PREPARATION AND STRUCTURE OF (ETA(5)-CYCLOPENTADIENYL)(ETA(4)-TETRAPHENYLCYCLOBUTADIENE)COBALT COORDINATED BY 4 CR(CO)3 UNITS AT THE PHENYL RINGS

The reaction of (eta5-cyclopentadienyl)(eta4-tetraphenylcyclobutadiene)cobalt (1) with excess Cr(CO)6 yielded several heterometallic compounds: 2, 3 (3' and 3''), 4 and 5 with, respectively, one, two, three and four phenyl rings complexed with Cr(CO)3 fragment(s). These compounds were characterized by mass, infrared, H-1 and C-13 NMR spectra. The crystal structure of 5 was determined. In 5 the four Cr(CO)3 fragments are on the same side of the CpCo fragment; whereas, the two Cr(CO)3 fragments of 3', the precursor of 5, are pointed in a different direction from the CpCo fragment. The cyclopentadienyl ring shows a static disorder around the axis that passes through the cobalt and the centre of the ring.