A binucleating ligand, xylylene-bridged biscyclam α,α′-bis(1,4,8,11-tetraazacyclotetradecan-6-yl)-p-xylene ((cyclam)2-p-xyl) was prepared from α,α′-dichloro-p-xylene, diethylmalonate and 1,4,8,11-tetraazaundecane in three steps. The second step, aminolytic condensation of the tetraamine was critical. The ligand yielded a dinickel(II) complex (Ni2(cyclam)2-p-xyl](ClO4)4 · 4H2O. X-ray crystal analysis of the complex disclosed opposite and almost perpendicular occupation of the macrocycles to the bridging benzene ring through equatorial connection at the 6-carbons. Crystal data: tetragonal space group P42, a = 15.251(2), c = 9.821(2) A ̊ V = 2284.3(6) A ̊3 Z = 2. It is anticipated that conformational change in solution due to free rotation around the methylene carbon at the junction puts the macrocycles into face-to-face location with NiNi distance of ∼ 7.7 Å.
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