How many bonds could each of the following chelating ligands form with a metal ion?
a) acetylacetone; a common ligand in organometallic catalysts
b) diethylenetriamine; used in a variety of industrial processes
c) salen; a common ligand for chiral organometallic catalysts
d) porphine; often used in supermolecular chemistry as well as catalysis; biologically, porphine is the basis for many different types of porphyrin-containing proteins, including heme proteins:
