Amido Ca(ii) complexes supported by Schiff base ligands for catalytic cross-dehydrogenative coupling of amines with silanes?

Dalton Transactions Pub Date: 2018-05-24 DOI: 10.1039/C8DT01130C

Abstract

A series of amido Ca complexes LCa[N(SiMe3)2](THF) (1–4) coordinated by Schiff base ligands L1–4 were synthesized via an amine elimination reaction between proligands L1–4H and a bisamido complex Ca[N(SiMe3)2]2(THF)2 in good yield. Unlike Ca[N(SiMe3)2]2(THF)2, the reactions of M[N(SiMe3)2]2(THF)2 (M = Yb, Sm) with proligands L1–4H do not lead to the formation of the target Ln(II) amido complexes. The reaction of Yb[N(SiMe3)2]2(THF)2 with L1H is accompanied by intramolecular C–H bond activation of a quinoline ring and results in the formation of complex 6 coordinated by a new trianionic [NNNNOO] ligand. The reactions of amido complexes 1 and 4 with PhSiH3 do not allow for preparing the related hydrides but afford homoleptic bis(phenolate) complexes 5 and 7 due to a ligand redistribution reaction. Amido complexes 1–4 were evaluated as precatalysts for cross-dehydrogenative coupling of silanes (PhSiH3, Ph(Me)SiH2, and Ph3SiH) and aliphatic, aromatic and cyclic amines (RNH2 and R2NH).

Graphical abstract: Amido Ca(ii) complexes supported by Schiff base ligands for catalytic cross-dehydrogenative coupling of amines with silanes
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