The synthesis and structural characterization of bis(mercaptoimidazolyl)hydroborato complexes of lithium, thallium and zinc

Abstract

Bidentate [S₂]-donor bis(mercaptoimidazolyl) ligands, [Bm^Me]⁻ and [Bm^Mes]⁻, have been synthesized by reaction of [BH₄]⁻ with 2-mercapto-1-methylimidazole and 2-mercapto-1-mesitylimidazole, respectively. Subsequent treatment with ZnX₂ (X = Me, I, NO₃) yields a series of 1∶1 [Bm^R]ZnX complexes, namely [Bm^Me]ZnMe, [Bm^Me]ZnI and [Bm^Mes]Zn(NO₃), each of which possesses 3-center–2-electron [Zn⋯H–B] interactions. The homoleptic complex, [Bm^Me]₂Zn, may be obtained by a redistribution reaction of [Bm^Me]ZnMe in CHCl₃, and possesses a tetrahedral zinc center which is devoid of a 3-center–2-electron [Zn⋯H–B] interaction.