Novel stable five-coordinate diorgano cobalt(III) complexes: Formation, structure, and reaction with carbon monoxide

A series of new five-coordinate acyl vinyl cobalt(III) complexes Co{η¹-C(CCPh)CHPh}[C(O)CCO] L₂(L = PMe₃) (6-10) were prepared via formal insertion of diphenylbutadiyne into Co-H function of mer-octahedral hydrido-acyl(phenolato)-cobalt(III) complexes. The complexes are diamagnetic. One square pyramidal structure of complex 6 was confirmed by X-ray diffraction analysis. These complexes are stable in solid state. In solution, six-coordinate acyl vinyl carbonyl cobalt(III) complex 11 is approved through the reaction of complex 7 with CO and the structure of complex 11 was determined by X-ray method.