Mixed-valent selenidoantimonates(III,V) with transition-metal complexes as counterions:: Solvothermal syntheses and characterization of [M(dien)2]2Sb4Se9 (M = Mn, Fe), [Co(dien)2]2Sb2Se6, and [Ni(dien)2]2Sb2Se5

Novel selenidoantimonate compounds [M(dien)(2)](2)Sb4Se9 [M = Mn (1), Fe (2)], [Co(dien)(2)](2)Sb2Se6 (3), and [Ni- (dien)(2)](2)Sb2Se5 (4) (dien = diethylenetriamine) were solvothermally synthesized and characterized. The unique features of compounds 1 - 3 are the mixed-valent anionic structures constructed by the (SbSe3)-Se-III trigonal pyramid and (SbSe4)-Se-V tetrahedron. Three (SbSe3)-Se-III pyramids share common corners, forming a heterocyclic Sb3Se6 moiety, and the Sb3Se6 moieties are further connected with (SbSe4)-Se-V tetrahedra to form the novel one-dimensional [Sb4Se94-](n) anionic chain in 1 and 2. The discrete [Sb2Se6](4-) anion in 3 is formed by an (SbSe3)-Se-III trigonal pyramid and an (SbSe4)-Se-V tetrahedron sharing a common corner. The [Sb2Se5](4-) anion in 4 is composed of two (SbSe3)-Se-III trigonal pyramids connected in the same manner as the [Sb2Se6](4-) anion. The mixed-valent [Sb4Se94-](n) and [Sb2Se6](4-) anions were not observed before. The synthesis and solid-state structural studies of the title compounds show that the transition-metal complexes exhibit different structure-directing effects on the formation of selenidoantimonates in dien. Extensive N-H center dot center dot center dot Se hydrogen bonds are observed between cations and anions in compounds 1 - 4, resulting in three-dimensional network structures. Optical and thermal properties of the compounds are reported.