Multinuclear NMR study of the crystal field strength of the nitro ligand and the empirical estimation of the cobalt-59 NMR chemical shifts of cobalt-nitro complexes

1990 ◽  
Vol 112 (21) ◽  
pp. 7482-7488 ◽  
Author(s):  
S. C. F. Au-Yeung ◽  
K. W. Kwong ◽  
R. J. Buist
Keyword(s):  
Field Strength ◽  
Crystal Field ◽  
Chemical Shifts ◽  
Empirical Estimation ◽  
Nmr Chemical Shifts ◽  
Multinuclear Nmr ◽  
Crystal Field Strength ◽  
Nitro Complexes ◽  
Nmr Study

The crystal field strength of the nitro ligand and the chemistry of the hexanitrocobaltate(III) anion

1985 ◽  
Vol 63 (12) ◽  
pp. 3558-3567 ◽  
Author(s):  
Richard J. Buist ◽  
Steve C. F. Au-Yeung ◽  
Donald R. Eaton
Keyword(s):  
Electron Transfer ◽  
Field Strength ◽  
Crystal Field ◽  
Strong Field ◽  
Chemical Shifts ◽  
Spectroscopic Properties ◽  
Nitrite Ion ◽  
Electron Transfer Mechanism ◽  
Spontaneous Reduction ◽  
Crystal Field Strength

The chemical and spectroscopic properties of the hexanitrocobaltate(III) anion are not in accord with the classification of the N-bonded nitrite ion as a strong field ligand. The nitro groups are rapidly displaced by other ligands, including water, and in dilute aqueous solution spontaneous reduction to Co(II) occurs. Comparison of solid state and solution vibrational and 59Co nmr spectra demonstrates that the principal species in solution is the same as in the solid. All ligands are N-bonded. However, within 2 or 3 min of dissolution new species appear. An electron transfer mechanism for ligand exchange is suggested. It is shown that the band at 480 nm arises from the first d–d transition of the pentanitroaquacobaltate(III) ion and not from a hexanitrocobaltate(III) transition. The composition of the aged solutions has been studied by 59Co, 14N, and 17O nmr. At least 10 different species are apparent in the 59Co spectra. They have been assigned to mixed nitro/nitrito/aqua ions. Electron transfer can also lead to the formation of Co2+ and NO3−, ions, both ions being detected by 14N and 17O nmr spectroscopy. The Co complexed nitro ligand has been detected for the first time in the 14N nmr spectrum. Analysis of 59Co chemical shifts shows that the crystal field strength of the nitro ligand falls steadily with the number of nitro groups in the molecule. The cis groups are four times more effective than the trans groups in causing this change. The cyano ligand shows the opposite behaviour — the crystal field strength increases with substitution and trans groups have a larger effect than cis groups. The reactions of the hexanitrocobaltate(III) ion with ethylenediamine and with cyanide ions have been studied by 59Co nmr. Mixed nitro complexes are formed with ethylenediamine but mixed nitrito complexes predominate with cyanide.

scholarly journals A 195Pt NMR study on zero-magnetic-field splitting and the phosphorescence properties in the excited triplet states of cyclometalated platinum(ii) complexes

2020 ◽  
Vol 49 (19) ◽  
pp. 6363-6367
Author(s):  
Soichiro Akagi ◽  
Sho Fujii ◽  
Noboru Kitamura
Keyword(s):  
Magnetic Field ◽  
Metal Complexes ◽  
Chemical Shifts ◽  
Zero Magnetic Field ◽  
Triplet States ◽  
Field Splitting ◽  
Excited Triplet ◽  
Nmr Chemical Shifts ◽  
Nmr Study ◽  
Excited Triplet States

The strength of zero-magnetic-field splitting in the excited triplet states of metal complexes is reflected in the metal NMR chemical shifts.

scholarly journals Luminescence properties of Ce3+ and Eu2+ in fluorites and apatites

Mineralogia ◽  
2009 ◽  
Vol 40 (1-4) ◽  
pp. 85-94 ◽  
Author(s):  
Sabina Bodył
Keyword(s):  
Field Strength ◽  
Crystal Field ◽  
Luminescence Properties ◽  
Luminescence Spectra ◽  
Low Concentration ◽  
Crystal Field Strength

Luminescence properties of Ce3+ and Eu2+ in fluorites and apatitesNatural samples of fluorite and apatite from granites, pegmatites, carbonatites and andesitic tuffs were investigated by steady-time spectroscopy to characterize the luminescence properties of Ce3+ and Eu2+. The luminescence of Ce3+ has been clearly seen in fluorite as 320 and 337 or 343 nm bands. In apatites, two distinct bands for two different Ca crystal sites were obtained: 340-380 nm for Ca(1) and 420-450 nm for Ca(2). The luminescence spectra of Eu2+ in the fluorite crystals were measured even at for low concentration of this element (0.11 ppm). For Ce3+, it has been showed that the crystal field strength depends more on the nature of the ligand than on the Me-ligand distances.

scholarly journals A multinuclear NMR study of some cyclic phosphonic diamides

1994 ◽  
Vol 12 (1) ◽  
pp. 31-34
Author(s):  
Wojciech Bocian ◽  
Lech Stefaniak ◽  
Graham A. Webb
Keyword(s):  
Molecular Structure ◽  
Chemical Shifts ◽  
Multinuclear Nmr ◽  
Nmr Data ◽  
Nmr Study ◽  
Sensitive Parameters

1H,13C,15N and31p NMR data are presented for four cyclic phosphonic diamides. In tenns of useful structural infonnation it is found that the31p chemical shifts and1J(31P_15N) couplings are the most sensitive parameters to variations in molecular structure.

Intentional modification of the optical spectral response and relative sensitivity of luminescent thermometers based on Fe3+,Cr3+,Nd3+ co-doped garnet nanocrystals by crystal field strength optimization

2020 ◽  
Vol 4 (6) ◽  
pp. 1697-1705 ◽  
Author(s):  
K. Kniec ◽  
K. Ledwa ◽  
K. Maciejewska ◽  
L. Marciniak
Keyword(s):  
Field Strength ◽  
Crystal Field ◽  
Spectral Response ◽  
Relative Sensitivity ◽  
Temperature Range ◽  
Crystal Field Strength ◽  
Co Doped

The relative sensitivity and usable temperature range of Fe3+,Cr3+-based luminescent thermometers can be tuned by modification of the crystal field strength.

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