Abstract Reactions of Rh(ClO 4 )(CO)(PPh 3 ) 2 with dicyano olefins, cis -NCCHCH-CH 2 CH 2 CN ( c -DC1B), rans -NCCHCHCH 2 CH 2 CN ( t -DC1B), trans -NCCH 2 CHCHCH 2 CN ( t -DC2B), and NCCH 2 CH 2 CH 2 CN (DCB) produce the binuclear dicationic rhodium(I) complexes, [(CO)(PPh 3 ) 2 RhNCACNRh-(PPh 3 ) 2 (CO)](ClO 4 ) 2 (NCACN = c -DC1B 1 ), t -DC1B ( 2 ), t -DC2B ( 3 ), DCB ( 4 ). Complexes 1 and 2 are catalytically active for the hydrognation of c -DC1B and t -DC1B, respectively, to give DCB, while complex 3 catalyze the isomerization of t -DC2B to give c -DC1B and t -DC1B, and the hydrogenation of t -DC2B to DCB at 100°C.