SYNTHESIS, CRYSTAL-STRUCTURE, AND VIBRATIONAL AND ELECTRON-SPIN-RESONANCE STUDY OF TERT-BUTYLAMMONIUM CHROMOHEXAMOLYBDATES, [(CH3)(3)CNH3](N)-[H9-NCRMO6O24]CENTER-DOT-MH(2)O (N = 2, M = 2, N = 3, M = 8) - EFFECTS OF DEGREES OF PROTONATION AND HYDRATION

Two tert-butylammonium chromohexamolybdates (VI) with the formula [(CH 3)(3)CNH3](3)[H6CrMo6O24]. 8H(2)O (1) and [(CH3)(3)CNH3](2)[H7CrMo6O24 ]. 2H(2)O (2), have been synthesised. Crystal data are as follows. Com pound 1: space group P2(1)/n, a = 14.421(2), b = 11.263(6), c = 28.954 (3) Angstrom beta = 99.70 (1)degrees, V = 4635(2) Angstrom(3), Z = 4, R(F-o) = 0.053 and R-w(F-o) = 0.057; compound 2: space group C2/c, a = 27.923(3), b = 11.191(2), c = 11.783(3) Angstrom, beta = 102.15(2)deg rees, V = 3600(1) Angstrom(3), Z = 4, R(F-o) = 0.078 and R-w(F-o) = 0. 077. A structure in layers showing the existence of hydrophobic layers is clearly seen for both compounds. The structures are stabilised by electrostatic forces and an extensive network of hydrogen contacts inv olving anions, cations and water molecules. It is interesting to indic ate that in both cases the polyanions are joined by means of hydrogen contacts O ... O of medium character. Raman and Fourier transform infr ared spectra of both compounds have been recorded. The electron spin r esonance spectra of compound 1 indicate that the chromophore is distor ted with respect to the ideal octahedron, and also demonstrate the exi stence of a certain contribution of spin-orbit coupling that mixes the fundamental state with the first excited states. For compound 2 the e xistence of two different chromophores is seen; one of them correspond s to that observed for compound 1 while the other is due to a more dis torted environment.