Noncentrosymmetric Cubic Cyanurate K6Cd3(C3N3O3)4 Containing Isolated Planar π-Conjugated (C3N3O3)3– Groups

Single crystals of K 6 Cd 3 (C 3 N 3 O 3 ) 4 ( 1 ) were successfully grown via a solid-state cyclotrimerization reaction method from CdCl 2 and KOCN. To our best knowledge, it is the first inorganic compound containing isolated six-membered-ring (6-MR) anionic groups that crystallizes in the cubic system. In the structure, the basic 6-MR anionic unit is a planar π-conjugated (C 3 N 3 O 3 ) 3– group that is isoelectronic with the (B 3 O 6 ) 3– group, as observed in the benchmark nonlinear-optical (NLO) crystal β-BaB 2 O 4 with strong second-harmonic-generation response. In addition, the electronic structure and linear-optical and NLO properties for 1 were also investigated by the first-principles calculation. The NLO coefficient ( d 14 = 1.17 pm/V) of 1 is about 3 times that of KH 2 PO 4 .