Experimental evaluation of the electron donor ability of a gold phosphine fragment in a gold carbene complex.

X-ray analysis of the gold cyclopropyl(methoxy)carbene complex [(P)AuC(OMe)(c-Pr)](+) SbF6(-) [P = P(t-Bu)2o-biphenyl] and comparison to extant protonated cyclopropyl ketones indicates that electron donation from the (P)Au fragment to the electron-deficient C1 atom is similar to that provided by a cyclopropyl group.