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Difference between revisions of "Absolute structure"

From Online Dictionary of Crystallography

(Background)
(Background)
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== Background ==
 
== Background ==
  
The above definition of ''absolute structure'' has been designed with the intent to show its similarities and differences with that of the IUPAC definition of [http://www.chem.qmul.ac.uk/iupac/stereo/A.html#01 ''absolute configuration'']: <br>
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Both the ''absolute structure'' of a crystal and the ''absolute configuration'' of a molecule describe the spatial arrangement of atoms in their respective object. However the object, its symmetry and the method of its specification are different. The table shows a  
''The spatial arrangement of the atoms of a chiral molecular entity (or group) and its stereochemical description''<br>
 
  
                absolute structure       absolute configuration
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                Absolute Structure       Absolute Configuration
object              crystal                   molecule
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Property      spatial  arrangement        spatial  arrangement
symmetry       non-centrosymmetric           chiral
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Content              atoms                      atoms
 
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Object              crystal                     molecule
 
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Symmetry       non-centrosymmetric               chiral
NOT FINISHED  NOT FINISHED NOT FINISHED
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Specification    crystallographic            stereochemical
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Specification      space group                    CIP
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                  cell dimensions
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                  atomic coordinates
  
 
== Related chemical terms ==
 
== Related chemical terms ==

Revision as of 10:18, 15 February 2006

Definition

The spatial arrangement of the atoms of a physically identified non-centrosymmetric crystal and its description by way of unit-cell dimensions, space group, and representative coordinates of all atoms.

Background

Both the absolute structure of a crystal and the absolute configuration of a molecule describe the spatial arrangement of atoms in their respective object. However the object, its symmetry and the method of its specification are different. The table shows a

                Absolute Structure        Absolute Configuration
Property       spatial  arrangement        spatial  arrangement
Content               atoms                       atoms
Object               crystal                     molecule
Symmetry        non-centrosymmetric               chiral
Specification     crystallographic            stereochemical
Specification       space group                    CIP
                  cell dimensions
                 atomic coordinates

Related chemical terms

The IUPAC Basic Terminology of Stereochemistry contains definitions of related chemical terms of use to the crystallographer, viz: absolute configuration, chiral, chirality, chirality sense, enantiomer, enantiomerically pure, enantiomorph, racemate, racemic, racemic conglomerate and relative configuration.