Intramolecular mobility of η 3-allylpalladium chloride complexes of different phosphines studied by two dimensional NMR spectroscopy

Abstract

The diastereomerization of η 3-allylpalladium chloride complexes (I–III) of the phosphines 4,4-dimethyl- t-6-methyl- t-2, r-3-diphenyl-1,3-oxaphosphorinane ( 1), o-bromobenzylphenylmethylphosphine ( 2) 1-phosphabicyclo[3.2.1]octane ( 3) has been studied by two-dimensional 1H NMR spectroscopy. Two processes are distinguished: a faster process, η 3 ⇌ η 1-conversion combined with a preferred CC-rotation (α-mechanism), and a slower process, η 3 ⇌ η 1-conversion combined with CC-rotation and CPd-rotation (γ-mechanism). In complexes containing bulky phosphines both processes are retarded.