New monocyclopentadienyl complexes of tantalum with dithiolate ligands. Crystal and molecular structures of Cp*TaCl2(SCH2CH2)(2)S, Cp*TaMe2(SCH2CH2)(2)O, Cp*TaMe2(SCH2CH2)(2)S, and Cp*Ta(xylylNC(Me)(2)C=Nxylyl)(SCH2CH2)(2)O (Cp* = eta(5)-C5Me5)

Cp*TaCl4 reacts with X(CH2CH2SH)(2) in the presence of NEt3 to yield the co rresponding thiolate complexes Cp*TaCl2(SCH2CH2)(2)X (X = O (1), S (2)). Th e crystal structure of complex 2 has been determined by X-ray diffraction. The tantalum methyl complex Cp*TaMe4 reacts with X(CH2CH2SH)(2), rendering Cp*TaMe2(SCH2CH2)(2)X (X = O (3), S (4)). They have both been characterized by X-ray diffraction methods. Complex 3 reacts with xylylisocyanide to yie ld the imine complex Cp*Ta(eta (2)-xylylNCMe(2))(SCH2CH2)(2)O (6), which un dergoes insertion Of a second is ocyanide molecule to yield an eta (1)-imin oacyl-containing azatantalacyclobutane compound Cp*Ta(xylylNC(Me)(2)C=N(xyl yl)(SCH2CH2)(2)O (5), whose structure has been also determined by X-ray dif fraction.