Metal organo phosphorous compounds for NMR analysis

A method for NMR analysis comprising administering to a host an NMR signal affecting amount of a complex of

• (a) a metal ion selected from a member of the group consisting of metal ions having atomic number 21 to 29 inclusive, 42 to 44 inclusive and the lanthanides having atomic numbers 57 to 70 inclusive, and
• (b) an organophosphorous metal ion chelating ligand comprising a phosphonylorgano phosphinate to form complexes of the formula:
• ##STR7## wherein n=2 to about 100;
• n.sub.1 =the number of negative charges in n ##STR8## groups;
• a=1, 2, or 3;
• M=a metal ion described hereinabove;
• v=the valence of M;
• R.sub.1 =O.sup.- or an organophosphenate comprising ##STR9## R=alkyl moiety, whether branched chain or straight chain, cyclic hydrocarbon moiety having from 3 to about 10 carbon atoms, said cyclic hydrocarbon moiety being saturated or unsaturated and including fused ring cyclic hydrocarbon moieties;
• heterocyclic hydrocarbon moieties having from 1 to 2 hetercyclic nitrogen, phosphorous, sulfur or oxygen atoms in said heterocyclic ring, said heterocyclic hydrocarbon moiety being saturated or unsaturated,
• and subjecting said host to NMR analysis.