Abstract:

The values of bond valence parameters R0 for the bonds of main group metal halides are usually obtained by systematic analysis of the crystal structure data by assuming B=0.037 nm. In this work, conversely, the values of B were proposed to be fitted with crystal structure data on assuming the values of R0 equal to the bond lengths of rg accurately determined by gaseous electron diffraction. As an example, the new sets of R0 /B for the Pb(II)—X (X=F, Cl, Br, I) bonds were obtained and fitted as 0.2036/0.0382, 0.2447/0.040, 0.2598/0.040, and 0.2804/0.0386, respectively. Compared with the values of R0=0.203, 0.253, 0.264, and 0.278 nm based on B=0.037nm for Pb(II)—X bonds reported in the literature, these new parameters were not only accurate and reliable for bond valence calculations, but also revealed the physical meaning inherent in every R0 as unit valence bond length.

Key words: Bond valence parameter, Bond length of unit valence, Electron diffraction, Pb(II) dihalide