Rare examples of hybrid chalcogenoarsenate(III) incorporating trivalent vanadium complexes.

ABSTRACT

A series of new hybrid vanadium chalcogenoarsenates(III) [VIII(en)2AsIIIS3] (1, en = ethylenediamine), [VIII(dap)2AsIIISe3] (2, dap = 1,2-diaminopropane), [VIII(teta)AsIIIQ3] {Q = S (3) and Se (4), teta = triethylene-tetramine}, and [VIII2(en)6(µ2-O)][As2Se5] (5) were solvothermally prepared and structurally characterized. The trigonal-pyramidal [AsIIIQ3]3- anions in 1-4 act as η2-AsIIIQ3 chelating ligands to the unsaturated trivalent vanadium complex cations [VIII(en/dap)2]3+/[VIII(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 [VIII2(en)6(µ2-O)]4- constructed through two [VIII(en)3]3+ units bridged via one µ2-O group. The [VIII(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.