Syntheses and Characterizations of a Series of Tetradecanuclear Molybdenum(Tungsten)/Copper/Sulfur Heterobimetallic Cluster Compounds.

Using sulfide ion to substitute the weakly copper(I)-philic ligands of MS(4)(-)(n)()(2)(-)O(n)()/Cu(+) compounds, (M = Mo, W; n = 0, 1), we have prepared and characterized four novel tetradecanuclear clusters having the general formula [(n-Bu)(4)N](4)[M(4)Cu(10)S(16)E(2)E']H(2)O, (M = Mo, E = E' = O for complex 1; M = W, E = (1)/(2)O + (1)/(2)S, E' = O, for complex 2; M = Mo, E = S, E' = (1)/(2)O + (1)/(2)S for complex 3; M = W, E = E' = S, for complex 4). Crystal structures of compounds 1-4 were determined; they are isomorphous and crystallized in the orthorhombic space group Pna2(1), with a = 26.6997(2) Å, b = 19.3133(4) Å, c = 21.4577(4) Å, V = 11064.9(3) Å(3), Z = 4 for [(n-Bu)(4)N](4)[Mo(4)Cu(10)S(18)O].H(2)O (3) and with a = 26.8141(8) Å, b = 19.4412(6) Å, c = 21.4039(5) Å, V = 11157.8(5) Å(3), Z = 4 for [(n-Bu)(4)N](4)[W(4)Cu(10)S(19)].H(2)O (4). The cluster cores have approximate sigma symmetry. The anions 1-4 may be viewed as consisting of one incomplete cubane-like Cu(3)MS(3)E fragment, one trigonal prism-type Cu(3)MS(4), and two butterfly-type Cu(2)MS(3)E' fragments, bridged by two &mgr;(3)-S and one &mgr;(4)-S atoms. There are two (&mgr;(3)-S)Cu(3) configurations in the compounds. Infrared, Raman, and UV/vis spectra of the above compounds are discussed, and the main absorption bands are assigned. (95)Mo NMR spectra and cylic voltammograms are investigated and compared with those of other compounds, (95)Mo NMR spectra show that in the solution there are three kinds of coordination environments of Mo in complexes 1 and 3, and cyclic voltammograms indicate that complexes 1-4 have irreversible electrochemical reductions.