3-[10,15-Bis(2-{(3S,4S,2R,5R,6R)-6-[(carboranylcarbonyloxyoxy)methyl]-3,4,5-tris(carboranylcarbonyloxyoxy)(2H-3,4,5,6-tetrahydropyran-2-yloxy)}-1-(carboranylcarbonyloxy)ethyl)-20-(2-carboxyethyl)-5,9,14,19-tetramethyl-21,22,23,24-tetraazapentacyclo[16.2.1.1<3,6