METHYLATION OF (PENTAMETHYLCYCLOPENTADIENYL)TRICHLORO(DIPHENYLDIMETHYLENEPHOSPHORANYL-C,C)TANTALUM(V) - CRYSTAL-STRUCTURES OF [TACP-ASTERISK-CL3((CH2)2PPH2)] AND [TACP-ASTERISK-ME2((CH)(CH2)PPH2)]

The X-ray diffraction study of [TaCp*Cl3{(CH2)2PPh2}] confirms its monomeric structure, previously proposed on the basis of its NMR behaviour. Alkylation of this compound leads to the isolation of its trimethyl derivative, along with a residue which contains minor amounts of the monomethyl complex. The pyrolysis of the trimethyl complex affords [TaCp*Me2{(CH)(CH2)PPh2}] whose crystal structure has been determined by X-ray diffraction methods.