NEUTRAL GADOLINIUM(III) COMPLEXES OF BULKY OCTADENTATE DTPA DERIVATIVES AS POTENTIAL CONTRAST AGENTS FOR MAGNETIC-RESONANCE-IMAGING

A series of bulky and neutral gadolinium complexes of [bis(R-amide)dtp aH(3)] (where R = Pr-i, Bu(i), Bz and phenylethyl, L(1)-L(4)) with pot ential application as contrast agents for magnetic resonance imaging h as been prepared and characterized; the relaxivity of these complexes is comparable to the contrast agent [Gd(dtpa)(H2O)](2-) which is curre ntly used in clinics; the X-ray structure analysis of the gadolinium(I II) complex of L(3) reveals a neutral nine-coordinate complex featurin g a water molecule in the tricapped trigonal prismatic metal coordinat ion sphere.