Volume 1 Chapter 1 Introduction

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1.2 The Cambridge Structural Database (CSD)

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 compounds containing up to ca. 500 atoms (including hydrogens).

The CSD is fully retrospective (earliest reference with coordinates is 1936), and is updated on a current and continuing basis. Some 10,000 new entries are added in each calendar year. All information entering the CSD is subject to computerised check and evaluation procedures and to thorough visual proofing.

The major source of information is the primary literature and all coordinate sets that have been deposited in secondary deposition documents are also routinely obtained and included. The CSD also acts as a depository in its own right for a number (35) of major journals and direct deposition agreements are being discussed with a number of other publishers.

An entry in the CSD relates to an individual publication of a specific crystal structure: papers reporting a number of crystal structures will generate that number of CSD entries.

Each entry is identified by a CSD Reference Code (REFCODE) which identifies the chemical compound and its publication history.

The information content of each entry is conveniently summarized by the three major subdivisions in the diagram below:

Obviously, the 3D information can be used, in conjunction with a set of covalent radii, to establish a 'crystallographic' connection table. In the Version 5 database, the chemical and crystallographic connectivities are unified for the first time. This now permits the integrated 2D/3D substructure search mechanism now included in the graphics software system.

The CSD also contains a number of derived information fields, principally an extensive bit-map describing the presence/absence of specific information on a yes/no (1/0) basis. These bit settings, or screens, are used to speed many searches in both the basic and graphics software systems. Certain of these bit settings can be used as search keys in their own right.

The reference code system, and a detailed description of CSD information content is given in chapter 2 of this Volume. A full and complete discussion of connectivity representations is provided in chapters 2, 6 of this Volume and in chapter 5 of Volume 4.

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Volume 1 Chapter 1 A Statistical Survey.