Is hydrogen electronegativity higher than Pauling’s value? New clues from the 13C and 29Si NMR chemical shifts of [CHF3] and [SiHF3] molecules

Abstract

Abstract We previously demonstrated that the δ NMR chemical shift of central NMR active atoms (A), in simple halido [AXn] (A=C, Si, Ge, Sn, Pb, Pt; Xn = combination of n halides, n = 4 or 6) derivatives, could be directly related to X radii overall sum, Σ(r L ). Further correlation have also been observed for tetrahedral [AX4] (A=C, Si; X4 = combination of four halides) compounds where the X Pauling electronegativities sum, Σ ( χ L Pau ) , $\Sigma (\chi _L^{{\rm{Pau}}}),$ exceeds a specific value (≈12.4). In this work, we focused on these latter systems considering the H vs. X substitution. The analysis of the literature reported δ(13C) and δ(29Si) NMR chemical shift for the mono hydrogenated derivatives and in particular for [CHF3] and [SiHF3], characterized by the lowest Σ(r L ) and the highest Σ ( χ L Pau ) , $\Sigma (\chi _L^{{\rm{Pau}}}),$ suggests a revised value for the H electronegativity ranking with respect to Pauling’s.