The structural chemistry of Pd and Pt

As long ago as 1893 Werner suggested that the four atoms or groups attached to divalent Pd or Pt atoms in certain molecules were coplanar with the metal atom, this suggestion being made to account for the existence of compounds such as Pt(NH3)2Cl2 in two isomeric forms. For coplanar bonds there would be cis and 

Dipole moment measurements make possible a distinction between cis and trans planar molecules or ions, the cis isomer having a larger dipole moment and the trans a smaller or zero moment, depending on the nature of the ligands, for example  

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