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Issue 8, 1988
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Electrochemical studies of nickel(II) and cobalt(II) complexes of tetra-azamacrocycles bearing a pyridine functional group and X-ray structures of [NiII(L3)Cl]ClO4 and [NiII(L3)][ClO4]2·H2O {L3=meso-2,3,7,11,12-pentamethyl-3,7,11,17-tetra-azabicyclo[11.3.1]heptadeca-1(17),13,15-triene}

Abstract

The new complexes [NiII(L3)Cl]ClO4(1), [CoII(L3)(CH3CN)][ClO4]2, and [NiII(L3)][ClO4]2·H2O (2){L3=meso-2,3,7,11,12-pentamethyl-3,7,11,17-tetra-azabicyclo[11.3.1]heptadeca-1 (17),13,15-triene} have been prepared. Their redox chemistry and electrocatalytic behaviour in the CO2 reduction process were studied in comparison with related cobalt(II)–and nickel(II)–tetra-azamacrocyclic systems. The complex cation in (1)[monoclinic, space group P21/n, a= 9.457(4), b= 17.614(3), c= 14.078(4)Å, β= 107.39(2)°, Z= 4, R= 0.065 for 2 812 observed Mo-Kα data] is isostructural with the distorted tetragonal pyramidal CoII analogue. The increased atomic number of the nickel centre is reflected in a significant shortening (by ca. 0.03 Å) of the metal–N bond distances. In (2)[monoclinic, space group P21/c, a= 10.248(1), b= 17.958(4), c= 13.538(3)Å, β= 90.48(2)°, Z= 4, R= 0.076 for 3 310 observed Mo-Kα data] the two independent ClO4 groups are bridged by the water molecule through hydrogen bonding, and one ClO4 group is unidentately bound to the ‘square-planar’ metal atom by a long Ni–O bond of 2.838(7)Å. The macrocyclic L3 ligand adopts different conformations in (1) and (2): the substituted methyl groups at N(2) and N(4) are oriented anti with respect to each other in (1), but bear a syn relationship in (2).

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Article information


J. Chem. Soc., Dalton Trans., 1988, 2153-2159
Article type
Paper

Electrochemical studies of nickel(II) and cobalt(II) complexes of tetra-azamacrocycles bearing a pyridine functional group and X-ray structures of [NiII(L3)Cl]ClO4 and [NiII(L3)][ClO4]2·H2O {L3=meso-2,3,7,11,12-pentamethyl-3,7,11,17-tetra-azabicyclo[11.3.1]heptadeca-1(17),13,15-triene}

C. Che, S. Mak, W. Lee, K. Fung and T. C. W. Mak, J. Chem. Soc., Dalton Trans., 1988, 2153
DOI: 10.1039/DT9880002153

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