Structural, spectroscopic, magnetic behavior and DFT investigations ofl-tyrosinato nickel(ii) coordination polymer

Abstract

New 1D-coordination polymer {[Ni(L-Tyr) 2 (m-4,4 0 -bpy)]Á4H 2 O} n (1) (L-Tyr = L-tyrosine, 4,4 0 -bpy = 4,4 0 -bipyridine) is composed of L-tyrosinate anions chelated nickel(II) centres via N amino and O carboxylate atoms, whereas the apices of the elongated octahedral coordination sphere are occupied by the N atoms of 4,4 0 -bipyridine. Its molecular structure was determined by single-crystal X-ray diffraction and characterized using vibrational (FT-IR), Raman spectroscopy (FT-Raman), electronic (NIR-Vis-UV) and high field electron paramagnetic resonance (HF-EPR) spectroscopy and thermal (TG-DTA, DSC) and magnetic methods. The tetragonality distortion parameter (T) equals 0.945. The g x , g y and g z parameters (HF-EPR spectra) are slightly temperature dependent and the set g x = 2.178(5), g y = 2.156(4), g z = 2.19(1), D = À5.76(2) cm À1 , E = À0.41(1) cm À1 was found at 5 K. The analysis of the temperature and field dependent magnetization shows the weakness of magnetic interactions in 1.

Crystal and electronic structures of Ni(II) silanethiolates containing flexible diamine ligands

“…Positive D and g x , g y > g z are characteristic for Ni 2+ in elongated octahedral coordination[52,53]. Both negative[18,20,54] and positive D[16] were found previously from HF EPR of pseudooctahedral Ni(II) complexes. The EPR g values in hexacoordinated Ni 2+ complexes with distorted octahedral environment are related to the 3 A g → 3 B 1g ,3 A g → 3 B 2g and 3 A g → 3 B 3g transition energies (using D 2h labeling, seeFig…”

Direct Observation of Very Large Zero-Field Splitting in a Tetrahedral NiIISe4 Coordination Complex

“…In each case, at zero field, the sub-THz or THz wave radiation-induced transitions between all three levels are allowed . Magnetometry and HFEPR have been intensively employed in studying high-spin, S = 1, Ni II complexes of various geometries and coordination spheres. − Of particular importance are two recently reported Ni II complexes of different geometry displaying extremely large zfs values, as indirectly estimated by HFEPR (trigonal bipyramidal, D = −120 to −180 cm −1 , E = 1.6 cm −1 ) and by magnetometry alone (trigonal pyramidal, D = −200 cm −1 ) . Only a range of D values has been estimated for the former by observing the |+⟩ → |−⟩ transition (red arrow, Scheme S1) amounting to 2| E | .…”