HF 0 0.14-0.34 0 H n-ChHI1 0 2.39-0.15 0-__'Substituent parameters were obtained from ref 6. bii values for these groups were divided by 2 to give values for meta and para positions. data set has a R that is not less than or equal to 0. As a consequence, most para substituted compounds display a decrease in binding affinity for the enzyme. This equation has a correlation coefficient 15% higher than the equivalent equation with up in place of R. The ...