Ruthenium and osmium complexes of dihydroperimidine-based N-heterocyclic carbene pincer ligands

摘要

The reactions of N,N'-bis(phosphinomethyl) dihydroperimidine pro-ligands H2C(NCH2PR2)(2)C10H6 (R = Cy 1a, R = Ph 1b) with [RuCl2(PPh3)(3)] give markedly different products. Chelate-assisted double C-H activation in the former affords the perimidinylidene-based N-heterocyclic carbene (per-NHC) pincer complex [RuCl2(OC4H8){kappa(3)-P,C,P'-C(NCH2PCy2)(2)C10H6}] (2), while the latter reaction provides the asymmetric PNP-coordinated complex [RuCl2(PPh3){kappa(3)-P,N,P'-CH2(NCH2PCy2)(2)C10H6] (3), in which no C-H activation has occurred. Subsequent reactions of the per-NHC complex 2 with carbon monoxide and mesityl isocyanide readily displaced the labile THF ligand to afford the complexes [RuCl2(CA){kappa(3)-P,C,P'-C(NCH2PCy2)(2)C10H6}] (A = O 4, A = NC6H2Me3 5). Double C-H activation of 1a and 1b was significantly more facile on reaction with [OsCl2(PPh3)(3)], providing the per-NHC complexes [OsHCl(PPh3){kappa(3)-P,C,P'-C(NCH2PR2)(2)C10H6}] (R = Cy 7a, R = Ph 7b, respectively), each as two isomers. The reactions of 1b with [Ru-2(mu-Cl)(2)Cl-2(mu-C6H3Me3)(2)] or [AuCl(THT)] (THT = tetrahydrothiophene) provide the bimetallic complexes [Ru-2{mu-H2C(NCH2PPh2)(2)C10H6}Cl-4(eta-C6H3Me3)(2)] (8) and [Au-2{mu-H2C(NCH2PPh2)(2)C10H6}Cl-2] (9) without C-H activation occurring.