Unusual effects of the bulky 1-norbornyl group in cobalt carbonyl chemistry: low-energy structures with agostic hydrogen atoms

Low-energy (nor)Co(CO)n (n = 3, 2) and (nor)2Co2(CO)n (nor = 1-norbornyl; n = 6, 5) structures are found to have agostic hydrogen atoms from a CH2 group adjacent to the Co–C bond forming C–H–Co bridges. In addition, low-energy structures are found with (nor)CO acyl ligands resulting from carbonyl migration.

Tin(IV)-Porphyrin Tetracarbonyl Cobaltate: An Efficient Catalyst for the Carbonylation of Epoxides

Cationic tin(IV) porphyrins with tetracarbonyl cobaltates were synthesized, exhibiting bifunctional catalytic reactivity. The Lewis acidic tin-porphyrin center activated epoxides; concurrently, cobalt carbonyl anions efficiently opened epoxides and delivered carbonyl moieties. Thus, a series of β-lactones with a high synthetic value were obtained. This catalytic system showed excellent efficiency exceeding a turnover number of one thousand with a broad substrate scope. In addition, the presented tin porphyrin-based catalyst exhibited exclusive chemoselectivity to terminal epoxides over internal ones. The selective carbonylation of di-epoxides demonstrated the usefulness of these catalysts in the synthesis of complex molecular structures.

O-Functionalization of a cobalt carbonyl generates a terminal cobalt carbyne

We describe the synthesis of a series of terminally-bound Co-carbonyl complexes, with the most reduced state amenable to O-functionalization to generate a rare example of a late transition metal carbyne.