Ligand field spectra of square-planar platinum(II) and palladium(II) complexes

1981 ◽  
Vol 20 (3) ◽  
pp. 796-800 ◽  
Author(s):  
L. G. Vanquickenborne ◽  
A. Ceulemans
Keyword(s):  
Ligand Field ◽  
Square Planar ◽  
Ligand Field Spectra

Copper(II) complexes of o-hydroxyarylcarbonyl compounds

1968 ◽  
Vol 21 (3) ◽  
pp. 617 ◽  
Author(s):  
DP Graddon ◽  
GM Mockler
Keyword(s):  
Solid State ◽  
Chelate Ring ◽  
Magnetic Moments ◽  
Equilibrium Constants ◽  
Ligand Field ◽  
Infrared Band ◽  
Planar Structures ◽  
Square Planar ◽  
Inductive Effects ◽  
Ligand Field Spectra

A series of copper(11) complexes has been prepared of the type CuL2Bn, where L is an o-hydroxy-aryl-, or naphthyl-, aldehyde, ketone, or ester, B is water or 4-methylpyridine, and n = 0, 1, or 2. All these complexes have a strong infrared band in the region 1600-1660 cm-l, showing that the oxygen atoms in the chelate ring are non-equivalent ; their magnetic moments fall in the range usual for copper(11) compounds. Equilibrium constants determined for the addition of one molecule of 4-methylpyridine to the anhydrous compounds in chloroform solutions fall in the range 0.5 < k < 40 and are comparable to the constant for the addition of 4-methylpyridine to bis(acetylacetonato)copper(11) (b 2.7). Increased stability of the adducts can be associated with the inductive effects of ligand substituents. Ligand field spectra in the solid state and in solution closely resemble those of corresponding bis(acetylaoetonato)copper(11) complexes and provide evidence for square-planar structures of the anhydrous complexes and square-pyramidal structures of the 1 : 1 adducts with 4-methylpyridine or water. No evidence is available for the structures of 1 : 2 adduots which may be formed in solutions in 4-methylpyridine; these solutions are unstable, but the nature of the slow reactions which occur in these solutions is not known.

scholarly journals Complex Formation Between Imidazole and Nickel(II) Salts

1974 ◽  
Vol 29 (7-8) ◽  
pp. 527-531 ◽  
Author(s):  
J. C. Jansen ◽  
J. Reedijk
Keyword(s):  
Complex Formation ◽  
Infrared Spectra ◽  
Coordination Compounds ◽  
Tetragonal Symmetry ◽  
Ligand Field ◽  
X Ray ◽  
Square Planar ◽  
Ligand Field Spectra ◽  
Crystal Field Parameters ◽  
Imidazole Compounds

Coordination compounds of formula Ni(Iz)nX2(H2O)m, in which Iz=imidazole, n = 1, 2, 4, 6, m = 0-4, and X = Cl-, Br-, I- and NCS-, are described. The anhydrous compounds are prepared from ethanolic solutions of Iz and nickel(II) salts in stoichiometric amounts in the presence of the dehydrating agent triethylorthoformate. Without this dehydrating agent hydrates are isolated for n = 2,4 and 6 with X = Cl, Br.The compounds were identified by means of infrared spectra (4000-25 cm-1), ligand-field spectra (35000-4000 cm-1) and X-ray powder diagrams. Compounds of formula [Ni(Iz)6]X2 all contain octahedrally coordinated Ni2+, for which the spectrochemical parameters were obtained. Tetragonal Ni2+ ions occur in [Ni(Iz)4X2] in which X = Cl and NCS, and in [Ni(Iz)4(H2O)2]X2 in which X = Cl and Br. These compounds are paramagnetic and the crystal-field parameters for tetragonal symmetry have been calculated. In [Ni(Iz)4]X2 with X = I and Br, the Ni2+ ions are square-planar coordinated with anions in the second coordination sphere, resulting in orange-coloured diamagnetic compounds.Anion-bridged distorted octahedrally coordinated Ni2+ ions probably occur in the compounds of formula Ni(Iz)2X2, in which Iz takes the axial positions. Similar structures are suggested for the mono-imidazole compounds, NiIzX2.

