CYCLOOCTATETRAENYL COMPLEXES OF EARLY TRANSITION-METALS AND LANTHANOIDS .2. NEW HALF-SANDWICH CYCLOOCTATETRAENYL COMPLEXES OF YTTRIUM

Dimeric [(COT)Y(mu-O3SCF3)(THF)]2 (1) is introduced as a versatile starting material for new monocyclooctatetraenyl complexes of yttrium (COT = cyclooctatetraenyl(2-)). Treatment of 1 with pyrazolylborate anions yields the monomeric half-sandwich complexes (COT)Y(HBpz3) (2) and (COT)Y[HB(3,5-Me2pz)3] (3). The yttrium benzamidinates (COT)Y[MeOC6H4C(NSiMe3)2]THF (4) and (COT)Y[CF3C6H4C(NSiMe3)2](THF) (5) are prepared similarly. An yttrium phosphazene derivative, (COT)Y[Ph2P(NSiMe3)2](THF) (6) is obtained by treating 1 with Li[Ph2P(NSiMe3)2]. All new organoyttrium complexes have been fully characterized by elemental analyses and spectroscopic methods including Y-89 NMR spectrocopy.