TEMPLATE CONDENSATION-REACTIONS OF FORMALDEHYDE WITH TETRAAMINES AND ETHYLENEDIAMINE - PREPARATION, PROPERTIES, AND STRUCTURES OF NICKEL(II) AND COPPER(II) COMPLEXES OF HEXAAZA MACROTRICYCLIC LIGANDS 1,3,6,8,11,14-HEXAAZATRICYCLO[12.2.1.18,11]OCTADECANE AND 1,3,6,8,12,15-HEXAAZATRICYCLO[13.3.1.18,12]EICOSANE

Square-planar Ni(II) and Cu(II) complexes of macrotricyclic ligands 1,3,6,8,11,14-hexaazatricyclo[12.2.1.1 8,11]octadecane (A) and 1,3,6,8,12,15-hexaazatricyclo[13.3.1.1 8,12]eicosane (B) have been prepared from the simple template condensation reactions of formaldehyde and ethylenediamine with 2,2,2-tet and 3,2,3-tet, respectively, in the presence of metal ion. Infrared and UV/vis spectra indicate that complexes [M(B)2+ containing 1,3-diazacyclohexane small-ring moieties fused to the hexaaza macrocyclic framework exert weaker M-N interactions and weaker ligand field strengths than complexes [M(A)]2+ containing 1,3-diazacyclopentane ring moieties fused to the macrocycle. ]Ni(A)[(Clo4)2 (A = C12H26N6) crystallizes in the monoclinic space group P2(1)/c with a = 15.502 (7) angstrom, b = 9.476 (9) angstrom, c = 13.491 (5) angstrom, beta = 93.14 (4) degrees, and Z = 4. The structure was solved by direct methods and and refined anisotropically to R values of R = 0.055 and R(w) = 0.057 for 2692 observed reflections with F greater-than-or-equal-to 2-sigma(F) measured with Mo K-alpha radiation on a CAD-4 diffractometer. [Ni(B)](ClO4)2. 1/2 H2O (B = C14H30N6) crystallizes in the monoclinic space group C2/c with a = 32.569 (15) angstrom, b = 9.577 (4) angstrom, c = 14.400 (6) angstrom, beta = 111.31 (4) degrees, and Z = 8. The structure was solved by Patterson methods and refined to R values of R = 0.038 and R(w) = 0.048 for 3334 observed reflections measured with Mo K-alpha radiation on a CAD-4 diffractometer. The X-ray structures indicate that two 1,3-diazacyclopentane ring moieties in [Ni(A)](ClO4)2 and two 1,3-diazacyclohexane ring moieties in [Ni(B)](ClO4)2. 1/2 H2O are located oppositely and almost perpendicularly to the plane of the ruffled 14-membered macrocycle. The average Ni-N bond distances are 1.923 (8) angstrom for [Ni(A)](ClO4)2 and 1.951 (13) angstrom for [Ni(B)](ClO4)2.1/2H2O. The fusion of the 1,3-diazacyclopentane ring forces more acute angles within the six-membered chelate, accounting for the slight contraction. The Ni(II) complexes of A and B exhibit equilibria between square-planar and octahedral species in aqueous solutions. The equilibrium constant for square-planar/octahedral conversion is much larger for [Ni(B)]2+ than for [Ni(A)]2+. Cyclic voltammetry indicates that both oxidation and reduction of Ni(II)/Ni(III) and NI(II)/Ni(I) are significantly easier for [Ni(B)]2+ than for [Ni(A)]2+.