Polymetallic Complexes. Part-XL VII. Complexes of Cobalt-, Nickel-, Copper-, Zinc-, Cadmium- and Mercury(II) with OON Tridentate and OON-NOO Bis-tridentate Chelating Azodye Ligands 4-Methyl-1.-(2'-hydroxy 3'-carboxy- 5' -sulphonicphenylazo-l')benzene and 1,3-Bis( 2'-hydroxy-3'-carboxy-5'-sulphonicphenylazo-l')benzene