Wolfgang Kläui

Catalytic Copolymerization of Ethene and Carbon Monoxide on Nickel Complexes

Can palladium be replaced by nickel? For the industrial copolymerization of carbon monoxide and ethene a palladium catalyst is used which cannot be recovered-a cheaper procedure would be desirable. The presented complex 1 is the first structurally characterized nickel compound which does not polymerize ethene but a mixture from carbon monoxide and ethene unter mild conditions to give a perfectly alternating polyketone.

Molecular structures and solid-solid phase transitions of trinuclear CpCo[P(O)(OR)2]32M complexes

SummaryThe trinuclear complexes {CpCo[P(O)(OMe)2]3}2Co and {CpCo[P(O)(OEt)2]3}2M, where M=Mg, Ca, Sr, Ba, Pb, Mn, Co, Ni, Cu, Zn, Cd or Hg, have been studied by x-ray diffraction methods and the crystal structures of {CpCo[P(O)(OR)2]3}2M [R=Me with M=Co (1) and R = Et with M = Cu (2)] have been solved by the heavy atom technique. Complex (2) crystallizes in the triclinic space group P 1 with two crystallographically independent molecules per unit cell. The cell dimensions area = 12.195(3) Å,b = 20.429(6) Å, c = 12.518(3) Å,α = 102.39(2)°, β=120.15(2)°, γ=92.28(2)°. The molecule contains two cobalt atoms and one copper atom in a linear arrangement with copper situated on a center of symmetry. Each of the cobalt atoms is bonded to a cyclopentadienyl ring and is connected to the central copper atom by three phosphonate groups acting as bridging ligands. Disorder phenomena within these phosphonate groups are best described as an enhanced thermal motion corresponding mainly to a rotation around the Co-Cu-Co axis. The CuO6 coordination octahedra exhibit a small (4+2) distortion.The electronic spectrum of this copper complex has been measured in solution and in the solid state and is in accord with the Jahn-Teller distorted octahedral coordination of the copper ion found in the x-ray structure.Complex (1) is monoclinic, space group P21/c with two formula units per cell. Its molecular structure shows the same general features as the copper complex. The coordination of the central cobalt atom is regularly octahedral within the limits of error. Parts of the phosphonate P(O)(OMe)2 groups are disordered over two distinct sites in the crystal with occupancy factors ofca. 0.75 and 0.25.D.s.c. measurements of the trinuclear compounds containing disordered P(O)(OEt)2 groups show phase transitions occurring in the 160–230 K temperature range that are best discussed in terms of order-disorder transitions. From d.s.c. measurements of the corresponding complexes with P(O)(OMe)2 ligands, there are no phase transitions visible in the 100–300 K range.

Untersuchungen zur reaktivität von metall-π-komplexen XX. nachweis der sterospezifischen ringprotonierung von nickelocen

Abstract Nickelocene reacts with CF 3 COOH to give [C 5 H 5 NiC 5 H 6 ] + . Deuteration experiments confirm that the entering proton occupies the exo -methylene position, i.e. the attack of the electrophile occurs at one of the ring ligands and not at the metal.

Bis-olefin-rhodium(I) complexes of a tripod ligand with an O,O,O-donor set

Abstract The organometallic anion [(C 5 H 5 )Co{P(O)(OC 2 H 5 ) 2 } 3 ] − reacts as a tridentate oxygen ligand L − with [{RhCl(diolefin)} 2 ] (diolefin = 1,5-cyclooctadiene, norbornadiene, tetrafluorobenzobarrelene, trimethyltetrafluorobenzobarrelene, duroquinone) and with [{RhCl(C 2 H 4 ) 2 } 2 ] in hexane or in acetone in the presence of AgClO 4 to give air stable compounds of the type [LRh(diolefin)] and [LRh(C 2 H 4 ) 2 ]. These novel five-coordinate Rh 1 complexes are fluxional molecules. They have been characterized by elemental analysis, and 1 H NMR, IR and mass spectroscopy.

Spectroscopic characterization, electrochemistry and single-crystal structure of bis[chlorobis (dimethylphosphito-p)(hexamethylbenzene) ruthenium(II)-μ-(O,O,Cl)]Copper(II) dichloromethane (1:2), an unusual linear, heterotrinuclear complex

Abstract The X-ray crystal structure of the heterotrinuclear compound [Cu{ClRu[(MeO) 2 PO] 2 (C 6 Me 6 )} 2 ]·2CH 2 Cl 2 is described, together with its spectroscopic and electrochemical properties. The copper ion is tetragonally coordinated by four, short copper-oxygen bonds [Cuue5f8O = 1.931(4) and 1.965(4) A] and two, long Cuue5f8Cl bonds of 2.881(2) A. The chloride ions bridge directly between the copper and ruthenium, with Ruue5f8Cl = 2.292(2) A and Ruue5f8Clue5f8Cu = 93.6(1)°. The other bridging ligands are the OP(OMe) 2 − ligands, which coordinate to copper with oxygen and to ruthenium with phosphorus. The ruthenium coordination is completed by the η 6 -C 6 Me 6 ligand. The structure of the complex is retained in solutions of CH 2 Cl 2 and CH 3 CN. Electrochemical studies (CV and DPP) show that both ruthenium(II) ions can be oxidized subsequently at, respectively, 0.69 and 0.87 V. The copper(II) ion is not redox active. The compound has been further characterized by ligand-field spectra and EPR spectra for copper(II). These spectra agree with a tetragonal chromophore CuO 4 Cl 2 , both for the solid and the (frozen) solution.