Patent ID: 8354512

Claim:
A metal complex, comprising: a paramagnetic metal ion; and a ligand of Formula (i) chelated with said paramagnetic metal ion: wherein, in Formula (i), X represents methylene, 1,1-cyclobutylene, 1,1-cyclopentylene, or 1,1-cyclohexylene; A 1 , A 2 and A 3 independently represent a hydrogen atom, a C 1 ˜C 3 alkyl group, a C 1 ˜C 3 phenylalkyl group, a C 1 ˜C 3 methoxyphenylalkyl group, diphenylmethyl or a C 1 ˜C 3 isothiocyanato phenylalkyl; A 4 represents a hydrogen atom, a nitro group, an amino group, a thiocyanato group, or —Z—Y, in which Z is a divalent linking group and Y is a biocompatible molecule, with the proviso that when X is methylene, A 4 cannot be a hydrogen atom or a nitro group; and R 1 , R 2 , R 3 , and R 4 independently represent a hydrogen atom, an amino group, a nitro group or a thiocyanato group.