Syntheses, crystal structures and characterizations of tetraazamacrocyclic complexes meso-[Ni(1,7-CT)]I₂ and dl-[Ni(1,7-CT)][Fe(CN)₅NO] · H₂O

Abstract

A centrosymmetric meso tetraazamacrocyclic nickel(II) complex meso-[Ni(1,7-CT)]I₂ (1) and a novel racemic ion-pair double complex dl-[Ni(1,7-CT)][Fe(CN)₅NO] · H₂O (2) (1,7-CT = 5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradeca-1,7-diene) have been synthesized and characterized by elemental analyses, single crystal X-ray diffraction, ¹H NMR, IR, UV-vis spectra and TG-DTA analyses. Results reveal that the structure of 1 consists of the overlapping meso-[Ni(1,7-CT)]²⁺ cation with the perfect square-planar NiN₄ chromophore and outer iodides. Compound 2 contains four kinds of structurally distinct ion-pairs a, a′, b and b′ that are made up of distorted square dl-[Ni(1,7-CT)]²⁺ cations and distorted octahedral [Fe(CN)₅NO]²⁻ anions, which are divided into two groups with an enantiotropic relationship between them in each group. They are linked by van der Waals forces and hydrogen bonds involving H₂O and arranged alternatively in adjacent layers, forming an orderly three-dimensional network structure.

Keywords:

• Tetraazamacrocyclic nickel(II) complex
• Nitroprusside
• Ion pairs
• Crystal structures
• Characterizations