The Correlation between Calculated Electrostatic Potential and Crystal Structures; Theoretical Study and the Crystal Structure of 3-Bromopyridinium Aquatrichlorocuprate(II)

The supramolecular structure of (3BP)[Cu(H2O)Cl3] (3BP = 3-bromopyridinium cation) is developed based on N-H···Cl, N-H···O , C-Br···Cl, O-H···Cl and Cu···Cl interactions. Cu···Cl semi- coordinate bond and O-H···Cl hydrogen bonding interactions connect [Cu(H2O)Cl3]- anions to form chains. The two legs of the bifurcated hydrogen bonding interactions of the pyridinium cation nitrogen (N-H···Cl and N-H···O) link these chains to form layer structures. The three- dimensional structure is developed by interdigitating these layers based on C-Br···Cl halogen bonding interactions. The energy of the interactions N-H···Cl and C-Br···Cl was calculated, the N- H···Cl hydrogen bonding interactions are found stronger than the analogous C-Br···Cl halogen bonding interactions. The calculated electrostatic potential of 3BP+ cation and [Cu(H2O)Cl3]- anion was used to describe cation-anion, inter-anions and inter-cations interactions and the relative strength of the N-H···Cl and C-Br···Cl interactions. Moreover, the electrostatic potential model was found to be efficient in describing the arrangement of [Cu(H2O)Cl3]- anions inside crystalline lattices in all crystal structures published in Cambridge Structural Data Base (CSD).