EPR and optical studies of Ni(II) ions in Zn(4-chloropyrazole)6(ClO4)2 at 300 K: Probing the structure, bonding, and electron spin relaxation

Abstract

CW EPR and optical absorption studies of Ni(II) ions doped in Zn(C3H3ClN2)6(ClO4)2 (Ni/ZCPC) were carried out at 300 K. The single crystal rotation along three orthogonal axes gave spin Hamiltonian parameters of gx = 2.1961, gy = 2.1679, and gz = 2.1234; Dx = 1014.3, Dy = 913.7, and Dz = −1928.0 G. A progressive CW power saturation study performed at 300 K was used to determine the product of the electron spin–lattice relaxation time and spin–spin relaxation time (T1 × T2) (3.51 × 10−14 s2) for transitions at 4085 and 5740 G. Interestingly, the result demonstrates that Ni/ZCPC is a rare system having the largest T1 × T2 value observed at 300 K compared to other Ni(II) systems reported to date. The optical and EPR data were used to obtain the bonding parameters. The EPR spin Hamiltonian parameters and deconvolution of the optical absorption spectrum reveal that the Ni(II) center has trigonal symmetry.