SYNTHESIS OF N,N-DIALKYLCARBAMATO COMPLEXES OF GROUP-4 METALS (TI, ZR, HF) BY THE METAL CHLORIDE-NHR2-CO2 SYSTEM (R = ET OR PRI) - CRYSTAL AND MOLECULAR-STRUCTURE OF [HF(O2CNPRI2)4]

The compounds [M(O2CNR2)4] (M = Ti, Zr or Hf; R = Et or Pr) have been prepared by treating the corresponding metal tetrachloride with CO2-NHR2 in toluene. The structure of [Hf(O2CNPr2i)4] has been solved by X-ray diffraction methods. Crystal data: monoclinic, space group P2(1)/c, a = 12.756(3), b = 22.131(9), c = 14.548(5) angstrom, beta = 113.03(2)-degrees and Z = 4. It consists of monomeric units, the hafnium atom being surrounded by the eight oxygen atoms of the four N,N-diisopropylcarbamato groups in a slightly distorted dodecahedral arrangement. By reaction with anhydrous hydrogen halides HX (X = Cl, Br or l) the hexahalogenometalate(iv) anions, [MX6]2-, as the diethylammonium derivatives, have been obtained in high yields. The redox reaction between [Ti(O2CNEt2)4] and [V(eta-C5Me5)2] gives the titanium(III) and vanadium(III) complexes [{Ti(O2CNEt2)3}n] and [V(eta-C5Me5)2(O2CNEt2)], respectively.