JEE Main · 2019 · 09 Apr 2019 · Shift 2 · Coordination Compounds

The ligand drawn is a polydentate chelating ligand carrying several nitrogen and oxygen donor atoms. A common transition-metal ion, being smaller and usually of coordination number six, can take in only six of those donors, so the ligand binds as hexadentate there. A larger inner-transition ion, a lanthanide or actinide, accepts a higher coordination number and can engage up to eight of the donor atoms, so its maximum denticity rises to eight. The two figures are therefore six toward the transition-metal ion and eight toward the inner-transition ion.