(Solved): 22. The hydrogen bonding Lewis acid CHCl3 has a CH stretching frequency that is lowered u ...

22. The hydrogen bonding Lewis acid ${\mathrm{CHCl}}_3$ has a $\mathrm{C}?\mathrm{H}$ stretching frequency that is lowered upon deuteration. a. What is responsible for the theoretical factor of 1.4 ? b. What could be responsible if the observed factor were less than 1.4 ? c. When the compound is dissolved in the Lewis base ${\mathrm{NEt}}_3$, the $\mathrm{C}?\mathrm{H}$ stretching frequency is lowered. Rationalize the lowering. d. If one examines the $\mathrm{C}?\mathrm{D}$ shift upon adduct formation with ${\mathrm{Et}}_3\mathrm{N}$, the percentage lowering is smaller than that in (b). Rationalize this finding.