Sm(ii)reduction chemistry of heteroalkynes: stable adducts, reductive coupling, reductive C–C/C–N bond cleavage and trapping of the tert-butyl fragment with bulky nitriles, phosphaalkynes and isonitriles

Abstract

Reactions of a dimetallated N,N′-dimethyl substituted porphyrinogen Sm(II) complex with a series of t-butyl substituted heteroalkynes affords a diverse range of reactivity. The phosphaalkyne t-BuCP gives a dinuclear Sm(III) P–P reductively coupled complex of (t-BuCPPC-t-Bu)²⁻ featuring a new μ-η²(1,2-C,P) binding mode. In contrast, the nitrile aza analogue t-BuCN forms Sm(II) adducts that undergo reductive C–C bond cleavage at elevated temperatures to afford a trimeric Sm(III) cyanide (μ-CN⁻) complex. The isomeric isonitrile t-BuNC undergoes the related reductive C–N bond cleavage reactivity at milder temperatures, allowing the trapping of the tert-butyl fragment as a Sm(III) η²-iminoacyl (t-BuCN-t-Bu)⁻ complex.