Chemistry of thiocarboxylates: Synthesis and structures of neutral copper(I) thiocarboxylates with triphenylphosphine

The reactions of Na+ R{O}CS- (R = Me, Ph) with mixtures of CuCl and PPh3 in stoichiometric ratios yielded the compounds [Cu-4(SC{O}Me)(4)(PPh3)(4)] (1), [Cu-4(SC{O}Ph)(4)(PPh3)(3)] (2), [Cu-2(SC{O}Me)(2)(PPh3)(4)] (3), [Cu-(SC{O}Ph)(PPh3)(2)] (4), and [Cu-2(SC{O}Ph)(2)(PPh3)(3)] (5) quantitatively. Compound 2 was also obtained from mixtures of CuCl, PPh3, and NaSC{O}Ph in the ratio 1:1:1. The analogous thioacetate compound similar to 2 and the thiobenzoate analogue of 1 could not be obtained. Attempts to prepare the unsymmetrical dimer of a thioacetate compound similar to 5 gave a mixture of 1 and 3. The structures of 1-4 have been determined by single-crystal X-ray diffraction methods. Crystal data for 1: triclinic space group P (1) over bar, a = 11.5844(3) Angstrom, b = 13.2459(3) Angstrom, c = 14.3433(3) Angstrom, alpha = 64.019(1)degrees, beta = 79.297(1)degrees, gamma = 69.426(1)degrees, V = 1850.48(7) Angstrom(3), Z = 1, D-calcd = 1.439 g.cm(-3). Crystal data for 2.0.5CH(2)Cl(2). H2O: triclinic space group P (1) over bar, a = 12.4413(1) Angstrom, b = 15.5443(1) Angstrom, c = 20.4637(3) Angstrom, alpha = 94.474(1)degrees, beta = 95.976(1)degrees, gamma = 106.450(1)degrees, V= 3848.09(7) Angstrom(3), Z = 2, Dcalcd = 1.416 g.cm(-3). Single-crystal data for 3: monoclinic space group P2(1)/n, a = 15.2746(2) Angstrom, b = 23.2947(2) Angstrom, c = 19.0518(3) Angstrom, beta = 96.713(1)degrees, V = 6732.5(2) Angstrom(3): Z = 4, D-calcd = 1.309 g . cm(-3). Crystal data for 4: triclinic space group P (1) over bar, a = 10.2524(3) Angstrom, b = 12.9826(4) Angstrom, c = 14.5340(4) Angstrom, alpha = 87.723(1)degrees, beta = 75.322(1)degrees, gamma = 75.978(1)degrees, V= 1815.14(9) Angstrom(3), Z = 2, D-calcd = 1.327 g.cm(-3). Compound 1, [(mu(3)-SC{O}Me-S)(2)(mu-SC{O}-Me-S)(2)(CuPPh3)(4)], is a tetramer with a distorted stepladder structure in which two copper atoms are trigonally coordinated and the other two are tetrahedrally coordinated. Two bonding modes, namely, mu(3)-S and mu(2)-S, were observed for the Me{O}CS- anion. The structure of 2 may be described as a highly distorted cubanoid structure and formulated as [(mu(3)-SC{O}Ph-S-3)(mu(3)-SC{O}Ph-S-2,O)(3)(Cu)(CuPPH3)(3)]. In 2, three copper atoms have tetrahedral coordination geometry and one: copper atom is trigonally coordinated. Unprecedented bonding modes, namely, mu(3)-S, have been observed for the R{O}CS- anions, in 1 and 2 and mu(3)-S-2,O in 2. Compound 3, [(mu-SC{O}Me-S)(mu-SC{O}Me-S,O){Cu(PPh3)(2)}(2)] is a dimer with mu(2)-S and mu(2)-S,O bonding modes of Me{O}CS- ligands. Monomeric structure was found in 4 in which the copper atom has trigonal planar geometry with a very weak intramolecular interaction with O. Variable temperature P-31 NMR studies in solution show the presence of various species in equilibria.