The two palladium(II) complexes, [PdL22222][ClO4]2·H2O 1 and [Pd(H−2L22222)]·H2O 2 with 1,11-bis(2-pyridylmethyl)-1,4,8,11-tetraazacyclotetradecane-5,7-dione, L22222, were prepared and characterized by X-ray crystallography and UV-visible spectroscopy. In 1 the palladium centre is co-ordinated by the tertiary amines of the macrocycle and the two pyridylmethyl nitrogens, forming a square-planar geometry in which two amide nitrogen groups remain protonated and do not take part in co-ordination. Moreover, there is a weak interaction between palladium and H(–N(8)) [d(PdII ⋯ H) = 2.90 Å]. In contrast, 2 isolated under basic conditions has a square-planar geometry but the palladium ion is co-ordinated by two deprotonated amides and the two tertiary amines of the macrocycle. In solution the reversible interconversion between complexes 1 and 2 easily occurs through pH-dependent deprotonation of the amide group.
两种
钯 (II) 配合物,[Pd
L22222][ClO4]2·
H2O 1 和 [Pd(H−2
L22222)]· 2 与 1,11-双(2-
吡啶基甲基)-1,4,8,11-制备了四
氮杂环十四烷-5,7-二酮
L22222,并通过 X 射线晶体学和紫外-可见光谱对其进行了表征。在1中,
钯中心由大环的叔胺和两个
吡啶基甲基氮配位,形成方形平面几何形状,其中两个酰胺氮基团保持质子化并且不参与配位。此外,
钯和 H(–N(8)) [d(PdII ⋯ H) = 2.90 Å] 之间存在弱相互作用。相反,在碱性条件下分离的2具有方形平面几何形状,但
钯离子由两个去质子化酰胺和大环的两个叔胺配位。在溶液中,配合物 1 和 2 之间的可逆相互转化很容易通过酰胺基团的 pH 依赖性去质子化发生。