Capping and Decapping Series of Boranes

Whereas many of the capped series of carbonyl clusters of transition metals are known, those of corresponding borane series are unknown. These include the monocapped, bicapped, tricapped, tetracapped and so on. This paper attempts to correlate selected capped series of the carbonyl series with the hypothetical corresponding ones of boranes using 14n and 4n rules. Some selected examples of capped and decapped borane series have been generated and tabulated. The borane clusters are found to follow a precise numerical algorithm. A comparison of selected examples of carbonyl cluster of lower series such as closo, nido and arachno with the corresponding borane clusters has been made. The popularly cited Rudolph system of deducing shapes of clusters is also discussed in terms of decapping series. The use of fragments and their corresponding fragment series enormously simplifies the categorization of molecular formulas into series from which their shapes can be predicted with or without the use of the cluster number (k value). The fragment series vindicates the vital Hoffmann’s isolobal concept very well.