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International
Tables for Crystallography Volume G Definition and exchange of crystallographic data Edited by S. R. Hall and B. McMahon © International Union of Crystallography 2006 |
International Tables for Crystallography (2006). Vol. G. ch. 3.2, pp. 111-112
Section 3.2.4.5. Bond-valence information
a
School of Biomedical and Chemical Sciences, University of Western Australia, Crawley, 6009, Australia,bMerck Research Laboratories, Rahway, New Jersey, USA, and cInternational Union of Crystallography, 5 Abbey Square, Chester CH1 2HU, England |
Categories describing bond valences are as follows:
Data items in these categories are as follows:
![[Scheme scheme69]](/schemes/Gach3o2scheme69.gif)
![[Scheme scheme70]](/schemes/Gach3o2scheme70.gif)
The arrow (![[\rightarrow]](/teximages/abch3o1/abch3o1fi527.svg)
) is a reference to a parent data item.
The data items in this category group relate to bond valences, which are widely used in inorganic crystallography to confirm and analyse the results of crystal structure determinations. Bond valences are determined from the bond lengths and have the useful property that their sum around any atom is equal to the atom valence (formal charge). They are increasingly being published with bond lengths. The data item _geom_bond_valence in the GEOM_BOND category allows the bond valence to be associated with the bond length.
The two categories discussed here list the parameters used to calculate the bond valences and their literature sources. These items might also be published, particularly where there is some uncertainty about the appropriate parameters to use.
The data items in the VALENCE_PARAM category define the parameters used for calculating bond valences from bond lengths. In addition to the parameters, a pointer to the reference for the source of the parameters (in VALENCE_REF) is given (Example 3.2.4.16![[link]](/graphics/greenarr.gif)
).
![[Scheme scheme71]](/schemes/Gach3o2scheme71.gif)
