Oliver Steigelmann

Phosphinomethanid-komplexe der lanthanoide

Abstract By reaction of LnI2 · 2THF, Ln  Yb, Sm with the phosphinomethanides Li[C(PMe2)2X], X  SiMe3, PMe2 the addition products {(THF)Ln[C(PMe2)2X]2I2Li(THF)}, Ln  Yb, X  SiMe3 (1a), X  PMe2 (1b) and Ln  Sm, X  SiMe3 (2) are obtained; 1a could be characterized by X-ray crystal structure analysis. In contrast complete substitution is achieved in the reaction of lanthanide triflates with lithium phosphinomethanides. Thus the seven-coordinated and X-ray structurally characterized complex {(THF)Lu[C(PMe2)2(SiMe3)]3} (3) is obtained. Lu[C(PMe2)2(SiMe3)]3 (4) could be obtained from 3 by removing thf in vacuo or by reaction of Lu(CF3SO3)3 with Li[C(PMe2)2(SiMe3)] in toluene. The derivative {(THF)Lu(Me)[C(PMe2)2(SiMe3)]2} (5) has been isolated by treatment of 3 with LiMe. In a somewhat random way, one run with LiMe gave the X-ray structurally characterized, anionic complex [(THF)4Li]{Lu(OSiMe3)[CPMe2)2(SiMe3)]3} (6) obviously by cleavage of silicon grease. A coordination number of eight is observed in the anionic complexes {Ln[C(PMe2) 2(SiMe3)]4Li}, Ln  Er (7), Y (8) und La (9). The X-ray crystal structure of 9 verifies the new type of an eightfold phosphorus coordinated lanthanoid center. In compounds Sc[C(PMe2) 2X)]3, X  SiMe3 (10a) and X  PMe2 (10b) the phosphino-methanide ligands are arranged in an intermediate coordination mode between σ-chelating and π-type coordination as revealed by X-ray diffraction. The X-ray structurally characterized dimeric complex {Sm[CH(PMe2)2]3} 2 (11) combines two different phosphinomethanide coordination modes. Two phosphinomethanide ligands in 11) adopt a π-type coordination, the third ligand is arranged in a η2, μ-C,P fashion.

Tuning the interaction between paramagnetic metallocenes. Doubly silyl-bridged chromocenes

Doubly silyl-bridged cyclopentadienyl anion (L2–), chromium(II) chloride and cyclopentadienyl anion (Cp–) react to give the dinuclear chromocene CpCrLCrCp with a metal–metal distance of 5.831(1)A(X-ray determination) that has magnetically probably isolated chromocene moieties (NMR, magnetic susceptibility) but which show interactions in cyclic voltammetry.

Synthesis and Structure of a New Chiral Oxaziridine from (3-Oxo-camphorsulfonyl)imine

Oxidation of (3-oxo-camphorsulfonyl)imine (1) by magnesium monoperoxyphthalate does not lead to the oxaziridine obtained with 3-chloro-perbenzoic acid, but to a new chiral oxaziridine containing an additional oxygen atom (Baeyer-Villiger type oxidation). The structure of the product is established by X-ray crystallography, and reaction pathways for the oxidation of 1 by peracids are discussed.

Gold(I)-Komplexe sekundärer Phosphine / Gold(I) Complexes of Secondary Phosphines

Gold(I) complexes with secondary phosphines R2PH (la—d) of the type R2PH · AuCl (2a—d) have been obtained in good yield from reactions of (carbonyl)chlorogold(I) and the corresponding ligand in diethylether. Both compounds 2a, b bearing aromatic substituents with R = 2,4,6-trimethylphenyl (mesityl) and 2-methylphenyl (o-tolyl), and compounds 2c, d with the bulky alkyl substituents R = t-butyl and R = cyclohexyl, resp., are air-stable crystalline solids. — The coordination compounds have been characterized by NMR and IR data, and — in the cases of 2b and 2c — by single crystal X-ray diffraction studies. Crystals of these two compounds are both monoclinic, space group P21/c with four formula units (Z = 4). The analysis shows independent monomers for compound 2c with no intermolecular Au···Au contacts. Molecules of 2b are arranged in centrosymmetrical dimers (head to tail) with an Au···Au distance of 3.56 Å and a dihedral angle P—Au—Au′—P′ of 180°. (This structural study is as yet incomplete and suffers from an unsatisfactory data set for 2b.) It appears that intermolecular contacts are largely controlled by steric effects.

