Syntheses and characterizations of a series of tetradecanuclear molybdenum(tungsten)/cooper/sulfur heterobimetallic cluster compounds

Using sulfide ion to substitute the weakly copper(I)-philic ligands of MS4-n2-On/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)[M4Cu10S16E2E']H2O, (M = Mo, E = E' = O for complex 1; M = W, E = 1/2O + 1/2S, E' = O, for complex 2; M = Mo, E = S, E' = 1/2O + 1/2S 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) Angstrom, b = 19.3133(4) Angstrom; c = 21.4577(4) Angstrom, V = 11064.9(3) Angstrom(3) Z = 4 for [(n-Bu)(4)N](4)[Mo4Cu10S18O]. H2O (3) and with a = 23.8141(8) Angstrom, b = 19.4412(6) Angstrom, c = 21.4039(5) Angstrom, V = 11157.8(5) Angstrom(3), Z = 4 for [(n-Bu)(4)N](4)[W4Cu10S19]. H2O (4) The cluster cores have approximate sigma symmetry. The anions 1-4 may be viewed as, consisting of one incomplete cubane-like Cu3MS3E fragment, one trigonal prism-type Cu3MS4, and two butterfly-type Cu2MS3E' fragments, bridged by two mu(3)-S and one mu(4)-S atoms. There are two (mu(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. Mo-95 NMR spectra and cylic voltammograms are investigated and compared with those bf other compounds, Mo-95 NMR spectra show that in the solution there are three kinds of coordination environments of Mo in complexes 1 and 3, and cyclic voltammogams: indicate that complexes 1-4 have irreversible electrochemical reductions.