Cyclo-, Closo- and hypercloso-aminoboranes; B-B bonding, 3D-aromaticity, stability and NICS values

Abstract

Boron not only can form 2-center 2-electron bond, but also 3-center 2-electron and more complicated 4-center 2-electron bonds. This property of boron atom to form unusual B-B bonds causes to synthesis special and interesting aminoborane compounds. This review first highlights the major interesting advances to synthesis of closo-, hypercloso- and cycloaminoboranes and in the next portion describes stability and also aromaticity of these compounds through Nuclear Independent Chemical Shift (NICS) values that they are measured based on the amount of magnetic chemical shifts in the centers of the aromatic rings using quantum mechanical calculations. Benzene, as a planar aromatic structure has NICS: -9.7 but the calculated values of NICS for closo-B6(NMe2)6 with un-planar (3D aromatic) structure is −32.2.