A magneto-structural relationship showing linear dependence of antiferromagnetic exchange coupling constant (-J) on Ni-0-Ni bridge angle as well as the intramolecular Ni--Ni distance has been obtained with a series of phenoxy-bridged macrocyclic dinickel(ii) complexes with centrosymmetric structures.

Sulfur-Nitrogen-Bonded Metal Chelates. 18. 1,3-Dipolar Cycloadditions to Coordinated Azide in Nickel(II) Complexes of the Types [Ni(S N N)(N3)] and [(S'l<~N)Ni(N3)Ni(POrS)](C104)

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A whole range of Robson-type tetraiminodiphenol macrocyclic ligands have been prepared as their perchlorate salts [H4L](ClO4)2 in high yield (ca. 90%) by a single-step [2 + 2] condensation reaction between 4-methyl(or tert-butyl)-2,6-diformyl(or diacyl)phenols and alpha,omega-diaminoalkanes (C2-C12) in the presence of acetic acid and NaClO4. The reduction of these 18- to 38-membered macrocyclic salts with NaBH4 have afforded corresponding tetraaminodiphenol macrocycles H2L'. The X-ray crystal structures of two of the tetraiminodiphenol macrocycles with the C2 and C4 lateral chains have been determined, and the optimized configurations for all of the macrocycles have been obtained by molecular mechanics calculations. The macrocycles have been characterized by elemental analysis and by IR, absorption, emission, and NMR spectroscopic study. The protonated tetraiminodiphenol macrocycles exhibit strong fluoroscence in methanol, acetonitrile, and nitromethane and undergo quenching when treated with triethylamine. The neutral macrocycles H2L, isolated by treating [H4L](ClO4)2 with excess of triethylamine, lack luminescence, as do the reduced tetraaminodiphenol macrocycles H2L'. The hydrolytic cleavage of [H4L](ClO4)2 has been studied.