Stabilization of Noncondensed (As^IIIS₃)^3– Anions by Coordinating to [Mn^II(phen)]²⁺ Complex Cations: a Mixed-Valent Thioarsenate (III, V) {[Mn(phen)]₃(As^VS₄)(As^IIIS₃)}_<i>n</i>·<i>

A novel one-dimensional (1-D) mixed-valent thioarsenate (III, V), {[Mn(phen)]3(AsVS4)(AsIIIS3)}n·nH2O (1), with a noncentrosymmetric (NCS) polar packing arrangement has been obtained under solvothermal conditions. The noncondensed (AsIIIS3)3– anion in 1 is stabilized by coordinating to [MnII(phen)]2+ complex cations and exhibits an unprecedented μ3-1,2κS:2,3κS′:3κS′′ linkage mode. Compound 1 represents the first example of the stabilization of noncondensed (MQ3)3– (M = As, Sb; Q = S, Se) species only in the coordination of TM(II) complex cations (TM = transition-metal) and the first observation of the coexistence of the (AsVS4)3– tetrahedron and the noncondensed (AsIIIS3)3– pyramid in a single compound. Of particular interest, compound 1 is also an antiferromagnet with TN = 31 K, and exhibits photoluminescence (PL) with a maximum emission at about 438 nm and a second harmonic generation (SHG) response.