[Pd(tmeda)(Hampy-N1)(H2O)]2+ (tmeda = N,N,N′,N′-tetramethylethylenediamine; Hampy = 2-aminopyridine) forms in the presence of Ag+ at pH 8–9 a triangular Pd2Ag complex containing two deprotonated ampy− ligands. It has been crystallized and structurally characterized with nitrate anions and a second co-crystallized AgNO3, [Pd(ampy)(tmeda)}2Ag(µ-NO3)2Ag(NO3)2] (5). The two amidopyridine ligands are triply bridging, binding to Ag+ in a monodentate fashion viaN1, and to two PdII centres in a µ2-bridging fashion via the monodeprotonated N2 position. The resulting four-membered Pd(ampy)2Pd metallacycle is syn-planar with Pd⋯Pd separations of 3.0878(13) Å. The Pd⋯Ag distances are 3.0879(14) Å in 5 (isosceles triangle). In solution (D2O), the two ampy− ligand in 5 are non-equivalent as concluded from a detailed 1H NMR spectroscopic study and confirmed by a 13C NMR spectrum. Removal of Ag+ from 5, as achieved by addition of Cl−, causes cluster degradation and linkage isomerization of PdII(tmeda) from the exocyclic N2 to the endocyclic N1 position.
在pH 8-9的条件下,存在Ag+时,形成[Pd(tmeda)(Hampy-N1)(
H2O)]2+(tmeda = N,N,N′,N′-
四甲基乙二胺;Hampy = 2-
氨基吡啶),这是一个包含两个去质子化ampy−
配体的三角形Pd2Ag复合物。它已经与
硝酸根阴离子和第二个共结晶的Ag 共同结晶,并进行了结构表征,得到的化合物为[ Pd(ampy)(tmeda)}2Ag(μ-
NO3)2Ag( )2] (5)。两个酰胺
吡啶配体以三重桥联的方式,通过N1以单齿
配体的方式与Ag+结合,并通过去质子化的N2位置以μ2-桥联的方式与两个PdII中心结合。最终形成的四元Pd(ampy)2Pd
金属环呈syn-planar构型,Pd⋯Pd间距为3.0878(13) Å。化合物5中Pd⋯Ag距离为3.0879(14) Å(等腰三角形)。在溶液(D2O)中,化合物5中的两个ampy−
配体由于详细的1H NMR光谱研究得出的结论是非等效的,并通过13C NMR谱进一步确认。从5中去除Ag+(通过添加Cl−实现)会导致簇降解和PdII(tmeda)链接异构化,从外环的N2转变到内环的N1位置。