Five examples of two-coordinate copper(I) fluoride complexes stabilized by five-, six-, and sevenmembered-ring N-heterocyclic carbenes or a cyclic (alkyl)-(amino)carbene have been prepared, structurally characterized, and employed in the catalytic allylation of octanal. The very bulky trityl-based carbene ITr affords the most active catalytic system. Mechanistic studies have led to the isolation of (ITr)Cu(CH 2 CHCH 2 ) and [{(6-Mes)Cu} 2 (μ-OEt)][SiF 5 ], which along with the fluorosilane (EtO) 3 SiF are of relevance to the catalytic cycle.

The ability of phosphacyclohexadienyl anions [Li(1-R-PC 5 Ph 3 H 2 )] [R = Me (1 a), nBu (1 b), tBu (1 c), Ph (1 d) and CH 2 SiMe 3 (1 e)] to initiate hydrofunctionalisation reactions was investigated and compared with simple, commercially available compounds, such as LiOtBu, KOtBu and nBuLi. All compounds are expedient catalysts for the hydroboration of a wide scope of substrates, ranging from aldehydes to imines and esters. In the hydroboration of carbon dioxide, however, only our system was observed to efficiently produce the desired methanol equivalents.