Chelate Silylene–Silyl Ligand Can Boost Rhodium‐Catalyzed C−H Bond Functionalization Reactions

The first N‐heterocyclic silylene (NHSi)–silane scaffold LSi−R−Si(H)Mes 2 ( 1 ) (L=PhC(N t Bu) 2 ; R=1,12‐xanthendiyl spacer; Mes=2,4,6‐Me 3 C 6 H 2 ) was synthesized and used to form the unique rhodium(III) complex (LSi−R−SiMes 2 )Rh(H)Cl 2 through its reaction with 0.5 molar equivalents of [Rh(coe) 2 Cl] 2 (coe=cyclooctene). An X‐ray diffraction analysis revealed that 2 has a (Si II Si IV )Rh(H)Cl core with three short Rh ⋅⋅⋅ H−C contacts with Me groups of the ligand 1 , which cause a distorted pentagonal bipyramidal coordination of the Rh center. Unexpectedly, the reaction of 2 with t BuONa gives the new bis(silyl)hydridorhodium(III) complex 4 . Due to the strong donor ability of the chelate Si II –Si IV ligand, 2 and 4 can act as highly efficient pre‐catalysts in the Rh‐mediated selective C−H functionalization of 2‐phenylpyridines with C−C unsaturated organic substrates under mild reaction conditions.