MO study of Td-D4h equilibrium in complexes of transition metals. II. Equilibrium in tetrafluoro and tetrabromo complexes of atoms of the first transition row

1984 ◽  
Vol 49 (12) ◽  
pp. 2837-2856 ◽  
Author(s):  
Peter Pelikán ◽  
Marek Liška
Keyword(s):  
Electronic Structure ◽  
Transition Metals ◽  
Central Atom ◽  
Spin States ◽  
Cndo Method ◽  
Oxidation Degree ◽  
High Spin States ◽  
Square Planar ◽  
Complexes Of Transition Metals ◽  
Square Planar Complexes

The CNDO method for transition metals in the UHF version has been used to study the equilibrium of configuration isomers of tetrahedral and square-planar tetrafluoro and tetrabromo complexes of the first transition row atoms in the oxidation degree II (Mn(II), Fe(II), Co(II), Ni(II), Cu(II) both in low-spin and in high-spin states. The results show that the ability (given by electronic structure of the central atom) to form the square-planar complexes decreases monotonously in the series: Mn(II) > Fe(II) > Co(II) > Ni(II) > Cu(II). With respect to the effect of the electronic structure of ligands, the same ability decreases in the series: F- > Cl- > Br-.

MO study of Td-D4h equilibrium in complexes of transition metals. Equilibrium in tetrachloro complexes of atoms of the first transition row

1982 ◽  
Vol 47 (6) ◽  
pp. 1556-1569 ◽  
Author(s):  
Petr Pelikán ◽  
Marek Liška
Keyword(s):  
Experimental Data ◽  
Electronic Structure ◽  
Chemical Reactions ◽  
Central Atom ◽  
Equilibrium Constants ◽  
Cndo Method ◽  
Oxidation Degree ◽  
Square Planar ◽  
Complexes Of Transition Metals ◽  
Square Planar Complexes

The CNDO method in UHF version has been used for study of equilibrium of configuration isomers of tetrahedral and square-planar tetrachloro complexes of the first transition row atoms in the oxidation degree II (Mn(II), Fe(II), Co(II), Ni(II), Cu(II)). From the results it follows that the ability (conditioned by electronic structure of the central atom) to form the square-planar complexes decreases in the series Mn(II) > Fe(II) > Co(II) > Ni(II) > Cu(II). Several authors state the fact that the most important task of quantum chemistry is to develop procedures for calculation of rate and equilibrium constants of chemical reactions1,2. At the same time it is emphasized that these procedures should be independent of experimental data. By this term the authors mean such experimental data which are in some way connected with the reaction studied, and not the general experimental experience which (after transformation into axioms) can represent a basis of the used method.

π-BONDING IN INORGANIC COMPOUNDS: II. THE TRANSMISSION OF ELECTRONIC EFFECTS THROUGH SQUARE-PLANAR COMPLEXES

1961 ◽  
Vol 39 (2) ◽  
pp. 324-330 ◽  
Author(s):  
A. D. Westland ◽  
L. Westland
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Central Atom ◽  
Inorganic Compounds ◽  
Electron Drift ◽  
Electronic Effects ◽  
Trans Effect ◽  
Pyridine Ligands ◽  
Square Planar ◽  
In Trans ◽  
Square Planar Complexes

Measurement of the transmission of electronic effects through square-planar complexes of platinum has provided evidence of double bonding to halogen and nitro ligands. The nuclear magnetic resonance chemical shift of the β-protons in pyridine ligands serves as an indicator of electron drift in the complexes. Justification is thus provided for the assumed mechanism of the trans effect involving π-bonding. The observations are in accord with the assumption that the increase in trans-directing powers with atomic number of the halogen is due to an increasing tendency to accept d-electrons from the central atom.

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