Paramagnetic chelates

Abstract

Comounds having the formula ##STR1## wherein: a is 2 or 3; b is an integer from 0 to 4; Me.sup.(a+) is an ion of an element of atomic number from 57 to 70 or an ion of a transition metal of atomic number 21-29, 42 or 44; E.sup.(b+) is one or more physiologically biocompatible cation of an inorganic or an organic base or amino acid, said cation representing a total positive charge of b units; S is the group --A--O--R wherein: A is --(CH.sub.2).sub.m --; --CH.sub.2 --C(CH.sub.3).sub.2 --; m is an integer from 1 to 5; R is H; linear or branched alkyl of 1 to 8 carbon atoms, said carbon atoms being unsubstituted or substituted by one or more hyroxy group; aralkyl of 1 to 4 aliphatic carbon atoms; phenyl or phenyl substituted by halogen, amino, hydroxy or trifluoromethyl; (poly)-oxa-alkyl of 1 to 10 oxygen atoms and from 3 to 30 carbon atoms; R.sub.1 is R.sub.2 or --CH.sub.2 COOZ; --CH(CH.sub.3)COOZ; --(CH.sub.2).sub.n --N(CH.sub.2 COOZ).sub.2 ; hydroxy-arylalkyl radical in which the aryl radical is unsubstituted or substituted by hydroxy; R.sub.2 is --CH.sub.2 COOZ; --CH(CH.sub.3)COOZ; with the proviso that when R.sub.1 is --CH.sub.2 COOZ or --CH(CH.sub.3)COOZ, R.sub.2 is other than --CH.sub.2 COOZ and --CH(CH.sub.3)--COOZ ##STR2## wherein: R.sub.3 is --CH.sub.2 COOZ; --CH(CH.sub.3)COOZ; a monovalent radical having the structure S--CH--COOZ; X is a direct chemical bond; --O--; --S--; --NH--; --N--CH.sub.2 COOZ; --N--CH(CH.sub.3)COOZ; n is the integer 2 or 3, with the proviso that when X is a direct chemical bond, n is 1, 2 or 3; Z is H or a negative charge; with the proviso that, unless R represents a trifluoromethyl substituted phenyl or R.sub.1 is R.sub.2, Me.sup.(a+) is different from Fe.sup.(2+), Fe.sup.(3+), Gd.sup.(3+) and Mn.sup.(2+) and with the proviso that when R.sub.1 is R.sub.2 every molecule can contain not more than 500 nitrogen atoms.

Dependencies are inferred from the claim text.