Reactivity of the [MoS_4Cu_6Br_8]~(4-) anion toward polyarylphosphorus ligands; synthesis, characterization and nonlinear optical properties of [MoS_4(Cudppf)_2]·2DMF·CH_3CN and [MoS_4Cu_2(Ph_2PPy)_4]

摘要

[NH_4]_2[MoS_4] reacts with CuBr and [Bu_4N]Br in the solid state to afford an intermediate product with proposed constitution [Bu_4N}_4[MoS_4Cu_6Br_8] (1). Treatment of cluster (1) with an equal equivalent of dppf in CH_3CN-DMF solution resulted in the formation of a pentanuclear cluster [MoS_4(Cudppf)_2]·2DMF·CH_3CN (2). Cluster (2) crsytallizes in the monoclinic space group P2_1 with four formula units in a cell of dimensions a = 13.1267(8), b = 38.040(2), c = 15.2661(9)A, and #beta# = 97.6030(10)°. Refinement by full-matrix least-squares techniques gave final residuals R = 0.0567 and wR = 0.1679. The structure of (2) can be described as two (Cudppf)~+ units linked through MoS_2~(2-) to form a pentanuclear folding-ruler array. Reaction of (1) with excess Ph_2PPy in CH_3CN solution resulted in the formation of a trinuclear cluster [MoS_4Cu_2(Ph_2PPy)_4] (3). Cluster (3) crystallizes in the tetragonal space group I4_1/a with cell constants a = 17.427(6), b = 17.427(6), c = 21.344(5)A, and Z = 4. Final residueals R = 0.337 and wR = 0.0616. The structure of (3) is built up from two Cu(Ph_2PPy)_2~+ units bridged by a MoS_4~(2-) ligand to form a trinuclear symmetrical linear molecule. Clusters (20 and (3) exhibit strong optical absorption (effective a_2 = 1.6 X 10~(-9) m W~(-1) (2) and 1.2 X 10~(-9) m W~(-1) (3)) and optical self-defocusing effects (n_2 = 1.35 X 10~(-17) m~2 W~(-1) (2) and - 6.84 X 10~(-17) m~2 W~(-1) (3)), their limiting thresholds were determined to be 0.35 J cm~(-2) (2) and 0.65 J cm~(-2) (3), which are about four and two times, respectively, better than that of C_60.