Controlled hydrolysis reactions of solvated [TiCl n ] (4–n)+ species. Crystal and molecular structures of [Mg(MeCN) ₆ ][{TiCl ₄ (MeCN)} ₂ (µ-O)]·4MeCN and [{TiCl ₂ (MeCN) ₂ (µ-O)} ₄ ]·2MeCN

Partial hydrolysis reactions of the solvated [TiCl5(MeCN)]– anion and of the adduct TiCl4·2MeCN gave the µ-oxo-dititanium anion [{TiCl4(MeCN)}2(µ-O)]2– and the neutral tetranuclear µ-oxo compound [{TiCl2(MeCN)2(µ-O)}4], respectively, as established by X-ray crystallographic studies. Crystals of [Mg(MeCN)6][{TiCl4(MeCN)}2(µ-O)]·4MeCN 1 are monoclinic, space group P21/n, a= 14.777(6), b= 14.603(6), c= 21.214(10)Å, β= 105.3(1)°. The structure contains discrete octahedral [Mg(MeCN)6]2+cations, [{TiCl4(MeCN)}2(µ-O)]2– anions and solvent (MeCN) molecules. Crystals of [{TiCl2(MeCN)2(µ-O)}4]·2MeCN 2 are orthorhombic, space group P212121a= 12.165(6), b= 12.367(6), c= 27.927(11)Å. The structure contains discrete [{TiCl2(MeCN)2(µ-O)}4] units and solvent (MeCN) molecules. In 1 both titanium atoms have an octahedral environment. The Ti–O–Ti bridge is approximately linear [174.7(3)°] with equivalent Ti–O distances of 1.783(4) and 1.764(4)Å. By contrast in 2 there are four Ti–O–Ti bridges but in each case the two Ti–O distances are significantly different with mean values of 1.668,1.954 Å.