid lithium hydride are formed selectively. The thermodynamically favored product benzyllithium or biphenyl generated by dimerization of free phenyl radicals are not found. This is one of the very few examples of metal atoms undergoing a C—H activation without further photoexcitation.
Zerfall von Nitrosylazid, N4O: Existieren auch cyclische Stickstoff‐Oxide?
Authors: Klapötke Thomas M. , Schulz Axel 
Published: July 2007

Decomposition of Nitrosyl Azide, N4O: Are Cyclic Nitrogen Oxides Existent?The unimolecular decomposition of nitrosyl azide (tetranitrogen monoxide), N4O, was studied at the electron‐correlated, spin‐restricted RMP2 level with the 6–31G(d,p) and 6–31+G* basis sets. Frequency calculations were performed at 6–31+G* on the optimized structures. It is demonstrated that the experimentally established trans‐trans‐N4O (Cs) may either interconvert into cis‐cis‐N4O which upon decomposition forms cyclic N4O (C2v) as an intermediate species to finally give N2O (C∞v) and N2, or trans‐trans‐N4O may directly dissociate into cyclic N2O (C2v) and N2. All structures determined were rationalized by energy hypersurface calculations.
Photocatalytic Oxygenation of Selected Cycloalkenes in Aqueous Solutions Induced by Water‐Soluble Metal Porphyrin Complexes
Authors: Hennig Horst , Behling Jördis , Meusinger Reinhard , Weber Lutz 
Published: July 2007

AbstractWater‐soluble manganese(III) as well as iron(III) porphyrinates are introduced as light‐sensitive precursor compounds for the photocatalytic activation of dioxygen in aqueous solutions. It is shown that in the presence of α‐pinene (4) and the further cycloalkenes 11–13 photocatalytic oxygenation reactions occur. The dependence of the selectivity of the oxygen transfer to the olefin on both the presence of water and the variation of the substrate‐to‐catalyst ratio is discussed. The catalyst may be conveniently separated from the substrates/products by using aqueous solvent systems.
Enantioselektive Katalyse, XI. Darstellung von optisch reinen Diphosphanen mit vier Stereozentren
Authors: Nagel Ulrich , Krink Thomas 
Published: July 2007

Enantioselective Catalysis, XI. – Preparation of Optically Pure Diphosphanes with Four Stereogenic CentersWe synthesized a number of new diphosphanes with four stereogenic centers and two different aryl groups on each phosphorus atom. Starting with the diastereomeric mixture of [P(R,S),3R,4R,P′(R,S)]‐1‐(tert‐butoxycarbonyl)‐bis(phenyl‐phosphanyl)pyrrolidine (1a,b,c) we prepared the corresponding chlorophosphanes by use of chlorotrimethylsilane followed by treatment with hexachloroethane. The chlorophosphanes react with Grignard. or organolithio compounds to the target molecules. For the chromatographic separation and purification of the diastereomers we transformed them into their Pdl2 complexes (Pd‐4a,b,c to Pd‐12a,b,c). The structures of Pd‐4a, Pd‐4c, Pd‐6c, Pd‐8b and Pd‐9a were determined by X‐ray diffraction analysis. A correlation between structural parameters of these Pd complexes and the enantio‐selection for rhodium complexes of the same ligands as hydrogenation catalysts is suggested.
(C5H5)Co‐Induced Head‐Head Coupling of Dimethylfulvene: Formation, Molecular Structure and Electrochemistry of (1,1,2,2‐Tetramethyl‐1,2‐ethanediyl)bis(cobaltocene)
Authors: Wadepohl Hubert , Lieth Claus‐Wilhelm Von Der , Paffen Franz‐Josef , Pritzkow Hans 
Published: July 2007

AbstractHead‐head coupling of a dimethylfulvene ligand occures in the reaction of 6,6‐dimethylpentafulvene (1a) with [(C5H5)Co(C2H4)2] (7) to give (1,1,2,2‐tetramethyl‐1,2‐ethanediyl)bis(cobaltocene) (8a). In contrast, the mononuclear η4‐fulvene complexes 3b, c are obtained from 6‐ethyl‐6‐methyl‐(1b) and 6,6‐diethylfulvene (1c) and 7. The crystal structures of 8a and the corresponding bis(ferrocene) 9a have been determined. The electrochemical behaviour of 8a and 9a shows 8a+, 8a−, and 9a+ to be localised mixed‐valence species. Molecular mechanics calculations have been performed on the title complex and related derivatives.
Ylidyl‐dihalogenphosphane – Strukturbilder einer sich anbahnenden Dissoziation
Authors: Schmidpeter Alfred , Nöth Heinrich , Jochem Georg , Schrödel Hans‐Peter , Karaghiosoff Konstantin 
Published: July 2007

Ylidyl‐dihalophosphanes Provide Structural Snapshots on Their Way to DissociationThe reaction of phosphonium ylides with phosphorus trihalides has been studied for the synthesis of ylidyl‐dihalophos‐phanes (= dihalophosphanyl ylides) Ph3PCRPX2 3, X = Cl, and 9, X = Br. Compounds 3, R = aryl, are readily prepared from the phosphonium bromides [Ph3PCH2R]Br, compounds 3, R = alkyl, SiMe3 or PCl2, and 9 are obtained from silylylides Ph3PCRSiMe3, compound 3, R = PPh3+ results from the addition of PCl3 to the hexaphenylcarbodiphosphorane. A (β‐morpholinovinyl)dichlorophosphane 12 has also been prepared. Ylides 3 are oxidized by sulfur and selenium and are converted to ylidyl‐chlorophosphenium (= chloro‐phosphaalkenyl‐phosphonium) salts [Ph3PCRPCl]AlCl4 10. In the 31P‐NMR spectra of 3 and 9 the geminal coupling 2JPP indicates the phosphorus lone pair to be synperiplanar to the phosphonio group. In one case the P(III)C rotation barrier has been estimated from VT‐31P‐NMR spectra. By X‐ray crystallography the structures of 3, R = Me, 2,6‐Cl2C6H4, 4‐NO2C6H5, PCl2, of 9, R = Me (two molecules), SiMe3, of an ylidyl‐selenophosphonyl dichloride (11b), and of 12 have been analyzed. They provide representatives for the full range of rotation from the symmetric conformer with two equal PX bonds to the conformer with one PX bond perpendicular to the PCP plane and with this bond being extremely elongated. Thus, they map out the pathway to PX bond breaking. On this way the initial charge transfer from the ylidic carbon to the antibonding PX orbital ends up in a π donation and PX dissociation.