The cyanocarbonyl group: synthesis and crystal structure of an imidazole carbonyl cyanide, C12N5OH17

1-t-Butyl-5-N-(dimethylaminomethylene)aminoimidazole-4-carbonyl cyanide (BU NDAMIC) is the first acyl cyanide to be synthesized from an imidazole-4-car boxylic acid, diethylphosphorocyanidate, and triethylamine and its structur e determined by x-ray crystallography. It crystallizes with four molecules in the monoclinic space group (C) under bar 2/(m) under bar with a = 17.824 (2), b = 6.784(2), c = 11.039(2) Angstrom, and beta = 96.17(1)degrees; (R) under bar = 0.036 over 1086 unique x-ray reflections. The cyanocarbonyl gro up is nearly linear, C-C = N angle 174.4(3)degrees, with dimensions C = N, 1.137(3); C-C, 1.493(3); and C = O, 1.224(3) Angstrom. The imidazole ring, in the mirror plane, has a lengthened C4 = C5 bond of 1.421(3) Angstrom, an d there is a short ring-closing approach, H ... O6 = 2.07 Angstrom, between the methyleneamino hydrogen and the carbonyl oxygen.