Thioarsenate anions acting as ligands: Solvothermal syntheses, crystal structures and characterizations of transition metal complexes of thioarsenate and polyethyleneamine ligands

Abstract

New members of transition metal complexes with thioarsenate ligands, [Co(peha)][Co(As3S3)2] (peha=pentaethylenehexamine) (1), [Co(trien)(AsS3)] (2), [Cr(trien)(AsS3)] (trien=triethylenetetramine) (3) and [Cr(en)2(AsS3)] (en=ethylenediamine) (4) were prepared by solvothermal reactions in polyamines. In 1, two As3S3 units coordinate to a Co2+ ion with both As- and S-donor atoms in the 1κ2As1,As2:1κS1-As3S3 coordination mode to form the novel [Co(As3S3)2]2− anionic cluster, in which CoAs2, CoAs2S2, and CoAs3S2 rings are formed. Another Co2+ ion is coordinated by a hexadentate peha ligand to form a octahedral [Co(peha)]2+ complex cation. Both Co3+ and Cr3+ ions are coordinated by a tetradentate trien ligand and a bidentate chelating ligand [AsS3]3−, and neutral complexes [Co(trien)(AsS3)] (2) and [Cr(trien)(AsS3)] (3) are formed. The Cr3+ is coordinated by two en ligands and a bidentate chelating ligand [AsS3]3− to form neutral complex Cr(en)2(AsS3)] (4). Complexes 2–4 represent the first examples of TM–thioarsenate complexes with polyethyleneamine coligands. Compounds 1–4 are potential semiconductors with narrow well-defined optical band gaps in the range of 1.45–1.74eV. Thermal properties of 1–4 were investigated via thermogravimetric analyses.