Crystal and molecular structure of 1,2-dihydro-1-methyl-2-nitriminopyridine: X-ray and infrared studies

The crystal and molecular structure of 1,2 dihydro-1-methyl-2-nitriminopyridine (1) at 90.0(1) K have been determined. It crystallises in an orthorhombic Pna2(1) space group with a = 7.753(2), b = 13.829(3) and c = 6.070(1) Angstrom, Z = 4, R(F) = 0.0259 for 1856 unique reflections. The pyridine ring is planar, the N(1) nitrogen atom remains sp(2) hybridised. The NNO2 group is twisted 26 degrees along C-N bond and 15 degrees along N-N bond. The twist is caused by a steric hindrance and/or weak C-H ... O hydrogen bonds. LR spectra of (1), N-(2-pyridyl)-nitramine (4) and N-methyl-N-(2-pyridyl)-nitramine (9) were recorded in solution and in the solid state. The frequencies characteristic of the nitrimino group (1260 and 1436 cm(-1)) and the isomeric nitramine (1236 and 1536) differ markedly in the region of asymmetric stretching vibration. The spectra of (4) indicate that it exists in the nitrimino form in solution as well as in the solid state. (C) 1999 Elsevier Science B.V. All rights reserved.