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      https://www.ias.ac.in/article/fulltext/jcsc/133/0099

    • Keywords

       

      Cu(II) malonates; Distorted square pyramid; Hydrogen bonding; π···π stacking; DFT.

    • Abstract

       

      The synthesis, spectra, electrochemical studies, single crystal structures and DFT studies of twonew mixed ligand copper(II) malonates viz. [Cu(H2O)(bpy(OH)2)(mal)].H2O 1 and [Cu(H2O)(dmp)(mal)].2H2O 2 (bpy(OH)2) = 2,2Ꞌ-bipyridine-6,6Ꞌ-diol; dmp = 6,6Ꞌ-dimethyl-1,10-phenanthroline; H2mal =malonic acid) are reported. The malonate, bpy(OH)2 (in 1), dmp (in 2) function as bidentate ligands in thedistorted square pyramidal Cu(II) compounds while the aqua ligand occupies the axial site in 1. In contrast, oneNof dmp occupies the axial site in 2. ESR studies reveal the distorted coordination geometry of Cu(II) in 1 and 2.Extensive hydrogen bonding (O-H···O and C-H···O) is observed between the malonate oxygens, oxygens ofwater and the monomeric Cu(II) species resulting in the formation of hydrogen bonded network structure in 1 and2. The neutral monomeric Cu(II) species and lattice water molecules in 2 are linked viaO-H···Ohydrogen bondforming a water dimer. Both compounds exhibit π···π stacking and carbonyl(lp)···π interactions (in 2) stabilizethe structure. DFT studies reveal stronger hydrogen bond energy for 2 compared to 1, while π···π stacking energyis larger in 1 than in 2 and carbonyl(lp)···π interactions in 2 are found to be moderate. In a series of fivecoordinated mixed ligand Cu(II) malonates, compound 2 exhibits maximum deviation of the {CuN2O3}polyhedron from square pyramidal towards trigonal bipyramidal geometry.

    • Graphical Abstract

       

      The supramolecular network structures of [Cu(H2O)(bpy(OH)2)(mal)]·H2O 1 and [Cu(H2O)(dmp)(mal)]·2H2O 2 are directed by O–H⋅⋅⋅O and C–H⋅⋅⋅O interactions. Additionally π⋅⋅⋅π stacking in 1 and π⋅⋅⋅π /carbonyl(lp)⋅⋅⋅π interactions in 2 contribute to the structure stabilization. 2 is an unique example showing severe distortion of the {CuN2O3} polyhedron.

    • Author Affiliations

       

      MEGHA S DESHPANDE1 SUDESH M MORAJKAR1 MINI BHARATI AHIRWAR2 MILIND M DESHMUKH2 BIKSHANDARKOIL R SRINIVASAN1

      1. School of Chemical Sciences, Goa University, Goa 403206, India
      2. Department of Chemistry, Dr. Harisingh Gour Vishwavidyalaya (A Central University), Sagar 470003, India
    • Dates

       
  • Journal of Chemical Sciences | News

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