Patent ID: 6897218

Claim:
A metal complex of a piperazineNONOate derivative of formula: where a) R 1 and R 2 independently represent: hydrogen, linear or branched (C 1 -C 4 ) alkyl, optionally substituted by 1 or 2 groups selected from the group consisting of hydroxy, (C 1 -C 4 ) alkoxy, (C 1 -C 4 ) alkylthio, amino, (C 1 -C 4 ) alkylamino, di-(C 1 -C 4 ) alkylamino, carboxy, carbo(C 1 -C 4 ) alkoxy, aryl, aryloxy, arylthio; or b) R 1 and R 2 taken together, represent one of the following groups: ═CR 3 -aryl, where R 3 represents hydrogen, (C 1 -C 4 ) linear or branched chain alkyl, optionally substituted by 1 or 2 groups selected from the group consisting of hydroxy, carboxy, aryl; n represents a whole number ranging from 2 to 4; M + represents a cation of a transition metal or zinc; x represents a whole number which varies from 1 to 3, and indicates the charge units of the cation of the transition metal or of the zinc in relation to its stable oxidation state; A 31 represents an inorganic or organic anion which forms stable salts with the NONOate metal complex; y represents a whole number which varies from 1 to 3, and indicates the charge of the anion; m represents a whole number including zero, or a fractional value, indicating the number of anions required to balance the cationic charge of the NONOate metal complex and is related to the values of x, y, k and w by the relationship: m = ( x + k ) - ( 1 + w ) y where w is the number of possible further anionic charge units and k is the number of possible further cationic charge units present in the NONOate ligand substrate.