Molecular double-bond covalent radii for elements Li-E112.

The previous systems of triple-bond and single-bond self-consistent, additive covalent radii, R(AB)=r(A)+ r(B), are completed with a fit for sigma(2)pi(2) double-bonds.The primary bond lengths, R, are taken from experimental or theoretical data corresponding to chosen group valencies. All r(E) values are obtained from the same, self-consistent fit. Many of the calculated primary data came from E=CH(2) and H-E=CH(2) models. Homonuclear LE=EL, formaldehyde-type Group 14-Group 16 and open-shell, X (3) Sigma Group-16 dimer data are included. The standard deviation for the 316 included data points is 3 pm.