Influence of intramolecular ring-ring π,π-interaction on crystal building in ternary compound of nickel(II) chelates of 2,2’-{[2-(4-methylphenyl)ethyl]azanediyl} diacetic acid and 1,10-phenanthroline – Synthesis, spectral, optical and quantum chemical study

Abstract

The stoichiometric reaction between Ni(II) hydroxy-carbonate and N-(p-methyl-phenethyl)-Iminodiacetic acid ligand (HMEpheida) in aqueous media leads to binary complex of the type [Ni(MEpheida)(HO)]·xHO which gives ternary complex of the formula [Ni(MEpheida)(phen)(HO)]·3HO on the addition of 1,10-phenanthroline (1,10-phen) in equimolar ratio. The compound has been characterized by means of elemental analysis, FTIR, UV-Vis, TGA and X-ray crystallography. The weak ring-ring intramolecular π,π-interaction between phen and benzene ring of MEpheida affects the crystal pattern of the complex (triclinic, space group P-1) reported herein. Crystallographic information reveals the distorted octahedral geometry of the type 1+2+2+1 (lesser Jahn-Teller distortion) around the Ni(II) ion with full and half occupancy of t and 3dx-y, 3dz orbitals respectively. The iminodiacetate moiety of metal-chelate adopts fac-NO conformation. Moreover, the quantum chemical calculations and HOMO-LUMO energy gap along with the other global descriptors have been performed for the HMEpheida and [Ni(MEpheida)(phen)(HO)] complex using DFT/B3LYP methodology. The optical bandgap energy (E) for ligand and Ni(II) complex have been estimated through Tauc’s equation, αhν = A(hν-E), where r = ¿ for indirect and 2 for direct electronic transitions using electronic absorption data. The direct and indirect electronic transition bandgap calculated for Ni(II) complex 3.97 and 3.76 eV respectively, reflecting their semi-conducting nature.