Activation of sp³ Carbon−Hydrogen Bonds by Cobalt and Iron Complexes and Subsequent C−C Bond Formation

The sp 3 C−H bond activation induced by CoMe(PMe 3 ) 4 and FeMe 2 (PMe 3 ) 4 was investigated. C(sp 3 )-cyclometalated complexes, based on diphosphinito PCP ligand (Ph 2 POCH 2 ) 2 CH 2, Co{(Ph 2 POCH 2 ) 2 CH}(PMe 3 ) 2 ( 1 ), and Fe{(Ph 2 POCH 2 ) 2 MeC}(H)(PMe 3 ) 2 ( 2 ), were obtained under mild conditions. Iodomethane is oxidatively added to 1, affording Co{(Ph 2 POCH 2 ) 2 CH}(PMe 3 )(Me)(I) ( 3 ). Monocarbonylation of the hydrido-iron complex 2 occurs with substitution of a trimethylphosphine ligand trans to the hydrido ligand, affording Fe{(Ph 2 POCH 2 ) 2 MeC}(H)(CO)(PMe 3 ) ( 4 ). The reaction of 2 with phenylacetylene delivered the demetalated new diphosphine ligand (Ph 2 POCH 2 ) 2 CHCH 3 ( 6 ) and bis(phenylethinyl)iron complex Fe(PhCC) 2 (PMe 3 ) 4 ( 5 ). The new complexes 1 − 4 were characterized by spectroscopic methods and by X-ray diffraction analysis.