A Series of Pentanary Salt-Inclusion Chalcogenoborates Containing a B12Q12 (Q = S, Se) Cluster Exhibiting a Kleinman-Forbidden Frequency-Doubling Effect

A series of pentanary chalcogenoborates (A 3 X)[InB 12 (InQ 4 ) 3 ] (A = K, Rb, Cs; X = Cl, Br, I; Q = S, Se) were obtained by high-temperature solid-state reactions. These salt-inclusion chalcogenides crystallize in the hexagonal space group P 6 3 22, a type of Kleinman-forbidden noncentrosymmetric structure. Their structures feature a [InB 12 (InQ 4 ) 3 ] open framework built by InQ 6 octahedra and InQ 4 tetrahedra consolidated B 12 cluster, which accomodates octahedral cavities for XA 6 units. They are second-harmonic generation active, and their optical properties were studied experimentally and theoretically. This work can evoke more interest in chalcogenoborate-based second-order nonlinear optical materials.