New Monocyclopentadienyl Complexes of Tantalum with Dithiolate Ligands. Crystal and Molecular Structures of Cp*TaCl₂(SCH₂CH₂)₂S, Cp*TaMe₂(SCH₂CH₂)₂O, Cp*TaMe₂(SCH₂CH₂)₂S, and Cp*Ta(xylylNC(Me)₂CNxylyl)(SCH₂CH₂)₂O (Cp* = η⁵-C₅Me₅)

Cp*TaCl₄ reacts with X(CH₂CH₂SH)₂ in the presence of NEt₃ to yield the corresponding thiolate complexes Cp*TaCl₂(SCH₂CH₂)₂X (X = O (1), S (2)). The 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)₂X (X = O (3), S (4)). They have both been characterized by X-ray diffraction methods. Complex 3 reacts with xylylisocyanide to yield the imine complex Cp*Ta(η²-xylylNCMe₂)(SCH₂CH₂)₂O (6), which undergoes insertion of a second isocyanide molecule to yield an η¹-iminoacyl-containing azatantalacyclobutane compound Cp*Ta(xylylNC(Me)₂CN(xylyl)(SCH₂CH₂)₂O (5), whose structure has been also determined by X-ray diffraction.