Addition of E-H bonds (E = S, N) across the C-alpha=C-beta bond of the allenylidene ligand in [Re{C=C=CPh2}(CO)(2)(triphos)](OSO2CF3) (triphos = MeC(CH2PPh2)(3))

Reaction of the rhenium(I) allenylidene complex [Re{CdCdCPh2}(CO)2(triphos)]OTf (1;triphos ) MeC(CH2PPh2)3, OTf ) -OSO2CF3) with thiophenol, 2-thionaphthol, or allylmercaptan gave selectively the R,â-unsaturated thiocarbene complexes [Re{C(SR)CHdCPh2}(CO)2(triphos)]OTf (R ) Ph (2), R-naphthyl (3), CH2CHdCH2 (4)). A reversible reaction was observed for PhSH in DMSO at 80 °C. Compounds 2 and 3 have been found to react with sodium alkoxides, yielding the kinetic thioallenyl products [Re{C(SR)dCdCPh2}(CO)2(triphos)] (R ) Ph (6a), R-naphthyl (7a)). These equilibrated in room-temperature solution with the thermodynamic thioalkynyl products [Re{CtCC(SR)Ph2}(CO)2(triphos)] (R ) Ph(6b), R-naphthyl (7b)) to give stationary states (6a/6b, 40/60; 7a/7b, 20/80). Deprotonation of the thioallyl complex 4 gave the stable allenyl derivative [Re{C(SCH2CHdCH2)dCdCPh2}(CO)2(triphos)] (8). Ammonia, aniline, and propargylamine each reacted with 1 to give the azoniabutadienyl compounds [Re{C(dNHR)CHdCPh2}(CO)2(triphos)]OTf (R ) H (9), Ph (10), CH2CtCH (11)) via N-H bond addition across the CRdCâ double bond. NMR spectroscopy showed the ç-alkynylammonium complex [Re{CtCCPh2(NH3)}(CO)2(triphos)]OTf (12) to be a transient intermediate along the reaction of 1 with ammonia. Treatment of 10 or 11 with sodium methoxide resulted in the selective deprotonation of the nitrogen atom to give the azabutadienyl compounds [Re{C(dNR)CHdCPh2}(CO)2(triphos)] (R ) Ph (13), CH2CtCH (14)). The molecular structure of the azoniabutadienyl complex 11 was determined by a single-crystal X-ray analysis. The geometry around the rhenium center conforms to a slightly distorted octahedron, with the polyphosphine sitting on a face of the coordination polyhedron. In keeping with the zoniabutadienyl structure, the Re-CR bond length is 2.151(7) Å, and the CR-N distance is 1.300(9) Å.