Monomeric and dimeric cadmium(II) complexes of N4-phenyl semicarbazones: Spectral features, thermogravimetric analysis, DFT study and crystal structure of a bromido bridged complex

Abstract

Seven cadmium(II) complexes ([Cd(HPySc)Br2] (1), [Cd(HPySc)(OAc)2]·3H2O (2), [Cd(HPySc)Cl2] (3), [Cd(PySc)N3] (4), [Cd(BpSc)(OAc)] (5), [Cd(HBpSc)Cl2] (6), and [Cd2(BpSc)2Br4]) (7) were synthesized using two semicarbazone ligands (HPySc and HBpSc) and characterized by elemental analyses, IR, UV–Vis, thermogravimetric analyses, conductance and single crystal XRD studies. It is found that all the complexes are non-electrolytes in nature and one of the compounds has three molecules of lattice water in the complex. Single crystal study of the complex 7 exhibits a binuclear centrosymmetric structure with a distorted octahedron arrangement around the cadmium(II) centre with Cd⋯Cd non-bonding distance of 4.0809(14) Å. A two-dimensional supramolecular hydrogen bonding network with a zig-zag arrangement is found in the crystal system supported by means of a non-classical hydrogen bonding. DFT calculations reveal that the dimeric complex is the softest and having high chemical reactivity, low stability and high polarizability compared to the other complexes. The NPA and charge distribution analysis indicate that the complexes have significant coordinating sites and potential preferred electron donor sites to metal centers.