MOLECULAR AND CRYSTAL-STRUCTURES OF 2 CHELATING-AGENTS FOR USE IN MRICONTRAST AGENTS

bamoyl)methyl]-1,4,7-triazaheptane-1,4,7-triacetic acid dihydrate, DTP A-BBA, C28H41N5O10, crystallizes in the monoclinic space group P2(1)/a , Z = 4 with unit cell dimensions a = 18.019(5), b = 7.204(1), c = 24. 288(7) angstrom, beta = 99.26(2)-degrees. R = 0.034 for 1916 unique re flections. bamoyl)methyl]-1,4,7-triazaheptane-1,4,7-triacetic acid dih ydrate, DTPA-BMA, C16H33N5O10, crystallizes in the monoclinic space gr oup P2(1)/c, Z = 4 with unit cell dimensions a = 17.472(4), b = 7.110( 2), c = 17.846(2) angstrom, beta = 96.02(1)-degrees. R = 0.043 for 451 3 unique reflections.There are two intramolecular hydrogen bonds in bo th molecules, which give them a folded conformation. The molecules cry stallize as zwitterions with the central of the three amine nitrogen a toms (N3) protonated. An extensive hydrogen-bonding network is found f or both structures, including a short unsymmetrical carboxyl-carboxyla te hydrogen bond, 2.522(3) angstrom (DTPA-BBA) and 2.504(2) angstrom ( DTPA-BMA), respectively, and an almost equally short carboxyl-water hy drogen bond, 2.570(4) angstrom (DTPA-BBA) and 2.575(2) angstrom (DTPA- BMA), respectively.