Do ligands with a positive charge exist?
Aromatic cations like the tropylium cation ($\ce{C7H7+}$)[1] or the cyclopropenyl cation ($\ce{C3H3+}$)[2] can coordinate to metals, creating sandwich or half-sandwich compounds. The positive charge is shared by all carbon atoms of the rings.




Anderson, J. E.; Maher, E. T.; Kool, L. B. Electrochemical and spectroelectrochemical properties of the titanium sandwich complexes (Cp)Ti(L) and (Cp*)Ti(L), where L is either cyclooctatetraene (C8H8) or the tropylium ion (C7H7+). Organometallics 1991, 10 (5), 1248–1254. DOI: 10.1021/om00051a009.
Lichtenberger, D. L.; Hoppe, M. L.; Subramanian, L.; Kober, E. M.; Hughes, R. P.; Hubbard, J. L.; Tucker, D. S. Electron distribution and bonding in η3-cyclopropenyl-metal complexes. Organometallics 1993, 12 (6), 2025–2031. DOI: 10.1021/om00030a011.