Structural conformation and coordination architecture investigation in the solvent induced cis Cu(II) complex containing fluorine-substituted β-diketonate ligand

Abstract

The modification in structural conformation, coordination bonds, and hydrogen bonding has been investigated in the solvent-induced Cu(II) complex with 4,4,4-Trifluoro-1-phenyl-1,3-butanedione. A new β-diketone-based Cu(II) complex [Cu(TFPB)2(DMSO)] has been identified and structurally characterized. Single-crystal X-ray diffraction analysis revealed that the [Cu(TFPB)2(DMSO)] (complex 1) is crystallized in triclinic (P1¯) and complex [Cu(TFPB)2] (complex 2), which was reported earlier, is in the monoclinic (P21/n) system. The Cu(II) complex with coordinated solvent (complex 1) features a five-coordination with doubly chelated -O donors of β-diketone in basal positions and the oxygen atom of DMSO solvent supplementing the fifth coordination site. The coordination geometry around the metal centre is described as a slightly distorted square pyramidal with the trigonality index τ5 of 0.0586. While in solvent-free complex (complex 2), two β-diketone molecules are coordinated to a central Cu(II) ion in a basal position to form a perfect square planar geometry with τ4 of zero. Interestingly, the oxygen donors of β-diketone in complex 1 are inclined in a cis configuration, whereas in complex 2, they are aligned in a trans configuration. The changes in molecular orbital energies and reactive chemical descriptors in the solvent-induced complexes were studied by the electronic structure method. A relatively lower energy gap value is observed for the trans (3.1119 eV) form than cis (3.2186 eV). In addition, molecular docking analysis was performed to investigate the influence of structural variation of complexes on the binding modes and protein-ligand interactions with the penicillin-binding protein 2.