SYNTHESIS AND CRYSTAL-STRUCTURE OF [NB-2(S1.72SE2.28)(S(2)CNET(2))(4)] - A SOLID-SOLUTION BASED ON [NB-2(MU(2),ETA(2)-X(2))(2)(S(2)CNET(2))(4)], WHERE X(2)=S-2, SSE, AND SE-2 - NEW MODEL OF STRUCTURE REFINEMENT OF [NB-2(S-2)(2)(S(2)CNET(2))(4)]

The crystal structure of [Nb-2(S1.72Se2.28)S(2)CNEt(2))(4)], which is a solid solution based on [Nb-2(mu(2),eta(2)- X(2))(2)(S(2)CNEt(2))(4) ], where X(2) = S-2, SSe, and Se-2, is determined. The compound was ob tained by the reaction of NaS(2)CNEt(2) in CH3CN with the product of t he reaction of the NbSe2Cl2-KNCS fusion cake with an aqueous solution of Bu(4)NBr (yield 30%). The crystals are monoclinic, a = 21.319(11), b = 7.008(1), c = 16.673(8) Angstrom, beta = 133.99(2)degrees, V-cell = 1792(1) Angstrom(3), space group C2/m, Z = 2, d(calc) = 1.879 g/cm(3 ) for C20H40N4Nb2S9.72Se2.28, Syntex P2(1), lambda CuK alpha, N-meas/c orr = 2423/1191, R(F) = 0.0569 and wR(F-2) = 0.1282 for 889 F-hkl > 4 sigma(F). The compound is isostructural to the thio analog Nb2S4(S(2)C NEt(2))(4) studied earlier; in both cases, the molecule is disordered in crystals over two positions. The composition was refined by diffrac tion data. The results are in good agreement with the Raman and FMB (f ast molecule bombardment) mass spectrometry data. The structure of Nb2 S4(S(2)CNEt(2))(4) was refined for the second time using a new model o f disorder; as a result of the refinement, a normal value of S-S bond length in the S-2 ligand [2.027(5) Angstrom] was obtained.