Cobalt 13-Diisopropyl-1H-imidazol-2-ylidene Complexes: Synthesis Solid-State Structures and Quantum Chemistry Calculations

摘要

The reaction of (η⁵-C5H5)Co(PPh3)2 (>1) with 1,3-bis(isopropyl)imidazol-2-ylidene (ImⁱPr2, >17) leads to the formation of (η⁵-C5H5)Co(PPh3)(ImⁱPr2) (>5) in 69% yield. N-Heterocyclic carbene >17 also undergoes reaction with (η⁵-C5H5)Co(CO)2 (>9) to give (η⁵-C5H5)Co(ImⁱPr2)(CO) (>6) in 30% yield. The barrier to rotation about the Co−C^carbene bond in >6 has been determined by variable-temperature ¹H NMR spectroscopy (13.6 kcal/mol) and by computation (13.3 kcal/mol). Complex >5 undergoes reaction with PhSSPh to give the paramagnetic thiolato complex (η⁵-C5H₅)Co(ImⁱPr₂)(SPh) (>7), which is oxidized to the metallosulfone complex (η⁵-C₅H₅)Co(ImⁱPr₂)(SO₂Ph) (>8). The solid-state structures of >5−>8 were determined by X-ray crystallography. The structural and dynamic properties of >6, (η⁵-C₅H₅)Co(ImMe₂)(CO) (ImMe₂ = 1,3-dimethylimidazol-2-ylidene), and (η⁵-C₅H₅)Co(ImAr₂)(CO) (ImAr₂ = 1,3-dimesityl-2-ylidene) were examined by quantum chemistry calculations.