Tackling Metal-Metal Bond in the Framework of the Bond Valence Sum Formalism. The Case of Cupric Acetate

摘要

It is demonstrated that Eq. (i) can tackle metal-metal bond. This is exemplified by its application to some thirteen Cu(trichloroacetate)2L (L is a monodentate ligand) complexes and Cu(acetate)_2H_2O. This cannot be done by Pauling's method which is used currently to calculate the bond valence sum (BVS) of a metal in a complex. In Eq. (i),V_i is the BVS of the metal i whose coordination number is n, r_(ij) the bond distance between the metal i and its jth neighbour and R the bond valence parameter characteristic of the bond between the atoms i and j. Bond valence is essentially oxidation state per bond. It is shown that the contribution v(Cu-Cu) of the Cu~(2+)-Cu~(2+) bond towards the total BVS of a copper atom increases as the metal-metal distance decreases. An excellent linear correlation is obtained between v(Cu-Cu) and -2J (the exchange coupling constant).