Synthesis and Characterization of Substituted Half-Sandwich Cobalt Complexes

Abstract

The substituted cyclopentadienyl dicarbonyl cobalt complexes (q⁵-C₅H₄R)Co(CO)₂ 1–4 [1, R = -CO₂CH₂C₆H₅; 2, R = -CO₂C(CH₃)[dbnd]CH₂; 3, R = -CO₂CH₂CH[dbnd]CH₂; 4, R = -CH₂CO₂CH₂CH[dbnd]CH₂] were prepared from the corresponding substituted cyclopentadienyl sodium salts, octawbonyl dicobalt and iodine. Compounds 1 and 3 reacted with iodine to afford the monocarbonyl diiodide derivatives (n⁵-C₅H₄R)Co(CO)I₂ 5 (R = -CO₂CH₂C₆H₅) and 8 (R = -CO₂CH₂CH[dbnd]CH₂). Compounds 5 and 8 reacted further with triphenylphosphine to give the monophosphine derivatives (n⁵-C₅H₄R)Co(PPh₃)I₂ 6 (R = -CO₂CH₂C₆C₅) and 9 (R = -CO₂CH₂CH[dbnd]CH₂) in high yields. The diphosphine compound 7 ((n⁵-C₅H₄R)Co(PPh₃)₂, R = -CO₂CH₂C₆H₅) was synthesized by the reaction of NaC₅H₂CO₂CH₂C₆H₅ with ClCo(PPh₃)₃. Compounds 1–9 were isolated and hlly characterized by analytical and spectroscopic methods.