Structurally versatile phosphine and amine donors constructed from N-heterocyclic olefin units

Abstract

A general strategy for the synthesis of hindered N- and P-based donors is presented whereby the strongly electron releasing N-heterocyclic olefin (NHO) unit, IPrCH–, (IPrCH– = [(HCNDipp)₂CCH]⁻; Dipp = 3,6-ⁱPr₂C₆H₂) is linked to terminally bound phosphine and amine donors. Preliminary coordination chemistry is presented involving phosphine (IPrCH)PR₂ (R = ⁱPr and Ph) and amine (IPrCH)NMe₂ ligands and the Lewis acids BH₃ and AuCl. Interestingly, (IPrCH)NMe₂ binds AuCl through an exocyclic olefin unit, while the softer phosphorus centers in (IPrCH)PR₂ coordinate to yield Au–P linkages; thus the reported NHO-based ligands exhibit tunable binding modes to metals.