X-Ray and nuclear magnetic resonance spectroscopic determination of the structure of chloro-[4-(chloro-t-butyl)methylene-2,5-di-t-butyl-1–3-η-cyclopent-2-enyl]triphenylphosphinepalladium and a novel example of stereochemically non-rigid behaviour in allylic complexes

Abstract

The structure of the t-butylacetylene trimer complex [Pd{Cl(Me₃CC₂H)₃}Cl]₂(I) has been elucidated from its ¹H and ¹³C n.m.r. spectra as well as by an X-ray structure determination of its triphenylphosphine adduct, [Pd{Cl(Me₃CC₂H)₃}Cl(PPh₃)]; complex (I) exists in two η³-allylic forms, an exocyclic and an endocyclic one, which interconvert.