Ligand-field parameters and the stereochemical activity of d shells in trigonal-bipyramidal complexes of the first transition series

1985 ◽  
Vol 24 (26) ◽  
pp. 4490-4493 ◽  
Author(s):  
R. J. Deeth ◽  
M. Gerloch
Keyword(s):  
Ligand Field ◽  
Trigonal Bipyramidal ◽  
Transition Series ◽  
Ligand Field Parameters ◽  
Stereochemical Activity

Complexes of Dimethylaminophosphazenes with Metal Ions

1975 ◽  
Vol 53 (12) ◽  
pp. 1765-1774 ◽  
Author(s):  
H. P. Calhoun ◽  
N. L. Paddock ◽  
J. N. Wingfield
Keyword(s):  
Metal Ions ◽  
High Spin ◽  
Electronic Spectra ◽  
Molecular Structures ◽  
Metal Coordination ◽  
Ligand Field ◽  
Steric Interactions ◽  
Trigonal Bipyramidal ◽  
Ligand Field Parameters ◽  
Distorted Trigonal Bipyramidal

The preparation of complexes DDPN.2MCl2 (M = Mn, Fe, Co, Zn ), DDPN.M(NO3)2, (M = Mn, Co, Ni, Cu, Zn), (DDPN = N6P6(NMe2)12) ), and N9P9(NMe2)18.2CoCl2 is described. All the complexes of the hexamer are of the high spin type and contain the cations DDPNMX+ (X = Cl, NO3 ). Their infrared and electronic spectra show that their molecular structures are essentially the same as those established crystallographically for the chlorocations (M = Co, Cu ), in which, as a consequence of steric interactions, the metal has a distorted trigonal-bipyramidal environment. The complex with Cu(NO3)2 is exceptional in that the DDPNCu2+ ion is formed in ionizing solvents, with a change in the stereochemistry of the metal. Coordination localizes π-electrons in nitrogen, weakens the ring bonds, and strengthens the exocyclic P—N bonds, as expected theoretically. Approximate values of ligand field parameters of the Co(NO3)2 and Ni(NO3)2 complexes are similar to those of complexes formed by simple amines; the phosphazenes act as σ-donors, their acceptor levels not being used significantly.

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.

Ligand Field Parameters

1976 ◽  
Vol 15 (3-4) ◽  
pp. 189-199 ◽  
Author(s):  
Ivano Bertini ◽  
Dante Gatteschi ◽  
Andrea Scozzafava
Keyword(s):  
Ligand Field ◽  
Ligand Field Parameters

Thermodynamic of metal complexation of the macrocyclic antibiotic rifampicin

2001 ◽  
Vol 79 (1) ◽  
pp. 42-49
Author(s):  
I Shehatta ◽  
I Kenawy ◽  
A H Askalany ◽  
Ayman A Hassan
Keyword(s):  
Binding Sites ◽  
Equilibrium Constants ◽  
Ionic Species ◽  
Ligand Field ◽  
Water Medium ◽  
Acid Base ◽  
Distribution Diagram ◽  
Macrocyclic Antibiotic ◽  
Transition Series ◽  
Different Temperatures

The acid-base and complexation equilibria of rifampicin with H+, Mn2+, Co2+, Ni2+, Cu2+, Zn2+, Cd2+, Hg2+, and Pb2+ were studied by means of potentiometry. The stoichiometric equilibrium constants were determined in 50% (v/v) methanol-water medium at different temperatures and constant ionic strength (0.05 M KCl). It was established that rifampicin has two proton-binding sites. The distribution diagram of the corresponding ionic species as a function of pH is given and indicated that rifampicin exists predominantly in the zwitterionic form at pH [Formula: see text] 5. The thermodynamic parameters of protonation and complexation were derived and discussed. The formation of the complexes is spontaneous, more favourable at lower temperatures, entropically unfavourable, and an enthalpy-driven process. The order of the changes in Gibbs energy and enthalpy accompanying the complexation was found to be Mn2+ < Co2+ < Ni2+ < Cu2+ > Pb2+ > Zn2+ > Cd2+ > Hg2+ in accordance with the well-known sequence of Irving and Williams. The transition series contraction energy (Er(Mn-Zn)), and the ligand field stabilization energy (δH) were calculated from the enthalpy changes.Key words: rifampicin, thermodynamics, potentiometry, and complexation.

Ligand field stabilization energies and stereochemistry of early second and third row transition elements

1968 ◽  
Vol 21 (1) ◽  
pp. 9 ◽  
Author(s):  
R Colton ◽  
JH Canterford
Keyword(s):  
Periodic Table ◽  
Ligand Field ◽  
Transition Elements ◽  
Transition Series ◽  
Stabilization Energies

The elements of the second and third row transition series towards the left of the Periodic Table show clearly defined trends in their observed stereochemistries. These trends are summarized and an explanation for the experimental facts is suggested.

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