Introduction:
In coordination complexes, ligands donate electrons to the central metal atom. However, despite receiving electrons, the metal still carries a positive charge. This can be explained by the concept of electronegativity and the strength of the metal-ligand bond.

Ligand Donation:
Ligands are electron-rich species that can donate their lone pair of electrons to the central metal atom. This donation results in the formation of a coordinate covalent bond between the metal and ligand. The metal atom now has a full valence shell and is said to be in a more stable state.

Electronegativity:
Electronegativity is the ability of an atom to attract electrons towards itself. In a metal-ligand complex, the metal atom is usually less electronegative than the ligand. Therefore, when the ligand donates its electrons to the metal, the metal atom still retains a positive charge.

Metal-Ligand Bond Strength:
The strength of the metal-ligand bond also plays a role in determining the charge on the metal atom. A stronger bond between the metal and ligand results in a greater transfer of electron density from the ligand to the metal. As a result, the metal atom will have a greater positive charge.

Conclusion:
In conclusion, the positive charge on a metal atom in a coordination complex is due to its lower electronegativity compared to the ligand and the strength of the metal-ligand bond. Despite receiving electrons from the ligand, the metal still carries a positive charge.