Inorganic Chemistry, Vol.46, No.26, 11381-11389, 2007
Reactions of a tungsten trisulfido complex of hydridotris(3,5-dimethylpyrazol-1-yl)borate (Tp*) [Et4N][Tp*WS3] with CuX (X = Cl, NCS, or CN): Isolation, structures, and third-order NLO properties
Reactions of a tungsten trisulfido complex of hydridotris(3,5-dimethylpyrazol-1-yl)borate (Tp*) [Et4N][Tp*WS3] (1) with 3 equiv of CuCl in CHCl3 afforded a tetranuclear anionic cluster [Et4N][Tp*W(mu(3)-S)(3)(CUCl)(3)] (2), while that of 1 with 3 equiv of CuNCS in MeCN produced a decanuclear neutral cluster (major product) [Tp*W(mu(3)-S)(3)CU3(mu-NCS)(3)(CUMeCN)](2) (3) along with a binuclear anionic cluster (minor product) [Et4N][Tp*WO(mu-S)(2)(CuNCS)] (4). Solvothermal reactions of 1 with 3 equiv of CuCN in MeCN at 80 degrees C for 48 h followed by slowly cooling it to ambient temperature gave rise to a polymeric cluster [TP*W(mu(3)-S)(mu-S)(2)Cu-2(MeCN)(mu-CN)](n) (5). Compounds 2-5 were characterized by elemental analysis, IR, UV-vis, H-1 NMR, and single-crystal X-ray crystallography. The cluster anion of 2 has a [Tp*WS3Cu3] incomplete cube with one Cl atom coordinated at each Cu center. 3 is composed of an unprecedented centrosymmetric W2Cu8 Cluster core in which each void of the two single incomplete cubane-like [Tp*W(mu(3)-S)(3)CU3(mu-NCS)](+) cations is partially filled with an extra [Cu(MeCN)(mu-NCS)(2)](-) anion via a pair of Cu-mu-NCS-Cu bridges. The cluster anion of 4 contains one WS2Cu core that is formed by an oxidized [Tp*WO(mu-S)(2)] species and one CuNCS fragment. 5 consists of butterfly shaped [Tp*W(mu(3)-S)(mu-S)(2)Cu-2(MeCN)] fragments that are interconnected via cyanide bridges to form a 1D spiral chain extending along the c axis. The successful synthesis of 2-5 from 1 suggests that 1 may be an excellent synthon to the W/Cu/S clusters. In addition, the third-order nonlinear optical (NLO) properties of 1-3 in solution were also investigated by femtosecond degenerate four-wave mixing (DFWM) technique with a 80 fs pulse width at 800 nm. Although 2 was not detected to have NLO effects, 1 and 3 exhibited relatively good optical nonlinearities with the nonlinear refractive index n(2) and the third-order nonlinear optical susceptibility X-(3) values being 0.79 x 10(-13) and 0.38 x 10(-14) esu (1) and 2.08 x 10(-13) and 1.00 x 10(-14) esu (3), respectively. The second-order hyperpolarizability gamma value for 3 (5.46 x 10(-32) esu) is ca. 5 times larger than that of its precursor 1.