Crystal and molecular structure of 3-methyl-1-p-tolyltriazene

Crystals of the title compound have monoclinic symmetry with a= 8.196(1), b= 8.545(2), c= 13.163(2)A, β= 112.72(2)°, and space group P21/c. For 1 088 observed independent reflections collected on a four-circle diffractometer the R-factor reached 0.063 after full-matrix least-squares refinement. The triazene unit has a double bond between N(1)and N(2) with a hydrogen atom and a methyl group both carried by N(3). A 21–22° twist about the bond joining ring to triazene helps to relieve steric hindrance. Molecules are linked by N–H ⋯ N hydrogen bonding. The preference for the tautomeric form p-CH3·C6H4·NNH-CH3 in the solid state is consistent with the behaviour in solution, as determined by n.m.r. spectroscopy.