Crystal Structure of 2-(Ethoxymethylene)Malononitrile, Hirshfeld Surface Analysis and DFT Evaluation of the Non-covalent Interactions Energy

The presented study describe the crystal structure of 2-(Ethoxymethylene)malononitrile (1), C₆H₆N₂O, in the monoclinic space group P2₁/m with Z = 2, a = 6.798(3), b = 6.172(3), c = 8.844(5) Å. The unit cell of a single crystal of 1 contains two antiparallel oriented molecules. Ethyl fragment demonstrates a disorder with equal occupancy values of 0.5 and a total site-occupation factor (s.o.f.) of 1.0. The molecules of 1 are linked into infinite chains of co-oriented molecules parallel to the a axis via N-H···N ≡ C close contacts with the distance of 2.494(3) Å. There are also weak hydrogen bonds > O···H- between the oxygen atom and the ethyl moiety. The estimation of the energy of non-covalent interactions was conducted by DFT method with different functionals. The best reproducibility of the geometric parameters of those interactions was obtained by using M06-2X functional. The estimated energy value was found to be − 1.20 kcal/mol.