Comparative study of EPR spectra and crystal field effect on local structure for (NiF₆)⁴⁻coordination complex in Ni²⁺:ZnF₂, NiF₂, and Ni²⁺:MgF₂systems

Abstract

The present work employs the complete energy matrices for a d 8 configuration ion in a D 2h symmetry ligand field at first time to study the relationship between electron paramagnetic resonance (EPR) spectra and local structure of (NiF 6 ) 4À :MgF 2 systems are reported. Simultaneously, the calculated energy levels are in good agreement with the experimental absorption spectra.

l-Tyrosinatonickel(II) Complex: Synthesis and Structural, Spectroscopic, Magnetic, and Biological Properties of 2{[Ni(l-Tyr)2(bpy)]}·3H2O·CH3OH

“…The replacement of the two imidazole molecules by the chelating 2,2′-bpy molecule brings about slight changes in the d–d band positions. The most important is that it creates a stronger crystal field, which causes splitting of the first and second d–d bands into three components expected for D 2 h symmetry. − …”

“…In D 2 h ( C 2 ″) symmetry, the 3 B 1g term is the ground state and nine spin-allowed transitions, 3 B 1g → 3 A g , 3 B 1g → 3 B 2g , and 3 B 1g → 3 B 3g (I st d–d), 3 B 1g → 3 B 1g , 3 B 1g → 3 B 2g , and 3 B 1g → 3 B 3g (II d–d), 3 B 1g → 3 B 1g , 3 B 1g → 3 B 2g , and 3 B 1g → 3 B 3g (III d–d), are possible as a result of splitting of 3 T 2g ( 3 F, O h ), 3 T 1g ( 3 F, O h ), and 3 T 1g ( 3 P, O h ) states in a rhombic crystal field (Table ). − The three components of the I d–d band are centered at 9460, 10650, and 11210 cm –1 , respectively. The II d–d band includes three separate components obtained at 16060, 17100, and 18600 cm –1 .…”

Tools for magnetostructural correlations for the 3d8(3A2 state) ions at orthorhombic sites: Comparative study with applications to Ni2+ ions in Y2BaNiO5 and Nd2BaNiO5

“…For Ni 2 þ ions in a distorted octahedron in (NH 4 ) 2 Ni(SO 4 ).6H 2 O with the orthorhombic kind II symmetry Feng et al [47] used the expressions [23] to calculate the g-factors, whereas the ZFSPs were calculated using the 'complete diagonalizing' method with the free ion value ζ d ¼ 636 cm À 1 . In view of the inconsistencies in [23] discussed above, the respective results for the g-factors [45][46][47] may need additional verification, since the authors have not pointed out any problems in [23].…”

“…The expressions [23] were applied to calculate the ZFSPs and the g-factors for ZnF 2 :Ni 2 þ and NiF 2 . The two crystals and MgF 2 :Ni 2 þ were also investigated [45] using the same axis system and transformations. However, the complete energy matrices method was utilized in [45] to calculate ZFSPs.…”

“…The two crystals and MgF 2 :Ni 2 þ were also investigated [45] using the same axis system and transformations. However, the complete energy matrices method was utilized in [45] to calculate ZFSPs. Note that ZnF 2 :Ni 2 þ and MgF 2 :Ni 2 þ were also studied using the 'complete energy matrices' method and the semi-self-consistent field d-orbital theory to calculate the optical spectral bands and local structure distortions around Ni 2 þ [46], so no discussion of the axis system was provided therein.…”