Reactions of N-cyanomethyl groups attached to a tetraaza macrocyclic copper(II) complex leading to the formation of various hetero-functionalized macrocyclic complexes

New hetero-functionalized macrocyclic complexes CuL²](ClO₄)₂ (I) and CuL³](ClO₄)₂ (II) bearing one N-CH₂CONH₂ or one N-CH₂C(NH)NH(CH₂)₂CH₃ pendant arm as well as one N-CH₂CN group have been prepared by the selective reaction of water or n-propylamine with one of the two N-CH₂CN groups in CuL¹](ClO₄)₂ (L¹ = 2,13-bis(cyanomethyl)-5,16-dimethyl-2,6,13,17-tetraazatricyclo16.4.0.^1.180^7.12]docosane). The complex CuL⁴](ClO₄)₂ (III) bearing both N-CH₂CONH₂ and N-CH₂C(NH)NH(CH₂)₂CH₃ pendant arms can be prepared by either the reaction of I with n-propylamine or the hydrolysis of II. The N-CH₂CONH₂ and/or N-CH₂C(NH)NH(CH₂)₂CH₃ groups of I, II, and III are coordinated to the metal ion. The crystal structure of II shows that the complex has distorted square-pyramidal coordination polyhedron with a considerably strong apical Cu-N (N-CH₂C(NH)NH(CH₂)₂CH₃) bond (2.101(6) Å). The addition of HClO₄ (?0.01 M) to an acetonitrile (or DMSO) solution of II or III produces Cu(HL³)](ClO₄)₃ (IIa) or Cu(HL⁴)](ClO₄)₃ (IIIa), showing that the N-CH₂C(NH)NH(CH₂)₂CH₃ pendant arm of each complex is readily protonated in the non-aqueous solvent; the resulting N-CH₂C()NH(CH₂)₂CH₃ group of IIa or IIIa is not involved in coordination. However, the N-CH₂C(NH)NH(CH₂)₂CH₃ group of II is not protonated even in ?1.0 M HClO₄ aqueous solution. In the case of III, most of the complex exists as the protonated form Cu(HL⁴)]³⁺ in ?0.1 M HClO₄ aqueous solutions.