Syntheses, Structures and Properties of Two Luminous Mercury(II) Bromides Containing Tridentate N-Donor Schiff Bases: Control of Coordination Number and Nuclearity by Varying Ligand Matrices.

Mononuclear [Hg(L1)Br] ( 1) and 1D polymer [Hg(L2)Br] ( 2) [L1 = ( N, N-diethyl, N′-(pyridin-2-yl)formylidene)ethane-1,2-diamine and L2 = ( N, N-diethyl, N′-(pyridin-2-yl)benzylidene)ethane-1,2-diamine] have been synthesized using appropriate molar ratios of HgBr and L1/L2 in methanol-acetonitrile solution mixtures at room temperature. Crystal structures were investigated with the help of single crystal X-ray diffraction data. In 1, the mercury(II) center adopts a distorted square pyramidal geometry bound by three N atoms of L1 and two terminal bromides. Compound 2 forms a 1D chain through Hg-Br-Hg bridges in an infinite fashion connecting two crystallographically independent mercury(II) centers; Hg1 is in a distorted square pyramidal environment coordinated by three N atoms of L2 and two bridging bromides, whereas Hg2 adopts a tetrahedral geometry bound by two terminal and two bridging bromides. 1 and 2 display intraligand (π−π*) fluorescence in DMF solutions at room temperature. Graphical Abstract: [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]