{[In 2 S 7 ] 8- } ∞ Chain and Isolated HgS 4 Planar Unit Constructed One-Dimensional Pentanary Sulfide K 2 Ba 7 HgIn 4 S 16 Exhibiting Nonlinear-Optical Activity.

Hg-based chalcogenides possess diverse structures, large nonlinear-optical (NLO) responses, and suitable birefringences, making them potentially suitable for numerous crucial criteria of practical application as infrared (IR) NLO crystals. Here, a new pentanary Hg-based sulfide K 2 Ba 7 HgIn 4 S 16 has been discovered by a high-temperature solid-state method. It crystallizes in the orthorhombic P 2 1 2 1 2 space group, and its one-dimensional structure is constructed by {[In 2 S 7 ] 8- } ∞ chains and isolated [HgS 4 ] 6- planar quadrilateral units located bewteeen the chains, representing a novel type of chalcogenide. K 2 Ba 7 HgIn 4 S 16 exhibits a moderate NLO effect of 0.5 × AGS at 2.1 μm and a high laser-induced damage threshold of ∼5.8 × AGS, as well as a band gap of 2.98 eV, demonstrating that K 2 Ba 7 HgIn 4 S 16 is a potential IR NLO material. This work enriches the structural chemistry of chalcogenides and the family of Hg-based IR NLO chalcogenides.