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†

Comparison of the thermodynamic (logKHBwith 4-fluorophenol in CCI4, pKain azeotropic ethanol and GBin the gas phase) with spectroscopic basicities (ΔvOHof methanol in CCI4) for N1, N1-dimethylformamidines shows good correlation only between the pKaand ΔVOHvalues; no general simple linear model can be applied to the logKHB/ΔvOHand GB/ΔVOHrelations.