The structures and thermodynamic properties of imidochloroboranes (ClBNE)(n) (n = 1-16) have been investigated theoretically at the B3LY-P/6-31G* level of theory. Needle-shaped oligomers that violate the 'isolated square rule' are found to be more stable than cage isomers. Generation of the gas-phase (ClBNH), clusters is favorable thermodynamically starting from BCl3 and NH3. This makes these species possible intermediates involved in the gas-phase generation of BN nanoparticles. (c) 2006 Elsevier B.V. All rights reserved.