Binuclear platinum-iridium complexes: synthesis, reactivity and luminescence.

The chemistry of the heterobinuclear platinum-iridium complex [PtIr(CO)(3)(mu-dppm)(2)][PF6], 1, dppm = Ph2PCH2PPh2, is described. The reaction of a hydride with 1 gave [HPtIr(CO)(2)(mu-dppm)(2)], by displacement of the carbonyl ligand from platinum, while reaction of 1 with dihydrogen, hydrogen chloride or Ph2MeSiH gave the fluxional complex [PtIrH4(CO)(mu-dppm)(2)][PF6], [PtIrH2Cl2(CO)(mu-dppm)(2)][PF6], or [PtIrH(SiMePh2)(CO)(2)(mu-dppm)(2)][PF6], respectively, by oxidative addition at iridium. Complex 1 reacted, often regioselectively, with several alkynes to give the mu-eta(1),eta(1) bridging alkyne complexes [PtIr(mu-RCCR')(CO)(2)(mu-dppm)(2)][PF6], R = H, R' = Ph, 4-C6H4Me, CO2Me; R = Ph, R' = CO2Me; R = R' = CO2Me. The complex [PtIr(mu-HCC-4-C6H4Me)(CO)(2)(mu-dppm)(2)][PF6] reacted reversibly with CO to give [PtIr(mu-HCC-4-C6H4Me)(CO)(3)(mu-dppm)(2)][PF6] and [PtIr(CO)(3)(mu-dppm)(2)][PF6], 1. With HCl, [PtIr(mu-HCC-4C(6)H(4)Me)(CO)(2)(mu-dppm)(2)][PF6] reacted to give [PtIrHCl(mu-HCC-4-C6H4Me)(CO)(2)(mu-dppm)(2)][PF6], by oxidative addition at iridium, and then the alkenylplatinum derivative [PtIrCl{HC=CH(4-C6H4Me)}(CO)(2)(mu-dppm)(2)][PF6]. [PtIr(mu-HCC-4-C6H4Me)(CO)(2)(mu-dppm)(2)][PF6] reacted slowly with dihydrogen to give 4-MeC6H4CH=CH2 and [PtIrH4(CO)(mu-dppm)(2)][PF6]. The complex [PtIr(mu-HCCPh)(CO)(2)(mu-dppm)(2)][PF6] is intensely luminescent in solution at room temperature, with features characteristic of a d(8)-d(8) face-to-face complex.