Open d shells

Two further consequences of the steric activity of open d shells are also important. One, which might seem somewhat circular but does not, in fact, involve any double counting , is that longer bonds are accompanied by smaller ligand-fields, that is, by... 

The driving force for Jahn-Teller distortions in transition-metal complexes is the open d shell. It is likely that explanations for them along the lines given above would have come about even if the theorem of Jahn and Teller had not been discovered. We make this remark not to denigrate that powerful piece of work, but as an attempt to defuse any mystery that might otherwise attach to OrgeTs application of that group-theoretical construction. 

We shall now look at a number of thermodynamic and structural variations in transition-metal compounds which owe their origins, at least in part, to the properties of open d shells. 

A minor success is also seen in complexes of d and d" ions, in which the distorted octahedral geometries observed may be rationalized (and indeed predicted) in terms of the Jahn-Teller effect, and ultimately in terms of the steric activity of the open d shell. This is a common feature in copper(n) chemistry, and you will... 

MOLECULAR MODELLING OF METAL COMPLEXES WITH OPEN d-SHELL... 

When it goes about metal carbonyls or about metals of the second or even third transition row, the DFT methods seem to be able to do the job quite decently. However, turning to compounds of the first transition row metals with open d-shells raises many problems. Intuitively distinction in behavior of two types of the metal compounds is clear to any chemist. In a row of... 

The latter is in relation with those proposed by Deeth [30] and Berne [155]. Both involve the d-shell energy as an additional contribution to that of the MM scheme and use the AOM model with interpolated parameters to estimate the latter. In the case of the approach [30] there are two main problems. First is that the AOM parameters involved are assumed to depend only on the separation between the metal and donor atoms. This is obviously an oversimplification since from the formulae Eq. (25) it is clear that the lone pair orientation is of crucial importance. This is taken into account in the EHCF/MM method. Second important flaw is the absence of any correlation in describing the d-shell in the model [30]. This precludes correct description of the switch between different spin states of the open d-shell, although in some situations different spin states can be described uniformly. 

Semiempirical method for transition metal complexes with open d-shells... 

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