The new isomeric pendent arm macrocyclic hexaamines trans- and cis- 6,13-diethyl-1,4,8,11-tetraazacyclotetradecane-6,13-diamine (L 5 and L 6 ) and their hexadentate coordinated cobalt(III) complexes are reported. X-ray crystal structural analyses of [H 4 L 5 ](ClO 4 ) 4 ·2H 2 O (triclinic, P 1̄, a = 7.840(1) Å, b = 13.6206(9) Å, c = 14.246(1) Å, α = 77.141(6)°, β = 86.539(9)°, γ = 86.465(9)°, Z = 2) and [CoL 5 ](ClO 4 ) 3 (monoclinic, C 2/ c, a = 14.461(6) Å, b = 11.580(2) Å, c = 15.865(5) Å, β 111.96(1)°, Z = 4) were performed. Cation disorder in the structure of [CoL 5 ](ClO 4 ) 3 is interpreted with the aid of molecular mechanics calculations, and solution conformational behavior is analyzed by NMR spectroscopy. It is found that the aqueous solution structure of [H 4 L 5 ] 4+ is unusually ordered, by comparison with other closely related ligand systems.
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Bernhardt et al. (1996) studied this question.