Pentachloro- and pentabromo-titanate(IV) ions
Abstract
The reactions between titanium(IV) chloride and tetra-alkylammonium chlorides and between titanium(IV) bromide and tetra-alkylammonium bromides, in solution in dichloromethane, have been studied by Raman and i.r. spectroscopy. The five-co-ordinate ions [TiCl5]– and [TiBr5]– have been clearly identified for the first time. These ions and the other singly charged species [Ti2Cl9]– and [Ti2Br9]– are the only anions detected by Raman spectroscopy in the dichloromethane solutions. The preparations of the tetrabutylammonium salts [Bu4N][TiCl5] and [Bu4N][TiBr5] and of tetraphenylarsonium pentachlorotitanate are described, but the corresponding salts of the smaller tetraethyl- and tetrapropyl-ammonium cations are shown to be [Et4N]2[Ti2Cl10], [Et4N]2[Ti2Br10], and [Pr4N]2[Ti2Cl10] with binuclear halogen-bridged anions.