SYNTHESIS OF NOVEL MACROCYCLIC POLYAMINES WITH A PENDANT PHENOL GROUPAND PROPERTIES AND STRUCTURES OF THEIR COPPER(II) COMPLEXES

A series of new dioxocyclams with pendant phenol groups has been synth esized from coumarin 3-carboxylic ester and linear polyamines in reflu xing methanol/ethanol. Corresponding saturated cyclam derivatives were obtained by B-2 H-6 . THF reduction. Reaction of a dioxocylam derivat ive with Cu(ClO4)(2) in aqueous solution yields a singly deprotonated dioxotetraamine copper(II) complex, whose X-ray crystal structure has shown that the enolic tautomer of an amido group was coordinated to co pper(II). X-ray crystal data for [C17H25N4O3Cu]- ClO4 . H2O: monoclini c, space group P2(1)/a, a 15.554(3) Angstrom, b = 8.478(2) Angstrom, c = 17.250(3) Angstrom, beta = 111.4(1)degrees, V = 2117(1) Angstrom(3) , Z = 4, D-c = 1.614 mg/mm(3), F(000) = 1068, R = 0.040 and R(w) = 0.0 44. When coordinated to copper(II), the amido group deprotonates with pK(a) = 4.3. Potentiometric, electrochemical, and EPR spectral data of the complexes were studied. In the pH region 3-9, the substituent phe nol does not coordinate to the copper(II) ion; however, substituents d o have some effect on their Cu(II)/Cu(III) potential and complex stabi lity. In this study, we show that, besides doubly deprotonated copper( II) complexes, singly deprotonated dioxotetraamine complexes also exis t both in aqueous solution and in the solid state with considerable st ability. The existence of the singly deprotonated dioxotetraamine copp er(II) complex undoubtedly indicates that the complex deprotonates ste pwise and not simutaneous. This is a new conceptual discovery. The res ults provide us critical evidence for a discussion of the detailed mec hanism of complex formation and acid dissociation.