Template Syntheses and Crystal Structures of Nickel(II) Complexes of Hexaaza Macrocyclic Ligands with Pendant Functional Groups: Formation of a Coordination Polymer (original) (raw)

1994, Inorganic Chemistry

The nickel(II) complexes of hexaaza macrocyclic ligands 1-4, which incorporate functional groups such as-OH and-CN into the pendant arms attached at the uncoordinated bridgehead nitrogen atoms, are synthesized by the simple template condensation of ethylenediamine, formaldehyde, and primary amines with the appropriate functional groups. The hydroxyl pendant groups in the nickel(I1) complex of 1 react with acetic anhydride to produce the Ni(I1) complex of 5. The Ni(I1) complexes of 1-5 are in a square-planar geometry in solution. Their UVIvis spectra and electrochemical data are slightly affected by the type of functional group and the length of the pendant chain. The pendant hydroxyl groups in [Ni(1)I2+ and [Ni(2)12+ do not coordinate Ni(II) ion in water at pH 5 13.0 and an ionic strength 1.0 M (NaC104) or at pH 5 10.0 and an ionic strength 0.1 M (NaC104). The nickel(I1) complex with macrocycle 3 forms a coordination polymer on crystallization. [Ni(2)](C104)2 (NiC14H34N6C12010) crystallizes in the monoclinic space group P211c with a = 8.724(2) A, b = 14.581(2) A, c = 9.255(2) A, p = 103.84(1)", and Z = 2. The structure was solved by the direct method and refined to R values of R = 0.0335 and wR(F) = 0.0785 for 175 1 observed reflections (F > 4a(F)) measured with Mo Ka radiation on an Enraf-Nonius CAD-4 diffractometer. The Ni(I1) ion forms a square-planar geometq, coordinated by four secondary nitrogen donors of the macrocycle with the average Ni-N bond distance of 1.929(2) A. The oxygen atoms of the pendant hydroxyl groups form hydrogen bondings with the secondary NH's of the neighboring macrocyclic ligands. Coordination polymer [Ni(3)],(BF&,, (NiC1&8N&Fg) crystallizes in the monoclinic space group P21/n with a = 8.269(1) A, b = 8.559(1) A, c = 15.814(2) A, , 8 = 101.27(1)", and Z = 2. The structure was solved by the direct method and refined to R values of R = 0.0485 and wR(F) = 0.1395 for 1509 observed reflections (F > 6a(F)) measured with Mo Ka radiation on an Enraf-Nonius CAD-4 diffractometer. In the Ni(II) coordination polymer, each Ni(II) ion in the macrocyclic unit is coordinated by two nitrile groups of the neighboring macrocycles. The Ni(I1) atom is virtually in an octahedral geometry with the average Ni-N(macrocyc1e) bond distance of 2.056(3) 8, and the Ni(I1)-N(nitri1e) bond distance of 2.162(4) A.