Single crystal electronic spectra of a series of trans nickel(II) complexes with N,N′-diethyl- and N,N′-dimethylethylenediamine

Abstract

. Can. J. Chem. 55,3172 (1977). We have measured the polarized crystal spectra at 10 K of Ni(s-Et,en),X,, where X = C1, Br, NCS, and H 2 0 (with C1, Br, and I counterions) and s-Et,en is N,N1-diethylethylenediamine, and of Ni(s-Me,en),X,, where X = NCS and NO3, and s-MeZen is N,N'-dimethylethylenediamine. Transition energies were calculated for Dab symmetry using symmetry adapted functions and a normalized spherical harmonic Hamiltonian. When the differences between calculated and observed band positions are minimized, the ligand-field and angular overlap parameters listed in Table 2 The study of electronic spectra has played a dramatic role in our understanding of the nature of the metal-ligand bonds in coordination complexes. Much effort has been concentrated in studying complexes of high symmetry, generally containing only one kind of ligand. Numerous models exist to convert these data into chemical information. They range from simple crystalfield models through more sophisticated ligandfield approaches and various molecular orbital methods ranging from ab initio to semi-empirical (1). Most of these methods can adequately describe the behaviour of molecules of high symmetry, but generally are of less utility with molecules of lower symmetry, a direct consequence of the increase in the number of parameters required to describe such systems. However, since the number of obse~vables also increases, generally, to a greater degree, this is not a serious drawback. Indeed, by using the extra Can. J. Chem. Downloaded from www.nrcresearchpress.com by 34.212.246.108 on 05/12/18For personal use only.

The single crystal electronic spectra of cis-octahedral nickel(II) diamine complexes at 10 K

“…The preparation of crystals and the methods employed to obtain spectra have also been previously reported (5,6,(15)(16)(17)(18) The complex Ni(s-Et,en),(NO,), (IV) has electronic spectroscopic features (see Fig. 1) very similar to those of the previously published nitrite complexes (14) suggesting that it also has a cis structure.…”

“…14). The utility of presenting such data obtained along orthogonal extinction axes has been discussed elsewhere (5). In general, with these low symmetry systems, the space groups frequently do not permit unambiguous assignments based solely on dichroism.…”

NiWO4 powders prepared via polymeric precursor method for application as ceramic luminescent pigments

“…Figure 4 shows the CIELab graphics of such NiWO 4 samples. The color of Ni 2+ -based compounds is directly influenced by the symmetry of its site [33]. The degeneracy of the 3 T 1g , 3 T 2g , and 3 E g states of Ni 2+ in octahedral geometry is lifted, and multiple-absorption bands occur when Ni 2+ is situated in a coordination environment of low symmetry.…”

“…The degeneracy of the 3 T 1g , 3 T 2g , and 3 E g states of Ni 2+ in octahedral geometry is lifted, and multiple-absorption bands occur when Ni 2+ is situated in a coordination environment of low symmetry. Bands split by low symmetry will show peak wavelengths, which are polarization dependent [33]. Bright yellow color results when Ni 2+ is in a deltahedric-coordinated site significantly distorted from the octahedral symmetry.…”

Study of Tetragonally Compressed Complexes of Fe(II), Ni(II) and Cu(II)

“…The electronic spectra of these complexes display four bands which may be assigned to = ν2, Table-5. The appearance of four bands is indicative of appreciable tetragonal deviation from octahedral symmetry while greater value of Dqz in respect of Dqxy and negative value of Dt confirm the tetragonal compression along Z-axis [35][36][37]. The magnetic moment and electronic spectral bands of Cu(II) complexes have been displayed in Table-6.…”