Abstract
Sulfur-bridged cubane-type molybdenum clusters, [Mo 4S 4(edta) 2] 3− ( 1B), [Mo 4S 4(H 2O) 12] 5+ ( 2B) and [Mo 4S 4(NH 3) 12] 4+ ( 4C), are obtained from [Mo 2O 2S 2(edta)] 2− and NaBH 4, from Mo 2O 2S 2 2+(aq) and NaBH 4, and from 2B and ammonia-water, respectively. The reduced and oxidized forms of 1B, [Mo 4S 4(edta) 2] n− ( n=4 ( 1C) and 2 ( 1A)), and those of 2B, [Mo 4S 4(H 2O) 12] n+ ( n=4 ( 2C) and 6 ( 2A)), are isolated and characterized. The clusters 1B and 2B show two quasi-reversible, one-electron waves. The crystallographic results obtained are as follows: Na 2[Mo 4S 4(edta) 2]·6H 2O ( Na1A), monoclinic, P2 1/ n, a=25.171(4), b=11.231(3), c=13.417(3) Å, β=98.28(1)°, V=3753.4(15) Å 3, Z=4, R=4.41%; Ca 1.5[Mo 4S 4(edta) 2]·13H 2O ( Ca1B), monoclinic, P2 1/ c, a=15.726(8), b=12.447(4), c=28.10(2) Å, β=123.16(3)°, V=4604.6(43) Å 3, Z=4, R=5.53%; Mg 2[Mo 4S 4(edta) 2]·2OH 2O ( Mg1C), monoclinic, P2 1/ m, a=14.358(6), b=13.680(6), c=12.990(5) Å, β=96.56(2)·, V= 2534.8(19) Å 3, Z=2, R=4.79%; [Mo 4S 4(H 2O) 12](CH 3C 6H 4SO 3) 5· 14H 2O ( 2Bpts) (Hpts=paratoluenesulfonic acid), triclinic, P 1 , a=16.352(4), b=16.715(3), c=13.109(4) Å, α=91.05(2), β=98.73(2), γ=89.37(2)°, V=3540.8(16) Å 3, Z=2, R=4.06%; [Mo 4S 4(NH 3), 12]Cl 4·7H 2O ( 4C′), triclinic P 1 , a=10.529(3), b=17.470(4), c=9.967(3) Å, α=96.74(2), β=116.26(2), γ=82.91(2)° , V=1627.4(8) Å 3, Z=2, R=4.50%. The electronic structures of 2A, 2B and 2C were investigated using the spin-polarized discrete variational (DV)-Xα method. The binding energies (eV) of Mo3d 3/2 and Mo3d 5/2 obtained by XPS measurements are: Na1A, 232.7, 229.7; Na 3[Mo 4S 4(edta) 2]· 1OH 2O ( Na1B), 232.1, 229.0; Mg1C, 232.1, 229.0; 2Bpts, 233.0, 230.0; 4C′, 232.1, 228.9.
Published Version
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