Boron trichloride and mercuric cyanide react slowly to form the title compo
und, B2N2C2Cl8, which contains a four-membered B2N2 ring with alternating B
Cl2 and N = CCl2. Crystals are triclinic, space group Pi, a = 6.1198(1), b
= 7.4457(3), c = 7.9186(3) Angstrom, alpha = 117.064(2), beta = 106.923, ga
mma = 93.712(2)degrees, Z = 1, and V = 299.07(2) Angstrom(3). The compound
has a crystallographic center of symmetry but the metric symmetry is close
to the expected mmm.