Hydrogen bonding probes electron density variations at the basic center in substituted alkyl benzoates: Theory and experiment.

Theoretical computations of charge density parameters are juxtaposed to experimental spectroscopic shifts induced by hydrogen bonding for a series of 21 substituted in the aromatic ring ethyl and methyl benzoates. Strong correlations between atomic charges at the proton accepting atom and the shifts of methanol O-H frequencies are established. Hirshfeld, Charge Model 5 (CM5), and natural population analysis (NPA) atomic charges are evaluated using B97X-D/6-311++G(3df,2pd) and MP2/6-311++G(3df,2pd) computations. The results obtained reveal the power of hydrogen bond measurements in characterizing the variations of electron densities at the proton accepting center within a series of structurally related molecules. The limits of application of the approach are outlined. [ABSTRACT FROM AUTHOR]