Syntheses, crystal structures and non-linear optical properties of cluster compounds [MoAu2S4(PPh2Py)2] and [WAu2S4(PPh2Py)2]

Abstract

The cluster compounds, [MoAu2S4(PPh 2Py)2] (1) and [WAu2S4(PPh 2Py)2] (2), were synthesized by the reaction of (NH 4)2MS4 (M = Mo, W), H[AuCl4] ·4H2O and diphenyl-2-pyridyl-phosphine (PPh2Py) in CH2Cl2 solution. [MoAu2S4(PPh 2Py)2] crystallizes in the monoclinic space group P2 1/c with a = 18.385(2), b = 12.304(1), c = 16.904(2) Å, β = 110.722(2)°, and Z = 4. [WAu2S4(PPh 2Py)2] crystallizes in the triclinic space group P-1 with a = 9.333 (3), b = 10.628(3), c = 19.566(6) Å, α = 89.26(1), β = 80.87(1), γ = 68.85(1)°, and Z = 2. Single crystal X-ray analysis showed that these two compounds are isostructural, but belong to different space groups. The Mo (W) atom has a slightly distorted tetrahedral coordination, and the two Au atoms are distorted from trigonal planar, the P-Au-M-Au-P chain is nearly linear. Measurement of the nonlinear optical (NLO) properties using the Z-scan technique with an 8-ns pulsed laser at 532 nm showed that 1 and 2 possess NLO absorption and effective self-focusing effect. The effective α2 and n2 values of cluster 1 are 5.89 × 10-12 m· W-1 and 6.45 × 10-18 m2·W-1; the effective α2 and α2 values of compound 2 are 4.35 × 10-11 m·W-1 and 3.73 × 10-17 m2· W-1.