Structure and Nonlinear Optical Properties of the Cubic Cage Complex (n-Bu4N)3[Cu3MoOS3BrI3]

Unlike the analogous ( n -Bu 4 N) 3 [Cu 3 MoOS 3 Br 4 ], in which the cluster has a partially open cage structure, in the salt ( n -Bu 4 N) 3 [Cu 3 MoOS 3 BrI 3 ] the anion forms a cubane-like cluster, consisting of a (Cu 3 Mo) tetrahedron interlocked with an (S 3 I) tetrahedron. The solid crystallizes in the cubic space group F 4̄3 c ( a = 24.422(3) Å; Z = 8), the cluster adopting 12 allowed orientations randomly. This material exhibits a strong nonlinear optical absorption and a large, self-defocusing refractive index change. This behavior is intermediate between that of analogous nest-shaped clusters with an Mo O group and cubic cage clusters with an Mo S group, indicating that both the nature of the metal−chalcogenide and the overall skeletal structure of the cluster influence the nonlinear optical properties of the material.