Crystal Structure of 2-(Ethoxymethylene)malononitrile and DFT Evaluation of the N-H···N≡C Close Contacts Energy

Introduction

Recently, we have synthesized 2-(ethoxymethylene)malononitrile 1 to reveal its crystal structure. This simply built compound is a very convenient building block for the construction of various heterocycles and it is assuming as an intermediate in different three-component reactions. In this study, we present the results of XRD of the titled compound demonstrating in crystal the linkage of the co-oriented molecules via N-H···N≡C non-covalent interactions. To evaluate the energy of such interactions, we conducted DFT simulations.

Experimental

The ¹H and ¹³C NMR spectra were recorded with a Varian (Agilent) 400 spectrometer. An XRD study of 1 was performed an Xcalibur Ruby diffractometer. Compound 1 was obtained by the known procedure. Coordinates from Xray data were used as initial and full geometry optimization of monomers and dimers were performed using DFT with different functionals and the 6-311++G(d,p) basis set.

Results and Discussion

The molecules of 1 are linked into infinite chains via N-H···N≡C close contacts with distance of 2.494(3) Å. When theoretical measuring the energy of H···N non-covalent interactions by DFT, it was determined by M06-2X functional equal to -1.20 kcal/mol meaning weak attraction.

Acknowledgments

This work was supported by the Russian Science Foundation (grant no. 22-23-00171 to VSG).