Molybdotellurates containing the 1-methyl-, 2-methyl- and 4-methyl imidazolium cations

Four molybdotellurates containing the imidatolium, 2-methylimidazolium and 4-methylimidazolium cations have been synthesized and their structures: [2- H-2-methyl-imz](6)[TeMo6O24]. 2H(2)O (2), [2-H-2-methyl-imz](6)[TeMo6O24]. 2(2-H-methyl-imz). 2H(2)O (3) and [4-H-2-methyl-imz](6)[TeMo6O24]. Te(OH)(6 ) (4) determined by X-ray diffraction methods. The protonated organic bases are bonded to the anion in the crystal by hydrogen bonds, except for (4) w here the crystal structure consists of discrete [TeMo6O24](6-) anions and T e(OH)(6) units, both bonded to 4-methylimidazolium cations by hydrogen bond s. The hydrogen bonds were studied as a function of the unit charge of the oxygen atoms of the [TeMo6O24](6-) anion. Distortions of the central octahe dron of polyanions of formula [XMo6O24](n-) (X=Al-III, Mo-VI Te-VI and I-VI I), and polyanions of formula [H6YMo6O24](n-), (Y = Co-II, Cu-II, Zn-II, Cr -III, Rh-III and Pt-IV) are discussed. Mo-95 n.m.r spectroscopy of compound s [1-H-2-methyl-imz](6)[Te-Mo6O24]. Te(OH)(6) (1), (2) and (4) indicates th e existence of an octahedral oxygen atom arrangement around the molybdenum and a pH variation experiment, carried out with compound (1), confirmed the existence of hydrolytic processes of the compounds in aqueous solution. Te -125 n.m.r. studies permitted identification of the Te atom in the [TeMo6O2 4](6-) kernel in all compounds; the presence of two different Te(OH)6 moiet ies in compounds (1) and (4) was also detected. The similarity between the spectra of both compounds could indicate that (1) has the same structural a rrangement as (4). Finally, the thermal behaviour and the thermal stabiliti es of the complexes as a function of the organic cation were studied.