The Mixed Complex of Tetracycline-Metal Chelates. II. Chlorotetracycline-Metal Chelates with Penicillin G.

Abstract

The existence of cationic complex of chlorotetracycline (CT)-metal chelate having 1 : 1 ratio of CT to metal suggested the possibility of formation of a mixed complex combined with other ligands. Preparation and properties of the mixed complexes with penicillin G (PenG) and PenG-metal complexes were studied using Th⁴⁺, Fe³⁺, Co²⁺, and Cu²⁺ ions in acid medium. Th (IV), Co (II), and Fe (III) complexes with PenG which have 1 : 1, 2 : 1, and 2 : 1 ratios of PenG to metal, respectively, were isolated by addition of water to a solution of PenG-K and metal salt in methanol. Copper (II) complex was not obtained. Methyl-PenG was used for the determination of the functional group of PenG. Methyl-Pent-Co (II) complex was also formed. Mixed complexes of CT-metal chelates with PenG were prepared from methanolic solution. Both CT-Th(IV)-PenG and CT-Fe(III)-PenG mixed complexes have a 1 : 1 : 1 ratio. Mixed complexes with Co (II) and Cu(II) did not show a definite composition. Desdimethylamino-chlorotetracycline-Th(Iv) chelate formed a mixed complex with PenG. This indicates the formation of mixed complexes through the metal. The mixed comp1exes were soluble in methanol and insoluble in water and ether. Color of the mixed complexes was similar to that of corresponding CT-metal chelates.