Single crystal EPR of studies Ni(II) in hexaimidazole zinc(II)dichloride tetrahydrate: a case of rhombic distortion

Identification of crystal symmetry in Kramers and non‐Kramers ions by optical absorption: Divalent copper and nickel ions in diamagnetic lattices

“…However, in the present investigation, the 3 A 2g → 1 E g transition remains unsplit. Hence, one can pronounce from the optical studies that the geometry around the Ni(II) ion has undergone trigonal distortion rather tetragonal distortion, as also confirmed by EPR, in which the symmetry is proved to be orthorhombic, as mentioned earlier [5].…”

“…B for a free Ni(II) ion is 1084 cm -1 , which indicates a reduction of about 24% from the free ion value. The EPR analysis of Ni(II)/HZDT has been reported in an earlier communication [5]. The optical data and EPR data can be correlated to obtain the individual spin-orbital coupling parameter (λ) using the formula g = 2.0023 -8λ/∆ Here, ∆ is the energy of the transition in perfect octahedral case.…”

“…The optical data and EPR data can be correlated to obtain the individual spin-orbital coupling parameter (λ) using the formula g = 2.0023 -8λ/∆ Here, ∆ is the energy of the transition in perfect octahedral case. Using the g value obtained from EPR analysis [5] and ∆ from optical data, the value of λ obtained is 225 cm The total spin-orbital coupling parameter (ξ) is also calculated using the formula λ = ± ξ/2S. Here the + sign is required for a shell that is less than half-filled and the -sign for more than half-filled shell.…”

“…Imidazole and histidine ligands are bound to many proteins and metal containing enzymes. The EPR studies of this host lattice (HZDT), when doped with paramagnetic ions such as Cu(II), Cr(III), Fe(III), Mn(II) and Ni(II) [1][2][3][4][5], have given interesting results. Cu(II) has undergone Jahn-Teller distortion, Cr(III) behaves concentration dependent sites with large zero-field splitting (D), Fe(III) under the influence of a strong tetragonal distortion, Mn(II) shows twinning and Ni(II) shows EPR spectrum at room temperature itself with large D. However, the optical studies have not yet reported for these ions.…”

Interstitial substitutions of vanadyl ions doped in single crystals of hexaimidazole cobalt sulphate: An EPR study

“…In addition, transition metals like Cu(II), Cr(III), Fe(III), Mn(II) and Ni(II) are doped in an imidazole complex, such as hexaimidazole zinc(II)chloride tetrahydrate (HZDT) [13 -17], where the host lattice is diamagnetic. For example, single crystals of Ni(II)/HZDT [17] have given EPR spectrum even at room temperature, not so common, and the system exhibits rhombic distortion. However, attempts to dope vanadyl ion, i.e., VO(II), in HZDT are not successful, may be due to the difficulty in replacing one of the imidazole groups in the lattice by vanadyl impurity.…”