PHENYLIMIDO DERIVATIVES OF [MO6O19]2- - SYNTHESES, X-RAY STRUCTURES, VIBRATIONAL, ELECTROCHEMICAL, MO-95 AND N-14 NMR-STUDIES

Both [Mo6O18(NPh)]2- and [Mo6O17(NPh)2]2- species are formed by reaction of (n-Bu4N)2[Mo6O19] with either 1 or 2 equiv. of Ph3P = NPh in pyridine or acetonitrile and have been isolated as mixtures. Single-crystal X-ray diffraction analyses have shown that [Mo6O18(NPh)]2-, [Mo6O17(NPh)2]2- and [Mo6O19]2- can be found together in the same crystal of average composition (n-Bu4N)2[Mo6O19-x(NPh)x]. The structural parameters of the averaged anions have been determined for x = 1.16 (sample 1) and x = 0.92 (sample 2). Crystal data for 1: a = 12.684(4), b = 22.750(4), c = 19.483(3) angstrom, beta = 103.04(2)-degrees, space group P2(1)/c, Z = 4, R = 0.048 and R(w) = 0.051 for 3846 reflections with I greater-than-or-equal-to 3sigma(I). Crystal data for 2: a = 12.678(2), b = 22.645(3), c = 19.462(4) angstrom, beta = 104.16(2)-degrees, space group P2(1)/c, Z = 4, R = 0.058 and R(w) = 0.061 for 5243 reflections with I greater-than-or-equal-to 3sigma(I). The products have been studied in acetonitrile solution by Mo-95 and N-14 NMR spectroscopy, Raman spectrophotometry and electrochemistry. Each of these techniques has confirmed the presence of the mono- and bis-imido derivatives together with the parent species, and has allowed both the characteristics of the individual components and the composition of the solution to be determined; the results obtained by the different methods are in resonable agreement.