Provided is a novel rare earth complex which exhibits compatibility with a polymer or the like, and which has a glass transition temperature. Also provided are: a ligand for forming the rare earth complex; a rare-earth-complex production method; and a use of the rare earth complex. This ligand is a compound represented by general formula (1), namely X1-L1-Ar-L2-X2 (in general formula (1): Ar represents an aromatic heterohydrocarbon group or an aromatic hydrocarbon group; L1 and L2, which are bonded to Ar, are bonded so as form an angle with Ar at the center within the molecule; L1 and L2 independently represent linkers; and X1 and X2 independently represent a phosphoryl group represented by O=P(Ar11Ar12)- (with the caveat that Ar11 and Ar12 independently represent a substituted or unsubstituted aryl group, a substituted or unsubstituted heteroaryl group, or a substituted or unsubstituted aralkyl group)). Provided is a complex provided with a cluster structure including the aforementioned compound and a rare earth element.
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