Syntheses,Crystal Structures and Non‐linear Optical Properties of Cluster Compounds [MoAu2S4(PPh2Py)2] and [WAu2S4(PPh2Py)2]

The cluster compounds, [MoAu₂S₄(PPh₂Py)₂] ( 1 ) and [WAu₂S₄(PPh₂Py)₂] ( 2 ), were synthesized by the reaction of (NH₄)₂MS₄ (M = Mo, W), H[AuCl₄]·4H₂O and diphenyl‐2‐pyridyl‐phosphine (PPh₂Py) in CH₂Cl₂ solution. [MoAu₂S₄(PPh₂Py)₂] crystallizes in the monoclinic space group P2₁/c with a = 18.385(2), b =12.304(1), c = 16.904(2) Å, β =110.722(2)°, and Z = 4. [WAu₂S₄(PPh₂Py)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 n₂ values of compound 2 are 4.35 × 10^—11 m · W^—1 and 3.73 × 10^—17 m² · W^—1.