Estimation of the van der Waals radii of the d-block elements using the concept of bond valence

It is assumed that the valence v of the bond between a metal M and a non-metal X is negligibly small but not equal to zero when the distance between them is equal to the sum of their R values; the R value derived here for a d-block element with the Pauling RX values does not seem to depend on the oxidation state of M.