SYNTHESIS OF TWO NOVEL POLYMERIC HETERONUCLEAR CLUSTER COMPOUNDS, [MoS4Cu6X4(Py)4]n(X = Br, I). CRYSTAL STRUCTURE OF [MoS4Cu6Br4(Py)4]n

The title compounds [MoS4Cu6X4(Py)4]n (1: X = Br; 2: X = I) were obtained by the reaction of [NH4]2 [MoS4], CuX, and [Bu 4 n N]X (X = Br, I) in the solid state and pyridine substitution of the solid state product in acetonitrile. Dark crystals of 1 are tetragonal, space group I 42d with unit cell parameters a = 14.611 (3), c = 15.119 (13) Å; V = 3227.1 Å3; Z = 4, Dcalc = 2.55 g cm−3, R = 0.030 for 586 observed reflections. The X-ray analysis confirms that the structure, which possesses a crystallographic 4 symmetry axis situated at the Mo atom, consists of a tetrahedral MoS4 core enveloped by an octahedral array of six copper atoms, forming an MoS4Cu6 aggregate. Linked by -Cueq-Br-Cueq- bridges, this aggregate connects with its nearest, neighbours and develops a two-dimentional network. The Mo-Cu lengths range from 2.645(1) to 2.668(1) Å.