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

• Published in: Chemistry : a European journal Vol. 24; no. 55; pp. 14608 - 14612
• Main Authors: Mo, Zhenbo, Kostenko, Arseni, Zhou, Yu‐Peng, Yao, Shenglai, Driess, Matthias
• Format: Journal Article
• Language: English
• Published: WEINHEIM Wiley 01.10.2018; Wiley Subscription Services, Inc
• Subjects: agostic complexes; alkenylation; atoms in molecules; Catalysts; Chelates; Chemical reactions; Chemistry; Chemistry, Multidisciplinary; density functional calculations; Ligands; N-heterocyclic silylenes; Physical Sciences; Rhodium; Science & Technology; Substrates; X-ray diffraction; ALKANE COMPLEXES; ACTIVATION; (9,9-DIMETHYLXANTHENE-4,5-DIYL)BIS(DIMETHYLSILYL); AGOSTIC INTERACTIONS; N-heterocyclic silylenes; N-H; RUTHENIUM(II) COMPLEX; CARBON-HYDROGEN BONDS; agostic complexes; MOLECULES; alkenylation; density functional calculations; atoms in molecules; INTERMEDIATE; METAL-COMPLEXES
• ISSN: 0947-6539; 1521-3765; 1521-3765
• DOI: 10.1002/chem.201803089

The first N‐heterocyclic silylene (NHSi)–silane scaffold LSi−R−Si(H)Mes2 (1) (L=PhC(NtBu)2; R=1,12‐xanthendiyl spacer; Mes=2,4,6‐Me3C6H2) was synthesized and used to form the unique rhodium(III) complex (LSi−R−SiMes2)Rh(H)Cl 2 through its reaction with 0.5 molar equivalents of [Rh(coe)2Cl]2 (coe=cyclooctene). An X‐ray diffraction analysis revealed that 2 has a (SiIISiIV)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 tBuONa gives the new bis(silyl)hydridorhodium(III) complex 4. Due to the strong donor ability of the chelate SiII–SiIV 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. Agostic complexes: A pentagonal‐bipyramidal rhodium(III) complex featuring one agostic and two anagostic interactions with a new SiII–SiIV ligand has been synthesized. It can be used as pre‐catalyst for alkenylation and alkylation of C−H bonds with high catalytic efficiency under mild reaction conditions (see scheme).