A potentially bidentate cobalt-containing phosphine ligand, [(η 5 -C 5 H 5 )Co(η 4 -1,3-(PPh 2 ) 2 C 4 Ph 2 )] (trans-1), was prepared from the reaction between PhCCPPh 2 and CpCo(PPh 3 ) 2 obtained in situ from CoCl(PPh 3 ) 3 and NaCp. The cobaltacycle [(η 5 -C 5 H 5 )(PPh 3 )Co(2,5-(PPh 2 ) 2 C 4 H 2 )] (2) was prepared from the reaction of CpCo(PPh 3 ) 2 with HCCPPh 2 . An oxidized product [(η 5 -C 5 H 5 )(PPh 3 )Co(2,5-(P(O)Ph 2 ) 2 C 4 H 2 )] (4), was obtained upon the attempted isolation of 2 using CTLC. Both 2 and 4 failed to produce [(η 5 -C 5 H 5 )Co(η 4 -1,2-(PPh 2 ) 2 C 4 H 2 )] or its oxidized analog, respectively, upon thermal activation. The performance of phosphine 1 in the Suzuki coupling of several aryl chlorides with phenylboronic acid in the presence of Pd(OAc) 2 was evaluated.