METALLACYCLOBUTENES VIA ETA-2-CYCLOPROPENE COMPLEXES OF TITANOCENE AND ZIRCONOCENE

(eta-2-Cyclopropene)(trimethylposphane) complexes of titanocene (4, 5) and zirconocene (8) are obtained in good yields by the reaction of 1,2-diphenylcyclopropene (2) or 4,8-dioxaspiro[2.5]oct-1-ene (3) with bis(trimethylphosphane)titanocene (1) and (1-butene)(trimethylphosphane)zirconocene (7), respectively. In solution the new complexes 4 and 8 rearrange smoothly above room temperature to give the metallacyclobutene derivatives 6 and 9. All new compounds were characterized by spectroscopic methods (P-31, H-1, C-13 NMR), and the crystal structure of 9 was determined by an X-ray analysis.