1,4,7,10-Tetraazacyclododecane-1,4,7-triacetic acid,10-[2-[[[4-[2-[[6-[2-[(2R)-2-amino-4-methyl-1-oxopentyl]hydrazinyl]-6-oxohexyl]amino]-2-oxoethyl]phenyl]methyl]amino]-2-oxoethyl]-