Octahedral cyanohydroxo cluster complex trans-[Re6Se8(CN)4(OH)2]4−: Synthesis, crystal structure, and properties

A hexarhenium cyanohydroxo anionic cluster complex [Re6Se8(CN)4(OH)2]4− was synthesized for the first time starting from [Re6Se8(OH)6]4−, which was crystallized as a salt of the composition Cs2.75K1.25[Re6Se8(CN)4(OH)2]·H2O (1). The reaction of the complex with Cu2+ in an aqueous ammonia or methylamine solutions afforded [Cu(NH3)5]2[Re6Se8(CN)4(OH)2]·8H2O (2) or [{Cu(CH3NH2)4}2Re6Se8(CN)4(OH)2] (3), respectively. All of these three compounds were characterized by a single-crystal X-ray diffraction method. Compound 1 is crystallized in the tetragonal space group I4/m with eight formula units per cell (a = b = 17.4823(14) Å, c = 19.430(2) Å, V = 5938.3(10) Å3); compound 2 is crystallized in the monoclinic space group P21/n with two formula units per cell (a = 12.1845(13) Å, b = 8.6554(9) Å, c = 19.2568(19) Å, β = 91.081(2)°, V = 2030.5(4) Å3); compound 3 is crystallized in the orthorhombic space group Cmcm with four formula units per cell (a = 19.816(4) Å, b = 14.611(3) Å, c = 13.751(3) Å, V = 3981.2(13) Å3). The luminescence properties of 1 were studied in both aqueous solution and solid state. In addition, the electronic structure of [Re6Se8(CN)4(OH)2]4− was elucidated by DFT calculations.