Cyclometallated compounds V. Double cyclopalladation of diphenyl pyrazines and related ligands

Abstract

2,3-Diphenylpyrazine and four structurally related ligands have each been singly and doubly cyclopalladated and the products characterised by 1H and 13C NMR studies of their acetylacetonate complexes. The structure of a doubly cyclometallated Pd(acac) complex of 2,3-diphenylpyrazine has been determined by an X-ray diffraction study (R = 0.039). A strong steric interaction between the two cyclopalladated phenyl rings is relieved by twisting; the two chelate ring mean-planes are mutually inclined at an angle of 19.6(5)°. © 1990.