Dinuclear Gold(I) Chloride Complexes of 1,4-Bis(diphenylphosphinyl)butane and 1,5-Bis(diphenylphosphinyl)pentane: A Conformational Study

[1,4-Bis(diphenylphosphinyl)butane]digold dichloride 1 and [1,5-bis(diphenylphosphinyl)-pentane]digold dichloride 2 have been prepared from R2SAuCl (R = CH2CH2OH) and the corresponding bidentate phosphines Ph2P(CH2)nPPh2 (n = 4 or 5) in good yields. The structures of the compounds have been determined by single crystal X-ray diffraction (1 · CH2C12: space group P1̅, Z = 2; 2·0.5 CH2Cl2: space group C 2/c, Z = 8). While the monomers [Ph2P(CH2)5PPh2] (AuCl)2 are associated through intermolecular Au···Au contacts (3.323 Å) to form a chain-like structure, the crystal lattice of 1· CH2Cl2 features independent [Ph2P(CH2)4PPh2](AuCl)2 molecules which show no intra- or intermolecular Au···Au interactions. This exceptional behaviour can be rationalized on the basis of efficient packing of solvent molecules and molecules 1 with a particularly favourable conformation, which cannot be altered by weak Au(d10)—Au(d10) interactions.

Substituenteneinflüsse auf Synthese und Eigenschaften von Hexakis[phosphanaurio(I)]methanium(2+)bis(tetrafluoroboraten) / Substituent Effects in Synthesis and Properties of Hexakis[phosphineaurio(I)]methanium(2 +) Bis(tetrafluoroborates)

Polyaurated carbon complexes of the type [(L–Au)6C]2+ with functionalized phosphine ligands have been prepared by the reaction of the phosphinegold(I) chlorides R(Ph)2PAuCl (R = p-C6H4-Cl 2a,p-C6H4-Br 2b,p-C6H4-CH3 2c,p-C6H4-OCH3 2d,p-C6H4-COOH 2e, p-C6H4–N(CH3)2 2f), R2(Ph)PAuCl (R = p-C6H4-N(CH3)2 2g) and R3PAuCl (R = p-C6H4-N(CH3)2 2h) with tetrakis(dimethoxyboryl)methane in HMPT at room temperature. Clearly depending on the different inductive and mesomeric effects, the preparation of the clusters with substituents like –CH3 3c, –OCH3 3d and –N(CH3)2 3f needs shorter reaction times and the products show better solubility in organic solvents than those with functional groups like –Cl 3a, –Br 3b and –COOH 3e. The 31P magnetic resonance parameters are correlated with electronic effects of the substituents, but the chemical shift of the interstitial carbon atom in the 13C-NMR spectra is largely independent of the coordinating ligands. For the phosphinegold(I) chlorides 2f–h X-ray structure analyses have been performed.

[(2-Methylphenyl)phosphin]gold(I)-bromid: Eine neue Strukturvariante für intermolekulare Au ··· Au-Kontakte bei (Phosphan)gold(I)-halogeniden / [(2-Methylphenyl)phosphine]gold(I) Bromide: A New Type of Structure for Au ··· Au Contacts in (Phosphine)gold(I) Halides

(2-Methylphenylphosphine)gold(I) bromide has been prepared from tetrabutylammonium dibromoaurate(I) and the primary phosphine in almost quantitative yield. The structure of the compound has been determined by single crystal X-ray diffraction (space group C2/c, Z = 8). The monomer units (2-MeC6H4PH2)AuBr with an almost linear P—Au—Br axis are aggregated in the solid through short Au ··· Au contacts to give folded chains of gold atoms with alternating Au · · · Au distances of 3.097(1) and 3.380(1) A, respectively, a repetitive angle AuAuAu of 103.5(1)°, and alternating dihedral angles AuAuAuAu of 180 and ± 104.5°, respectively. The monomers in adjacent dimers (RPH2AuBr)2 are related crystallographically by a center of inversion or by a two-fold axis, respectively.

π-complexes of p-block elements: [(η6-C6Me6)Sn(AlCl4)2]2•3 C6H6 ― a dimeric coordination compound of hexamethylbenzene with Sn(AlCl4)2

Dimeric (η6-hexamethylbenzene)tin(II)bis(tetrachloroaluminate), [(η6-C6Me6)Sn(AlCl4)2]2, has been obtained from the reaction of anhydrous SnCl2, AlCl3, and hexamethylbenzene in the molar ratio of 1:2:1 in benzene as a solvent. The complex, which crystallizes in the triclinic space group PĪ, contains a folded eight-membered ring Al2Sn2Cl42+, with the two tin(II) centers linked by two bidentate bridging AICl4- counterions. Each tin(II) atom is η6-bonded to a hexamethylbenzene ring at a distance of 2.45 Å — the shortest Sn-to-arene distance ever found in the tin(II)/arene system. Each tin(II) atom is further connected to another AICl4- anion, also acting as a bidentate ligand, but without contacts to other tin(II) centers. The three crystal benzene molecules show no specific metal contacts.