Studies of some co-ordination compounds of platinum, palladium, and nickel

Abstract

The four covalent complexes of nickel (II) fall into two classes (a) the paramagnetic group containing two unpaired electrons and (b) those which are diamagnetic. Whenever X-ray strucural data or electric dipole moments are available the latter have been shown to be square planar. The diamagnetism indicates that one dγ orbital is not used by non-bonding electrons and this orbital together with a 4s and two 4p orbitals gives rise to the Pauling picture of four square planar 3d4s4p2 bonds. Bivalent Platinum and Palladium form square complexes with great facility; in fact, no paramagnetic complexes of Pt (II) or Pd(II) are known. X-ray analysis has shown the following amine complexes to have the co-planar configuration.