Crystal structures of 2,6-di-bromo-4-methyl-benzo-nitrile and 2,6-di-bromo-4-methyl-phenyl isocyanide.

In the title crystals, C8 H5 Br2 N, which are isomorphous, the steric bulk of the methyl group causes neighboring mol-ecules to become mutually inclined. This prevents the formation of planar or nearly planar sheets, which were observed in the tri-chloro and tri-bromo analogs. Instead of CN/NC⋯Br contacts, tetra-meric Br⋯Br contacts are observed. These contacts form tetra-gonally puckered sheets parallel to (001). The CN/NC and methyl groups are grouped at the peaks and troughs. Both mol-ecules lie across crystallographic mirror planes; thus, the methyl H atoms are disordered over two sets of sites with equal occupancy. The title nitrile is a redetermination. The refinement converged at R [ F 2 > 2σ( F 2 )] = 0.020, whereas the original determination [Gleason & Britton, (1976 ▸). Cryst. Struct. Commun. 5 , 229-232] had R = 0.112.