Abstract By using [(Cp ″′ Co) 2 tol](Cp ″′= η 5-C 5 H 2 tBu 3, tol= toluene), a new synthesis of the 1, 3-diphosphete complexes [Cp ″′ Co (η 4-P 2 C 2 tBu 2)](1a) and [Cp ″′ Co (η 4-P 2 C 2 iPr 2)](1b) was found, and their reactions with the Lewis acids W (CO) 4 and Cu I halides were investigated. The reaction of 1b with W (CO) 4 (nbd)(nbd= norbornadiene) leads to the complex [(Cp ″′ Co)(μ, η 4: 1-{PCiPr} 2)] 2 W (CO) 4 (2) ...