Stepwise reactions of two N_CH2CN or two N_CH2C(@NH)OMe groups attached to macrocyclic copper(II) complexes: Preparation of homo- and hetero-di-N-functionalized macrocyclic complexes

摘要

The hetero-functionalized macrocyclic complex [CuL2](ClO4)2 bearing one N_CH2C(@NH)OMe and one N_ CH2CN groups as well as [CuL3](ClO4)2 bearing two N_CH2C(@NH)OMe groups have been prepared selectively by the reaction of [CuL1](ClO4)2 (L2 = 2,13-bis(cyanomethyl)-5,16-dimethyl-2,6,13,17-tetraazatricyclo[ 16.4.0.1.1807.12]docosane) with methanol. The N_CH2C(@NH)OCH3 group in [CuL2](ClO4)2 is quite inert against acid hydrolysis. On the other hand, the functional pendant arms in [CuL3](ClO4)2 readily undergo acid hydrolysis. Both [CuL4](ClO4)2 bearing one N_CH2COOCH3 and one N_CH2C(@NH)OCH3 groups and [CuL5](ClO4)2 bearing two N_CH2OOCH3 groups have been prepared by the stepwise hydrolysis of [CuL3](ClO4)2. The reactivity of the functional pendant arms in [CuL1](ClO4)2 or [CuL3](ClO4)2 is quite different from that in [NiL1](ClO4)2 or [NiL3](ClO4)2. The crystal structure of [CuL2](ClO4)2 shows that the complex has a slightly distorted square-pyramidal coordination polyhedron with an apical Cu_N (N_CH2C(@NH)OCH3 group) bond. The N_CH2C(@NH)OCH3 and/or N_CH2COOCH3 groups in [CuL3](ClO4)2, [CuL4](ClO4)2, and [CuL5](ClO4)2 are involved in coordination, and the complexes have distorted trans-octahedral coordination polyhedron. The axial Cu_N (N_CH2C(@NH)OCH3 group) distance (2.396(7) _) of [CuL4](ClO4)2 is considerably longer than the Cu_N (N_CH2C(@NH)OCH3 group) distance (2.169(3) _) of [CuL2](ClO4)2.