Predicting ESR Peaks in Titanium (III), Vanadium (IV) and Copper (II) Complexes of Halo Ligands by NMR, ESR and NQR Techniques: A DFT Study

15 halo (I≥1/2) complexes of Ti (III), V (IV) and Cu (II) each possessing one unpaired electron were studied using DFT implemented in ADF.2010.02. A ten , NQCC and η parameters of metal ions and ligands were obtained from ESR/EPR program while their s and δ parameters were given by NMR/EPR program after optimization of complexes. Ligands having same values of these 5 parameters were spatially equivalent and, thus, would undergo same hyperfine interaction. Experimental determination of ESR lines in Cu (II) complexes became erroneous because the presence of both the large Jahn-Teller effect and the high value of its spin-orbit coupling constant (λ Cu (II) = -830 cm-1) affect the A ten parameter adversely. Cryoscopic conditions, generally required, in ESR experiments of Ti (III) and V (IV) complexes were difficult to obtain and cumbersome to maintain.