Coordination chemistry of phosphinocarbynes: phosphorus vs. carbyne site selectivity.

The phosphinocarbyne complex [W([triple bond, length as m-dash]CPPh2)(CO)2(Tp*)] (1: Tp* = hydrotris(dimethylpyrazolyl)borate) coordinates transition metal fragments via the phosphine to form bimetallic species [W{[triple bond, length as m-dash]CPPh2RhCl2(Cp*)}(CO)2(Tp*)] (2) and [W([triple bond, length as m-dash]CPPh2AuCl)(CO)2(Tp*)] (3). Appropriately tailored sterics allow for complexation of a second equivalent of AuCl to afford the trimetallic complex [W{η2-C(AuCl)PPh2AuCl}(CO)2(Tp*)] (4), containing an Au-W-C dimetallacyclopropene connectivity. Similarly, AuCl binds to the carbyne linkage in [W{[triple bond, length as m-dash]CP([double bond, length as m-dash]S)Ph2}(CO)2(Tp*)], yielding [W{η2-C(AuCl)P([double bond, length as m-dash]S)Ph2}(CO)2(Tp*)] (5). In the case of auration of the ditungsten species [W2(μ-C2PPh)(CO)4(Tp*)2] (6), variation in the stoichiometry leads to trimetallic [W2(μ-C2PPhAuCl)(CO)4(Tp*)2] (7) and pentametallic [W2{μ-(η2-CAuCl)2PPhAuCl}(CO)4(Tp*)2] (8) complexes, via a proposed tetrametallic intermediate [W2{μ-(η2-CAuCl)2PPh}(CO)4(Tp*)2], the site selectivity being dictated by aurophilic interactions.