Multnuclear complex and polymer thereof

To provide a multinuclear complex including at least one ligand L satisfying the following requirements (i), (ii) and (iii), and a plurality of metal atoms in a molecule: (i) having a group having polymerizable reactive multiple bonds, and/or a ring-opening polymerizable ring, (ii) having five or more coordination atoms bonding to the metal atoms, and (iii) being soluble in a solvent.