Carboranes as model hypercarbon systems; Structural and bonding patterns in selected isoelectronic closo-borane and carborane systems; [B_nH _n]~(2-), [1-CB_(n-1)H_n]~- and 1,n-C_2B_(n-2)H_n (n = 5, 6, 7, 10 or 12)

摘要

Computations have been carried out on the title boranes and carboranes, model hypercarbon cluster systems chosen to explore how effectively an individual carbon atom, whilst bonding by a normal 2-electron 2-centre bond to an exo-hydrogen atom, can also bond to sets of three, four or five equivalent boron atoms within a series of carborane clusters which have carbon atoms in axial sites of C_(3v), C_(4v) or C_(5v) local symmetry. The calculated interatomic distances and bond orders and CH and BH group charges are reported, and the manner in which the introduction of CH units to replace BH- units in closo-borane cages perturbs the distribution of the skeletal electrons in these clusters is discussed.