Redox properties of (RC 2 R')Co 2 (CO) 6‐ n L n and reactivity of (RC 2 R')Co 2 (CO) 6‐ n L n towards PPh 3 [LPPh 3 , P(OEt) 3 ]

Cyclic voltammetric studies of clusters (C 5 H 5 ‐C 2 C 6 H 4 ‐R‐ p )Co 2 (CO)6‐n L n [ n =0,2; L=PPh 3 , P(OEt) 3 ] and (RCH 2 C) 2 Co 2 (CO 4 ) (PPh 3 ) 2 on Pt electrode are described. The primary reduction (0 / −1) and oxidation (+ 1 / 0) steps are considered as a mono‐electron process for all clusters. For the clusters (C 5 H 5 C 2 C 6 H 4 ‐R‐ p )Co 2 (CO) 6 , a good linear relation between reduction potential E p red and Hammett constant σ p of R in the clusters is found. For the clusters (RC 2 R')Co 2 (CO) 4 L 2 , their radical anions are extremely unstable at room temperature and fragment into a series of mononuclear species, one of which is (RC 2 R')Co(CO) 2 PPh 3 . The reaction of radical anions of (RC 2 R')Co 2 (CO) 6–n (PPh 3 ) n ( n =0,2) with PPh 3 also produces mononuclear species (RC 2 R')Co(CO) 2 PPh 3 which has been detected by means of cyclic voltammetry and ESR. The influence of R on redox properties of clusters is discussed.