Comparison of Thermodynamic Hydrogen Bonding, Brönsted and Gas-phase Basicity with Spectroscopic Hydrogen Bonding Basicity of N1,N1-Dimethylformamidines. Similarities and Differences in Substituent Effects

Abstract

Comparison of the thermodynamic (logK_HB with 4-fluorophenol in CCl₄, pK_a in azeotropic ethanol and GB in the gas phase) with spectroscopic basicities (Δv_OH of methanol in CCl₄) for N¹,N¹-dimethylformamidines shows good correlation only between the pK_a and Δv_OH values; no general simple linear model can be applied to the logK_HB/Δv_OH and GB/Δv_OH relations.