Polar and steric effects in the stability of silver complexes of primary amines
Abstract
The complex-formation constants of alkylamines NRH2 with AgI have been determined at 25 °C and I= 0.1 mol dm–3, the background salt being mainly [NRH3][NO3]. The pKa, logK1, and logβ2 valuee are: R = Me, 10.64, 3.06, 6.78; Et, 10.66, 3.44; 7.34; Pri, 10.62, 3.64, 7.77; But, 10.66, 3.69, 7.87; Bu8, 10.56, 3.65, 7.77; cyclopropyl, 9.06, 3.10, 6.43; cyclopentyl, 10.63, 3.61, 7.83; and cyclohexyl, 10.62, 3.72, 8.02. It is shown that these variations of pKa and logK can be readily understood in terms of Taft's (1957) equation relating formation and rate constants to polar and steric effects. Correlations from this equation suggest that Ag+ is much less susceptible to steric hindrance than is the proton.