ELECTRON-TRANSFER AND LIGAND-TRANSFER REACTIONS INVOLVING N,N-DIALKYLCARBAMATES - SYNTHESIS AND MOLECULAR-STRUCTURE OF V2[ETA-5-(C5H5)]2[O2CN(C2H5)2]4

Abstract

Electron- and ligand-transfer reactions of low-valent organometallic compounds of titanium and vanadium with N,N-dialkylcarbamates of titanium(IV) are reported. The reaction of VCp2 (Cp = eta(5)-cyclopentadienyl) with Ti(O2CNEt2)4 affords, inter alia, the dimeric vanadium(III) N,N-diethylcarbamato derivative V2Cp2(O2CNEt2)4 which has been studied by X-ray diffraction methods. Crystal data: triclinic, space group P1BAR; a = 10.802(2), b = 11.004(1), c = 8.960(1) angstrom; alpha = 112.879(9), beta = 102.66(1), gamma = 102.42(1)-degrees; V = 902.3(6) angstrom 3; Z = 1; F(000) = 368, rho(calc) = 1.282 g cm-3; mu = 5.47 cm-1. It consists of a centrosymmetric dimer, the two vanadium atoms being surrounded by four oxygen atoms of the bridging N,N-diethylcarbamato groups and by the cyclopentadienyl ligand. The metal atom exhibits a distorted square-pyramidal coordination geometry with the oxygen atoms occupying the basal plane. The reaction of TiCp2(CO)2 or Vmes2 (mes = eta(6)-1,3,5-Me3C6H3) with Ti(O2CNEt2)4 affords Ti(III) and V(III) N,N-diethylcarbamato derivatives by a simultaneous ligand- and electron-transfer reaction. Magnesium N,N-diisopropylcarbamate, Mg(O2CNPr2i)2, has been obtained by a ligand-transfer reaction between MgCp2 and Ti(O2CNPr2i)3