Synthesis of Neutral, Monocationic, and Dicationic Cyclopentadienyl(Isocyanide)Cobalt Complexes

Abstract

The syntheses of C₅H₅Co(CN-t-Bu)I₂ (2) and C₅H₅Co(CNPh)I₂ (3) are reported. On reaction with PMe₃, CNR′ and CH₃CN, these complexes (as well as C₅H₅Co(CNMe)I₂ (1)) are converted to the cationic species [C₅H₅CoI(CNR)PMe₃]⁺, [C₅H₅Co(CNR)(PMe₃)₂]²⁺, [C₅H₅Co(CNR)-(CNR′)PMe₃]²⁺, and [C₅H₅Co (CNR)(CH₃CN)PMe₃]²⁺, which are isolated as the PF₆ salts (4 − 13). The corresponding carbonyl compounds [C₅H₅Co (CO)(CNR)PMe₃]²⁺ can also be prepared but due to the lability of the CO group, analytically pure samples of the PF₆ salts could not be isolated. Reduction of [C₅H₅CoI(CNR)PMe₃]PF₆ with sodium amalgam provides a new route to the uncharged complexes C₅H₅Co(CNR)PMe₃ (15 − 17). The preparation of the bis(isocyanide)cobalt(I) compound C₅H₅Co(CNMe)₂ (18) has similarly been achieved.