SYNTHESIS AND CHARACTERIZATION OF THE MOLYBDOTELLURATES - [M(H2O)(6)](3)CENTER-DOT[TEMO6O24] - M = NI(II) AND CO(II)

Two molybdotellurates [MO(H2O)(6)](3) .[TeMo6O24], with M = Ni (II) an d Co (II) have been synthesised. Both compounds crystallize in the tri gonal space group R-3c, with a = b = 17.906(5), c = 19.458(5) Angstrom , V = 5403(3) Angstrom(3) and a = b = 17.902(4), c = 19.686(3) Angstro m, V = 5448(2) Angstrom(3). The crystal structure of these compounds c onsists of a [TeMo6O24](6-) anion with the TeO6 octahedron at the cent re surrounded by six MoO6 sharing edges. The anion is located around a quo cations M[(H2O)(6)](2+), (M = Ni (II), Co (II)). A hydrogen-bondin g network allows the self assembly of the ionic counterparts. The IR s pectra of both compounds are discussed on the D-3d symmetry of the [Te Mo6O24](6-) anion. The electronic spectra of both compounds were done in solid phase and in solution. The magnetic measurements show that wi th regard to magnetic properties both compounds fulfil the Curie-Weiss law in the range 1.7-300 K and the effective magnetic moments values through this temperature range are 3.10 BM for the nicker complex and 4.57 BM for the cobalt complex. The thermal behaviour of both compound s is also studied.