Crystal structure of 2-cyano-2-[3-cyano-4-diethyl-amino-1H-quinolylidene-2]-N,N-diethylacetamide,C21H25N5O

Crystals of the title compound, C₂₁H₂₅N₅O, are monoclinic: space groupP2₁/c,a = 12·680,b = 11·844,c = 13·550 Å, = 104·13 °,Z = 4. The structure was determined with CuK diffractometer data by direct methods and was refined by full-matrix least-squares methods toR = 0·076 for 2340 observed reflexions. All non-methyl hydrogen atom positions were determined. The hydrogen atom which is bonded to the ring nitrogen atom forms an intramolecular hydrogen bond with the carbonyl oxygen atom. Neither the six-membered homocyclic ring nor the six-membered heterocyclic ring is exactly planar. The molecular geometry and the detailed bond distances suggest that electron delocalization into the side chains is stabilized by the intramolecular hydrogen bond. This molecular structure determination has aided in the formulation of a reaction path for the 21 addition of cyano ynamine to phenylisocyanate.We thank Dr. M. E. Kuehne for suggesting the problem and for crystals, the National Research Council of Canada for financial support, and the University of British Columbia Computing Centre for assistance.