pKaH values and θH angles of phosphanes to predict their electronic and steric parameters

Abstract

Phosphanes have numerous important uses and at the same time are an important class of organic bases with basicities spanning more than 30 orders of magnitude. In many cases, their behaviour in specific applications depends strongly on their basicity. Basicities (pKaH values) of many phosphanes have been published but are scattered across different reports and there are prominent gaps in the availability of data. In this report, we present an extensive set of pKaH data of a most diverse set of phosphanes, both newly measured/calculated and collected from the literature. We demonstrate that pKaH values can serve as an alternative to Tolman electronic parameters (TEP values) in evaluating the electronic properties of phosphanes. Additionally, we suggest two easily obtainable parameters for assessing the steric properties of phosphaneswithout need for sophisticated calculations or preparation of metal-ligand complexes.