Synthetic methods for [Et(4)N](4)[W4Cu4S12O4] (1), [Et(4)N](4)[Mo4Cu4S12O4] (2), [W4Cu4S12O4(CuTMEN)(4)] (3), and [Mo4Cu4S12O4(CuTMEN)(4)] (4) are described. [Et(4)N](2)[MS(4)], [Et(4)N](2)[MS(2)O(2)], Cu(NO3)(2) . 3H(2)O, and KBH4 (or Et(4)NBH(4)) were used as starting materials for the synthesis of 1 and 2. Compounds 3 and 4 were produced by reaction of [Et(4)N](2)[WOS3], Cu(NO3)(2) . 3H(2)O, and TMEN and by reaction of [Me(4)N](2)[MO(2)O(2)S(8)], Cu(NO3)(2) . 3H(2)O, and TMEN, respectively. Crystal structures of compounds 1-4 were determined. Compounds 1 and 2 crystallized in the monoclinic space group C2/c with a = 14.264(5) Angstrom, b = 32.833(8) Angstrom, c = 14.480(3) Angstrom, beta = 118.66(2)degrees, V = 5950.8(5) Angstrom(3), and Z = 4 for 1 and a = 14.288(5) Angstrom, b = 32.937(10) Angstrom, c 14.490(3) Angstrom, beta = 118.75(2)degrees, V = 5978.4(7) Angstrom(3) and Z = 4 for 2. Compounds 3 and 4 crystallized in the trigonal space group P3(2)21 with a = 13.836(6) Angstrom, c = 29.81(1) Angstrom, V = 4942(4) Angstrom(3), and Z = 3 for 3 and a = 13.756(9) Angstrom, c = 29.80(2) Angstrom, V = 4885(6) Angstrom(3), and Z = 3 for 4. The cluster cores have approximate C-2v, symmetry. The anions of 1 and 2 may be viewed as consisting of two butterfly-type [CuMOS(3)Cu] fragments bridged by two [MOS(3)](2-) groups. Eight metal atoms in the anions are arranged in an approximate square configuration, with a Cu(4)M(4)S(12) ring structure. Compounds 3 and 4 can be considered to consist of one [M(4)Cu(4)S(12)O(4)](4-) (the anions of 1 and 2) unit capped by Cu(TMEN)(+) groups on each M atom; the Cu(TMEN)(+) groups extend alternately up and down around the Cu(4)M(4) square. The electronic spectra of the compounds are dominated by the internal transitions of the [MOS(3)](2-) moiety. Mo-95 NMR spectral data are investigated and compared with those of other compounds.