Penta-coordinated Cr(II) and Cu(II) complexes appended with 4 ' -(4-quinolyl)-2,2 ':6 ',2 '' -terpyridine: Crystal structure, Hirshfeld surface analysis, luminescence and thermal properties

Two new chromium and copper complexes containing 4 ' -(4-quinolyl)-2,2 ' :6 ' ,2 ' '-terpyridine (qtpy) have been synthesized and characterized using elemental analysis, IR and X-ray crystal structure determination. The reaction of CrCl 3 . 6H 2 O with qtpy in presence of granulated zinc as a reducing agent has been resulted in the formation of the new terpyridine chromium(II) complex [Cr(qtpy)Cl 2 ] ( 1 ). Moreover, the reaction of CuBr 2 with qtpy affords the new complex [Cu(qtpy)Br 2 ] ( 2 ). Recrystallization of 1 from DMF and recrystallization of 2 from DMSO yield the respective solvates, [Cr(qtpy)Cl 2 ] . DMF ( 1. DMF) and [Cu(qtpy)Br 2 ] . 2DMSO ( 2. 2DMSO), confirmed by X-ray single crystal analysis. The crystal structures of isostructural complexes [Cr(qtpy)Cl 2 ] . DMF ( 1. DMF) and [Cu(qtpy)Br 2 ] . 2DMSO ( 2. 2DMSO) reveal that chromium(II) and copper(II) adopt the penta-coordinated square pyramidal geometry in which Cr and Cu are coordinated by three nitrogen atoms of qtpy and two Cl - for 1. DMF, and two Br - for 2. 2DMSO. As well, the crystal packings of complex 1. DMF, and 2. 2DMSO clearly show the formation of supramolecular structures through C-H...X (X = N, O, halide) hydrogen bond interactions. The 3D Hirshfeld surface analysis and 2D fingerprint maps were used for quantitative mapping out of the intermolecular interactions for 1. DMF, and 2. 2DMSO. Luminescence properties of 1 and 2 displayed the ligand-based pi-pi* emission bands in solution. Thermal properties of 1 and 2 show that they undergo thermal decomposition and the corresponding metal oxide formed in each case.