A novel one-dimensional (1-D) mixed-valent thioarsenate (III, V), {[Mn(phen)](3)((AsS4)-S-V)((AsS3)-S-III)}(n)center dot nH(2)O (1), with a noncentrosymmetric (NCS) polar packing arrangement has been obtained under solvothermal conditions. The noncondensed ((AsS3)-S-III)(3-) anion in 1 is stabilized by coordinating to [Mn-II(phen)](2+) complex cations and exhibits an unprecedented mu(3)-1,2 kappa S:2,3 kappa S':3 kappa S '' linkage mode. Compound 1 represents the first example of the stabilization of noncondensed (MQ(3))(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 ((AsS4)-S-V)(3-) tetrahedron and the noncondensed ((AsS3)-S-III)(3-) pyramid in a single compound. Of particular interest, compound 1 is also an antiferromagnet with T-N = 31 K, and exhibits photoluminescence (PL) with a maximum emission at about 438 nm and a second harmonic generation (SHG) response.