UC Santa Barbara

Treatment of (IMes)Fe(NTMS2)2 with 4 equiv of methanesulfonyl chloride (MsCl = MeSO2Cl) resulted in a complex reaction sequence involving substitution of two TMS groups for Ms, followed by the unexpected C(sp3)-H bond activation of Ms and subsequent C(sp3)-C(sp3) bond formation to generate the bimetallic Fe complex, [IMesH]2[Cl2Fe(N(TMS)SO2(CH2)2SO2N(TMS))2FeCl2] (1) (IMes = 1,3-bis(2,4,6-trimethylphenyl)-imidazole-2-ylidene; TMS = SiMe3). Extending this C-H activation/C-C bond-forming chemistry to larger alkylsulfonyl chloride chains (i.e., Et and Bu) similarly resulted in C-C coupling, but with decreased chemoselectivity. Detailed mechanistic studies, including using possible intermediate model compounds, were performed in order to elucidate a unifying mechanism for this previously unknown avenue to C(sp3)-C(sp3) bond formation.