Ligand substitution reaction in the parent cluster (μ 3-FcCHC)FeCo 2(CO) 9 and structural characterization of its CO substituted derivatives

Abstract

The new mixed metal carbonyl clusters (μ 3-FcCHC)FeCo 2(CO) 7dppm (Fc = C 5H 5FeC 5H 4, ferrocenyl; dppm = Ph 2PCH 2PPh 2) ( 1), (μ 3-FcCHC)FeCo 2(CO) 8L [L = PPh 3 ( 2); AsPh 3 ( 3)] and (μ-FcC CH)Co 2(CO) 5PPh 3 ( 4) have been synthesized by facile substituted reactions. The crystal and molecular structures of 1, 2 and 3 have been determined by single crystal X-ray analysis; the ligand dppm replaces two equatorial carbonyls from two Co(CO) 3 groups in the FeCo 2 core, and the ligands PPh 3 and AsPh 3 replace one equatorial carbonyl from a Co(CO) 3 group. The new compounds were characterized by IR, 1H, 13C, 31P (for 1, 2) NMR and MS. The electrochemical properties for 1, 2, 3 and 5 were investigated and the results show that the replacement of CO alters the electron density on the cluster core FeCo 2 leading to a variety of interactions between FeCo 2 and the apical FcCHC, and making the Fe of the ligand FcCHC in clusters 1, 2 and 3 turn into a redox center.