Rare examples of hybrid chalcogenoarsenate(iii) incorporating trivalent vanadium complexes

Abstract

A series of new hybrid vanadium chalcogenoarsenates(III) [V^III(en)₂As^IIIS₃] (1, en = ethylenediamine), [V^III(dap)₂As^IIISe₃] (2, dap = 1,2-diaminopropane), [V^III(teta)As^IIIQ₃] {Q = S (3) and Se (4), teta = triethylene-tetramine}, and [V^III₂(en)₆(μ₂-O)][As₂Se₅] (5) were solvothermally prepared and structurally characterized. The trigonal-pyramidal [As^IIIQ₃]³⁻ anions in 1–4 act as η²-As^IIIQ₃ chelating ligands to the unsaturated trivalent vanadium complex cations [V^III(en/dap)₂]³⁺/[V^III(teta)]³⁺, resulting in neutral molecules. 5 consists of a discrete saddle-like selenidoarsenate [As₂Se₅]⁴⁻ anion built up from corner-sharing [AsSe₃]³⁻ trigonal pyramids and the dinuclear trivalent vanadium complex cation [V^III₂(en)₆(μ₂-O)]⁴⁻ constructed through two [V^III(en)₃]³⁺ units bridged via one μ₂-O group. The [V^III(en)₃]³⁺ unit contains two bidentate chelating en ligands and one monodentate en ligand, and offers a rare example of an en molecule as a monodentate ligand, because the en molecule usually exhibits the bidentate chelating coordinated mode. Emphatically, although some chalcogenoarsenates combined with transition metal complexes were isolated from chelating organic amine systems by a solvothermal reaction, no trivalent vanadium complex cations are involved in combination with the chalcogenoarsenates in this synthetic method to date. Therefore, 1–5 represent rare examples of hybrid chalcogenoarsenate(III) incorporating trivalent vanadium complexes. The absorption edges of 1–5 are in the energy range of 1.43–1.62 eV, and -they exhibit distinctive photocurrent response and photoconductive properties upon visible-light illumination.