Dipole-moment measurements on metal chelate complexes. Part 1. Dipole-moment and dielectric-relaxation measurements on square-planar and octahedral metal complexes of seven mercapto-β-diketones

Abstract

Dipole moments have been determined for iron(III), cobalt(III), nickel(II), palladium(II), platinum(II) and copper(II) complexes of the mercapto-β-diketones RC(SH):CH·C(O)R′[R = Me or Ph, R′= Ph; R = Me, C₄H₃S (2-thienyl), Ph. p-MeC₆H₄, or p-BrC₆H₄, R′= CF₃] from both static-polarization and dielectric-relaxation measurements. The moments clearly indicate cis-square-planar configurations for the nickel, palladium, platinum, and copper complexes, but do not distinguish unequivocally between facial- and meridional-octahedral configurations for the iron and cobalt complexes. Group dipole moments for the R substituents, except 2-thienyl, in the square-planar complexes have been derived from the dipole-moment data. The effect of the CF₃ group is discussed in terms of its influence on the electron density in the chelate ring.