Diaquabis(ethylenediamine)copper(II) vs. monoaquabis (ethylenediamine)copper(II): Synthesis, characterization, single crystal X-ray structure determination, theoretical calculations and antimicrobial activities of [Cu(en)2(H2O)2](2-phenoxybenzoate)2•H2O and [Cu(en)2(H2O)](diphenylacetate)2•3H2O

Two new copper(II) complexes of composition [Cu(en)(2)(H2O)(2)(2-phenoxybenzoate)(2)center dot H2O, 1 and [Cu (en)(2)(H2O)](diphenylacetate)(2)center dot 3H(2)O, 2 (where en = ethylenediamine) have been synthesized, characterized by elemental analyses, spectroscopic techniques (UV-vis and FT-IR), magnetic moment determination and conductance measurements and their structures have been unequivocally confirmed by single crystal X-ray analysis. Both complexes crystallize in the monoclinic crystal system with space groups C2/c, for 1 and P2(1)/n, for 2. Complex 1 exhibits a distorted octahedral geometry with four nitrogen atoms of chelating en ligands and two oxygen atoms of water molecules coordinated to central Cu(II) ion, whereas complex 2 shows a square pyramidal geometry around copper(II) with four nitrogen atoms of chelating en ligands and one oxygen atom of water molecule. Crystal structures of both complexes are stabilized by collective interplay of various non-covalent interactions such as O-H center dot center dot center dot O, N-H center dot center dot center dot O and C-H center dot center dot center dot pi interactions, besides electrostatic attraction. DFT optimization studies clearly showed that complex 2 is quite stable with square pyramidal geometry than expected octahedral geometry. Both complexes show potential antibacterial activities against gram positive and gram negative bacteria. (C) 2016 Elsevier Ltd. All rights reserved.