Sulfur-Bridged Cubane-Type Molybdenum-Gallium Clusters with Mo3GaS4n+ (n = 5, 6) Cores. X-ray Structures of [Mo3GaS4(H2O)12](CH3C6H4SO3)5.14H2O and [Mo3GaS4(H2O)12](CH3C6H4SO3)6.17H2O

Shibahara, Takashi; Kobayashi, Syoji; Tsuji, Naoki; Sakane, Genta; Fukuhara, Minoru

crystal structure molybdenum gallium sulfur cluster; molybdenum gallium sulfur aqua cluster prepn; electrochem redn molybdenum gallium sulfur cluster; cluster cubane molybdenum gallium sulfur prepn
S-bridged cubane-type Mo-Ga clusters [Mo3GaS4(H2O)12]5+ (2) and [Mo3GaS4(H2O)12]6+ (3) were synthesized from [Mo3S4(H2O)9]4+ (1) and Ga metal and were isolated as 2(pts)5.14H2O (2.pts) and 3(pts)6.17H2O (3.pts) (Hpts = p-toluenesulfonic acid), whose structures were characterized by x-ray crystallog.  Crystal data for 3.pts: orthorhombic, space group Pca21, a 11.188(1), b 30.936(4), c 23.987(2) angstrom, Z = 4, R (Rw) = 5.8% (6.3%) for 6102 reflections.  Crystal data for 2.pts: triclinic, space group P-1, a 16.406(4), b 16.743(3), c 13.173(4) angstrom, a 90.64, b 98.40(2), g 89.32(2)degree, Z = 2, R (Rw) = 6.7% (10.1%) for 7612 reflections.  The Mo-Ga distances (3.pts, 3.60[2] angstrom; 2.pts, 3.52[2] angstrom) are much longer than the corresponding Mo-Mo (3.pts, 2.679[7] angstrom; 2.pts, 2.713[3] angstrom) distances.  At low H+ concns., e.g. 0.5M HCl, 2 is stable, and at H+ concn. >2 M HCl, 2 is oxidized by H+ to give 3 with evolution of H2 gas.  Chloride ion plays an important role in the oxidn. of 2.  Electronic spectra of 3.pts and 2.pts are very similar with peak positions and e values (λmax, nm (ε, M-1 cm-1)): 3.pts, 762(447), 550(204); 2.pts, 760(404), 548(205).  The cyclic voltammogram of 3 shows three redn. processes (the cathodic peak potentials, Epc, are -0.83, -1.20, and -1.74 V, resp.), where the 1st and 2nd processes are quasi-reversible (the anodic peak potentials, Epa, are -0.55 and -1.00 V, resp.).  The redn. current of each process is .apprx. 1:1:3.

Inorganic Chemistry

American Chemical Society

36

8

1702

1706