Synthesis of N,N-dialkylcarbamato complexes of Group 4 metals (Ti, Zr, Hf) by the metal chloride–NHR₂–CO₂system (R = Et or Prⁱ): crystal and molecular structure of [Hf(O₂CNPrⁱ₂)₄]

Abstract

The compounds [M(O2CNR2)4](M = Ti, Zr or Hf; R = Et or Pri) have been prepared by treating the corresponding metal tetrachloride with CO2–NHR2 in toluene. The structure of [Hf(O2CNPri2)4] has been solved by X-ray diffraction methods. Crystal data: monoclinic, space group P21/c, a= 12.756(3), b= 22.131(9), c= 14.548(5)Å, β= 113.03(2)° 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 I) 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(η-C5Me5)2] gives the titanium(III) and vanadium(III) complexes [{Ti(O2CNEt2)3}n] and [V(η-C5Me5)2(O2CNEt2)], respectively.