Interaction modes of titanium tetrachloride with the carbonyl functionality

Mesityl aldehyde binds TiCl4 leading to the first structurally characterized TiCl4-aldehyde adduct, cis-[(MesCHO)(2)TiCl4] (Mes = 2,4,6-Me(3)C(6)H(2)) (1), which contains a pseudooctahedral titanium and two aldehyde carbonyl groups in a cis arrangement. However, in the case of a 1:1 TiCl4-acetone adduct [{(Me(2)CO)TiCl3}(2)(mu-Cl)(2)] (3) the solid-state structure of this acid-base complex is that of a chloro-bridged dimer. Both kinds of structures were suggested for the products [{(PhCOMe)TiCl3}(2)(mu-Cl)(2)] (4) and [cis-(PhCOMe)(2)TiCl4] (5) formed by the reaction of TiCl4 with acetophenone in 1:1 and 1:2 molar ratio. Thioesters behave Like acetone in that they give adducts 8 and 9 with TiCl4, where 9, [{(PhSC(Me)O)TiCl3}(2)(mu-Cl)(2)], exhibits a solid-state dimeric structure Like 3. The bidentate bonding mode of the chiral propionyloxazolidone 12 with TiCl4 was revealed by an X-ray analysis of 13.