Density functional theory implemented in ADF 2009.01 was used to calculate the values of two ESR parameters namely effective spin Hamiltonian [H^] and hyperfine coupling energy (?E hf) along with the values of four factors (g, a, Q, and I) which contribute to the total value of the Hamiltonian for 45 complexes of six congeners of 2nd and 3rd transition series metal ions such as Zr (III) , Hf (III) ; Nb (IV), Ta(IV) ; Mo(III), W(III) ; Tc (II), Re(II) ; Ru (III), Os(III) ; Rh (IV), Ir (IV). Four relations which hold good both in regular (Oh) as well as distorted stereochemistries (D6h, D3d, D12, C2v, C1, C2) of these complexes were applied. The basis sets used were DZ or TPZ. The complexes were optimized to obtain ESR (g11, g22, g33, giso ; a11, a22, a33, A ten) and NQR parameters [?; q11, q22, q33 and NQCC] which were then used to calculate [H^] and [?Eh f].