Cambridge Crystallographic Database description

Structural evidence culled from the Cambridge Crystallographic Database have been incorporated where possible. The original stereochemical models have been reproduced, even those that have been improved by subsequent evidence. In many instances, a detailed description of the course of these processes is still lacking. Nowhere is this lack of information more striking than in the Cu(I) catalyzed cyclo-propanation of alkenes. 

In the following sections, our first-principles bottom-up methodology will be described from a physical perspective (a full description on mathematical terms can be found in Ref. [7]). Then, the use of this methodology will be illustrated on the a-2-hydro nitronyl nitroxide [8] (hereafter called a-HNN), the simplest member of the nitronyl nitroxide family (R = H in Figure 1). The macroscopic magnetic properties and crystal structure of this compound are well known (its crystal structure is stored in the Cambridge Crystallographic Database [9] with refcode name TOLKEK). 

Examples of the second technique are Beilstein (currently with SANDRA on PC), MACCS (for storage and retrieval of structural data) and DARC-SMS (for storage and retrieval of structural data). Both MACCS and DARC-SMS can be coupled with general Database Management Systems (ORACLE, 1032) to store descriptive data. Other examples are CCSD, the Cambridge Crystallographic Database, PDB, the Brookhaven... 

This review covers the 2000 hterature of carboranes and metallacarboranes and follows essentially the same format as adopted in previous years. Selected heteroboranes of the other members of Group 4 (e.g. Sn) are also included. Carborane complexes are ordered by their formula, with metal complexes included in a separate, appropriately ordered, section. Those complexes with both a carbon and another heteroatom in the cage have been included in the appropriate section on the basis of the carbon atom count. Exo metalla-sub-stituted carboranes are included in the appropriate carborane section. The literature pubhshed has been searched using Web of Science, CAS and the Cambridge Crystallographic Database. Due to space hmitations, descriptions of specific results are kept to a minimum, with the reader directed to the original paper for more information. 

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