“…In recent years, researchers have successfully synthesized compounds with excellent NLO properties by combining d 10 metals with π-conjugated anions of triangular planar geometry, especially in borate and carbonate systems, such as AZn 2 (BO 3 )Si 2 O 5 (A = Rb, Cs), Cd 4 BiO(BO 3 ) 3 , CsZn 2 BO 3 X 2 (X 2 = F 2 , Cl 2 , and FCl), LiZn(OH)CO 3 , Ba 5 Zn 4 (BO 3 ) 6 , and KCdCO 3 F. ,− However, the d 10 metal nitrate NLO crystals have shown very limited reports. Only A 2 Hg(NO 3 ) 4 (A = K, Rb), Na 10 Zn(NO 3 ) 4 (SO 3 S) 4 , Na 10 Cd(NO 3 ) 4 (SO 3 S) 4 and PbCdF(SeO 3 )(NO 3 ) exhibit SHG effects. ,,, Prominently, A 2 Hg(NO 3 ) 4 (A = K, Rb) demonstrate strong SHG effects of 8.8–9.2 times than that of KDP . Note that Hg 2+ ions can adopt multiple coordination configurations, including linear, trigonal planar, and tetrahedral units, which contribute to the diversity of structural variations.…”