Reactions of [Cu(X)(BPEP-Ph)] (X = PF6, SbF6) with silyl compounds. Cooperative bond activation involving non-coordinating anions

Abstract

Bond activation of silyl compounds, assisted by the cooperative action of non-coordinating anions, is achieved using Cu(I) complexes coordinated with a PNP-pincer type phosphaalkene ligand, [Cu(X)(BPEP-Ph)] (X = PF₆ (1a), SbF₆ (1b); BPEP-Ph = 2,6-bis[1-phenyl-2-(2,4,6-tri-tert-butylphenyl)-2-phosphaethenyl]pyridine). Complexes 1a and 1b react with Me₃SiCN to form Me₃SiF and Cu(I) cyanide complexes of the formula [Cu(CN-EF₅)(BPEP-Ph)] (E = P (2a), Sb (2b)), in which the CN ligand is associated with the EF₅ group arising from EF₆⁻. Formation of the intermediary isonitrile complex [Cu(CNSiMe₃)(BPEP-Ph)]⁺SbF₆⁻ (3b) is confirmed by its isolation. Thus, a two-step reaction process involving coordination of Me₃SiCN, followed by nucleophilic attack of SbF₆⁻ on the silicon atom of 3b is established for the conversion of 1b to 2b. Complex 1b cleaves the H–Si bond of PhMe₂SiH as well. The isolation and structural identification of [Cu(BPEP-Ph)]⁺BAr^F₄⁻ (1c) (BAr^F₄ = B{3,5-(CF₃)₂C₆H₃}₄) as a rare example of a T-shaped, three-coordinated Cu(I) complex is reported.