Rotational Barriers of Substituted BIPHEP Ligands: A Comparative Experimental and Theoretical Study

Abstract

The interconversion barriers of 14 different 3,3′‐ and 5,5′‐disubstituted tropos BIPHEP [2,2′‐bis(diphenylphosphino)‐1,1′‐biphenyl] and BIPHEP(O) [2,2′‐bis(diphenylphosphoryl)‐1,1′‐biphenyl] ligands were investigated by enantioselective dynamic high performance liquid chromatography (DHPLC) and DFT calculations using the B3LYP/6‐31G* and M06‐2X/6‐31G* levels of theory. The experimentally determined enantiomerization barriers varied from 86.8 to 101.4 kJ mol–1 and were found to be in excellent agreement with the calculated data. The root‐mean‐square deviations are 7.3 kJ mol–1 for the B3LYP functional and 11.3 kJ mol–1 for the M06‐2X method.