The Coordination Chemistry of Phosphoryl Compounds Containing the — N(CH3)2 Group, Part VIII

1972 ◽  
Vol 27 (7) ◽  
pp. 759-763 ◽  
Author(s):  
M. W. G. De Bolster ◽  
W. L. Groeneveld
Keyword(s):  
Coordination Chemistry ◽  
General Formula ◽  
Ligand Field ◽  
Chemical Analyses ◽  
X Ray ◽  
Physical Measurements ◽  
Ligand Field Spectra ◽  
Chloride Adduct ◽  
Ligand Field Parameters ◽  
Group Part

A number of new solvates and adducts containing bisphenyldimethylaminophosphine oxide is reported. The solvates have the general formula M[(C6H5)2P(O)N(CH3)2]42+(anion-)2, in which M = Mg, Ca, Mn, Fe, Co, Ni, Cu, Zn and Cd, and the anions are ClO4- and BF4-. The adducts have the general formula M[(C6H5)2P(O)N(CH3)2]2Cl2, where M stands for the same series of metals.The compounds are characterized and identified by chemical analyses and physical measurements.Ligand-field and vibrational spectra have been investigated; values for the ligand-field parameters are reported. It is concluded that coordination takes place via the oxygen atom of the ligand.X-ray powder patterns were used in combination with ligand-field spectra to deduce the coordination around the metal ions.The interesting behaviour of the nickel (II) chloride adduct upon heating is discussed and it is shown that both a square pyramidal and a tetrahedral modification exists.

Unusual ligand field effects in square-planar cobalt(II) complexes of quadridentate Schiff bases

1985 ◽  
Vol 24 (8) ◽  
pp. 1159-1165 ◽  
Author(s):  
A. Ceulemans ◽  
M. Dendooven ◽  
L. G. Vanquickenborne
Keyword(s):  
Schiff Bases ◽  
Ligand Field ◽  
Field Effects ◽  
Square Planar

Cobalt-59 NMR chemical shifts of cobalt(III) complexes; correlations with parameters calculated from ligand-field spectra

1985 ◽  
Vol 107 (9) ◽  
pp. 2780-2787 ◽  
Author(s):  
Richard Bramley ◽  
Michael Brorson ◽  
Alan M. Sargeson ◽  
Claus E. Schaeffer
Keyword(s):  
Chemical Shifts ◽  
Ligand Field ◽  
Nmr Chemical Shifts ◽  
Ligand Field Spectra

The ligand field spectra of trinuclear chromium(III) and iron(III) basic acetates

1969 ◽  
Vol 22 (4) ◽  
pp. 701 ◽  
Author(s):  
L Dubicki ◽  
RL Martin
Keyword(s):  
Field Theory ◽  
Ligand Field ◽  
Ligand Field Theory ◽  
Visible Spectra ◽  
Ligand Field Spectra

The visible spectra of trinuclear chromium(III) acetates [Cr3O(CH3CO2)6R2]+ can be successfully analysed by means of the ligand field theory for tetragonal fields. The ligands R (R = H2O, NH3, py, DMSO) are relatively labile and may be replaced by several ligands of varying donor strength. The spectra of trinuclear iron(III) acetates [Fe3O(CH3CO2)6R3]+ are poorly resolved but can be interpreted on the basis of a d5 configuration in octahedral fields.

Cobalt(II), nickel(II) and copper(II) complexes of some 2'-hydroxychalcones

1980 ◽  
Vol 33 (4) ◽  
pp. 737 ◽  
Author(s):  
M Palaniandavar ◽  
C Natarajan
Keyword(s):  
Infrared Spectra ◽  
Metal Ion ◽  
Magnetic Moments ◽  
Phenyl Group ◽  
Ligand Field ◽  
Square Planar ◽  
Spin Pairing ◽  
Square Configuration ◽  
Electron Sink ◽  
Octahedral Configuration

Metal(II) bis-chelates of the type ML2 [M = CoII, NiII, CuII; L = 2'- hydroxy-5'-X-chalcone where X = H, CH3, Cl] have been prepared and studied. Structures have been assessed by the measurement of magnetic moments, ligand field and infrared spectra and thermal properties. These chelates possess low-spin trans-square-planar configuration and show resistance to adduct formation in contrast to metal(II) chelates of β-diketones, salicylaldehyde, o-hydroxyaryl ketones and esters and o-hydroxy-crotonophenones, which have high-spin octahedral configuration. Extensive conjugation lowers the energy of the π3* orbital which enters into a very strong dπ-π3* interaction leading to spin-pairing. ��� Infrared spectra indicate that the carbonyl group is perturbed only slightly by coordination to metal. A change in metal ion affects v(C=O), v(M-O) and other vibrations and the order of stability, namely, Co ≈ Ni < Cu, inferred from these vibrations is as expected for the low-spin square configuration of the chelates. Introduction of substituents (5'-X) alters only v(M-O) significantly and the order of stability, namely, Cl > CH3 > H, derived from v(M-O) is consistent with Taft's resonance polar parameters of the substituents. All these observations are explained by the electron sink property of the phenyl group.

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