Adhikesavalu, D., Kamath, N.U. & Venkatesan, K. Proc. Indian Acad. Sci. (Chem. Sci.) (1983) 92: 449. doi:10.1007/BF02839148
From structural data of several crystal structure analyses of push-pull ethylenes it is found that C=C bond lengths in this class of molecules are significantly longer than the value for this bond in ethylene. With powerful donors and acceptors such as -NMe2 and -COOMe groups respectively, the C=C bond length is as long as 1.460 å. Correlations are observed between (i) C=C bond lengths and the twist angles about the C=C bond and (ii) C=C bond lengths and the torsional barrier measured by thednmr technique.
X-ray structure analysispush-pull ethylenesC=C bond lengthsrotational barriers