Two-ring Flip Research Articles

Restricted rotation and preferred conformations in tris(pentafluorophenyl)phosphine platinum(II) complexes; the mechanism of helicity reversal in a co-ordinated triarylphosphine

Variable temperature 19F and 31P n.m.r. studies of some tris(pentafluorophenyl)phosphine platinum complexes show restricted rotation at low temperatures about the Pt–P and C(1)–P bonds with a preferred conformation in which none of the C(1)–P bonds lie in the platinum co-ordination plane; the mechanism of helicity reversal of the propeller-shaped ligand is a two-ring flip.

A theoretical study of the isomerization process in tris(2-thienyl)methyl radical

An INDO study has shown that the title compound exists in two diastereomeric propeller-like conformations, a cis form (C3 symmetry), and a trans form (C1 symmetry). The cis form is more stable than the trans form by 0·75 kcal/mole. The two forms undergo ready conformational interconversion by the two-ring flip mechanism, with activation energies of ca. 6 kcal/mole.

Stereochemistry of dimesityl-9-anthrylmethane and bis(2,6-xylyl)-1-(2-methylnaphthyl)methane. Evidence for the two-ring flip mechanism in triarylmethanes

Stereochemistry of dimesityl-9-anthrylmethane and bis(2,6-xylyl)-1-(2-methylnaphthyl)methane. Evidence for the two-ring flip mechanism in triarylmethanes