An imidazol-2-ylidene borane complex exhibiting inter-molecular [C–H(delta)+...H(delta)––B] dihydrogen bonds

The structure of 1,3-bis(2,4,6-trimethylphenyl)imidazol-2-ylidene·BH3, (1·BH3) has been determined by X-ray crystallography; the high melting solid exhibits head-to-tail alignment of the molecular dipoles in the solid state, with the closest intermolecular contact being a simple well-defined example of an unconventional [C–H(delta)+...H(delta)––B] dihydrogen bond.