Ligands form dative covalent bonds to TM ions. Why would a lone pair on (for example) a water molecule be attracted to a negative ion? Surely repulsion would occur?
Cobalt and Copper form negative complexes when they go under ligand subsitution with chloride ions. [Co(Cl)4]2- and [Cu(Cl)4]2-
The OP is not asking about negative complexes, he is asking about ligands being attached to negative transition metal ions (which do not exist, because the TMs are metals)