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1.2 Information Content of the Cambridge Structural Database

Organic and Metallo-organic Structures

The CSD records bibliographic, 2D chemical and 3D structural results from crystallographic analyses of organics, organometallics and metal complexes. Both X-ray and neutron diffraction studies are included for small and medium-sized compounds containing up to ca. 500 atoms (including hydrogens).

The CSD is fully retrospective and is updated on a current basis. About 12,000 new entries were added in 1993. All information is abstracted from the primary literature and associated supplementary publications; the CCDC acts as the official depository for unpublished coordinate information for over 30 journals. All information entering the CSD is subject to computerized check and evaluation procedures.

Entries and Reference Codes (Vol.1, p.2-4)

A CSD entry relates to an individual publication of a specific crystal structure: papers reporting n crystal structures will generate n CSD entries.

Each CSD entry is identified by a CSD Reference Code (refcode) which identifies the chemical compound (six letters) and its publication history (two additional digits).

The second digit identifies supplementary studies of the compound e.g. by a different research group, in a different polymorph, by different radiations, at different temperatures, etc.

The first digit refers to the publication history of each study by a given research group: zero indicates the initial paper, maybe a short note, 1, 2 .... indicate later publications of the same supplementary study.

Information Content of a CSD Entry

It is convenient (Figure 1) to categorize the information content of the CSD as:

1D Information: Text and Simple Numerical Items

2D Information: Chemical Structural Diagram as a Connection Table

3D Information: Crystal Structure Description

Protein Structures in the CSD

Since October 1993, information from the Protein Data Bank is being formatted for inclusion in the CSD files. The current status of this work, and the search facilities currently provided, are detailed in Section 3.7 of this Guide. Future developments in this area will be announced through the on-line documentation in the CSD System and through Newsletters issued periodically by the CCDC.

Figure 1

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