ARENE COMPLEXES OF TITANIUM AND ZIRCONIUM - SYNTHESIS AND STRUCTURE

The synthetic methods and main structural types of arene complexes of titanium and zirconium in oxidation states from IV to 0 are reviewed. The synthetic possibilities Of MX4/M'/AlX3/arene systems are discussed in some detail. In the Zr-Cl systems, the charge of triangular cluster cations [(Arene)3Zr3Cl6]n+ (2 or 3) controls the Zr-Zr distances. In general, the stability of arene complexes increases for the more substituted arene ligands C6H6-mMem and from the iodo to chloro derivatives, the M-C distances being independent of X within the known structural types. Distinctions between structural chemistry of titanium and zirconium arene complexes are determined by the different sizes of their atoms resulting in different coordination possibilities, and the most stable 16- and 18-electron valence configurations, respectively.