New insight into two penta-coordinated multinuclear copper(II) single-armed salamo-based complexes.

Two penta-coordinated multinuclear copper(II) complexes, [Cu 2 (L)(µ -OAc)]·MeOH (1) and [Cu 4 (L) 2 Cl 2 ]·EtOH·CH 2 Cl 2 (2) have been synthesized and characterized structurally. IR spectra, UV–vis spectra and fluorescence properties of complexes 1 and 2 have been investigated. [Display omitted] • Two copper(II) complexes were synthesized and characterized structurally. • All of Cu(II) atoms have the geometries of almost perfect tetragonal pyramid. • Fluorescence properties of complexes 1 and 2 have been investigated. With the reactions of a single-armed salamo-based ligand H 3 L and two kinds of copper(II) salts (Cu(OAc) 2 ·H 2 O or CuCl 2 ·2H 2 O) in mixed organic solvents, respectively, two penta-coordinated Cu(II) complexes [Cu 2 (L)(µ -OAc)]·MeOH (1) and [Cu 4 (L) 2 Cl 2 ]·EtOH·CH 2 Cl 2 (2) have been successfully constructed. The precise structures of the two Cu(II) complexes obtained by solvent evaporation method are measured by single crystal X-ray diffraction analyses. The di-nuclear complex 1 crystallizes in triclinic space group P -1, where the main structure is compose of two Cu(II) atoms, one completely deprotonated ligand (L)3− unit, one bridged μ -OAc− counter-anion and one crystallized methanol molecule. The tetra-nuclear complex 2 with an inversion center crystallizes in the same space group as 1 and contains four Cu(II) atoms, two fully deprotonated salamo-based ligand (L)3− units, two bridged Cl− counter-anions, one crystallized dichloromethane and one ethanol molecules. Compared to preceding complexes based on other single-armed salamo-based ligands, the structure of complex 2 reported in this work is unique and has never been found in previous literatures. All of Cu(II) atoms in complexes 1 and 2 are penta-coordinated with the geometries of distorted tetragonal pyramid, and the τ 5 value of all Cu(II) atoms have been calculated and all results are less than 0.5. Hirshfeld surfaces analyses of complexes 1 and 2 have been established to explain the interactions of crystal structures, and the corresponding two-dimensional (2D) fingerprint plots have been carried out to quantify the intermolecular interactions. In addition, fluorescence properties of complexes 1 and 2 have been investigated. [ABSTRACT FROM AUTHOR]