Abstract

Enos Masheija Kiremire

DOI : http://dx.doi.org/10.13005/ojc/310301

The paper attempts to explain at length the close relationship between transition metal carbonyl clusters with main group clusters especially the boranes using the 14n and 4n rules. When the ‘shielding’ electrons are removed from a transition metal carbonyl cluster and becomes ‘naked’, it resembles a corresponding one in the main group elements. A an expanded table of osmium carbonyl clusters was constructed using the capping fragment Os(CO)₂(14n-2) and the fragment Os(CO)₃ (14n+0). The table reveals the fact that the known series such closo, nido and arachno are part and parcel of a wide range of series especially the capping series 14n+q, where q  takes up negative multiple integers of two including 0 such as such = 0, -2,-4, -6, and so on. The linkage between capping series in transition metal carbonyl clusters has also been identified. Apart from the capping series generated in the table, there is another type of series where the skeletal cluster elements remained the same but the number of carbonyl ligands successively decreased. These types of series are referred to as stripping series. Mapping generating functions were also derived which produces any cluster formula or series required. Also the table shows that many clusters form utilizing some of its atoms as closo nucleus around which the larger ones are built and thus forming  clusters within  larger clusters. The table may be used to categorize a given cluster formula that falls within its range. Otherwise, using the 14n rule or 4n rule can be used for cluster classification. Furthermore, the table indicated that atoms, fragments and  molecules can be classified into series. Through this approach of using series, Hoffmann’s important isolobal relationship of chemical species can splendidly be explained.Using the 14n rule and 4n rules creates a framework under which chemical species such as  atoms, fragments, molecules and ions some of which may appear unrelated from main group elements and transition metal  may be grouped together like ‘birds of a feather flock together’ provided the skeletal elements obey octet or eighteen electron rule.

Beads; Necklaces; attempts; explain

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