Dipole moment measurements on metal complexes of monothio-β-diketones

Dipole moments have been reported for over 200 monothio-β-diketone complexes, Met(RCSCHCOR′), (n  2, 3). The data show that the nickel(II), palladium(II), platinum(II), and copper(II) complexes are cis-square-planar, the zinc(II) complexes are tetrahedral, and the chromium(III), iron(III), ruthenium(III), cobalt(III), and rhodium(III) complexes are facial (cis)-octahedral. Measurements of the dipole moments of a considerable number of the metal complexes by both the static polarization and dielectric relaxation methods have shown that atomic polarization is ca. 0.3 D in square-planar, 0.5 D in tetrahedral, and 0.9 D in octahedral complexes.A large number of complexes, Met(RCSCHCOR?_n (R  phenyl or X-substituted phenyl, R′ CF₃) have been studied. The difference in the values of the dipole moments depend upon: (a) the magnitude and vector direction of the PhX bond moments; (b) the inductive effect arising from the difference in electron density of the C¹ and C⁵ carbon atoms of the ligand moiety — this is affected by the nature and position of the substituent X on the phenyl ring; (c) the change in moment brought about by the mesomeric effect of the substituent X.