CONE ANGLE RADIAL PROFILES

Various methodologies have been reported in the literature for the eva luation of the size of a ligand or organic functional group, with the Tolman cone angle methodology proving to be most popular in inorganic chemistry. A procedure to extend the Tolman concept to the measurement of a ligand size, as a profile over a radial distance from the metal (apex), has been developed. The representation of the Tolman cone angl e as a function of distance from the metal is termed a cone angle radi al profile (CARP). CARPs for PH3, PMe3, PEt3 and PPh3 have been determ ined and are described. CARPs for molecules containing the constrained phosphite ligands P(OCH2)(3)CMe, as determined in actual structures ( Cambridge Structural Database), have also been evaluated and indicate the invariant shape of the ligand in the different metal environments. The influence of the choice of the H atom van der Waals radius in ste ric measurements is also discussed.