X-ray structure and properties of a dinuclear palladium(II) complex [Pd2(μ-L)4] with four adenine-based bridges in a paddle wheel-like arrangement

Abstract

A unique dinuclear palladium(II) complex of the general composition [Pd 2 (μ-L) 4 ]· x DMF (DMF = N,N′-dimethylformamide, x = 2 for 1a , x = 4 for 1b ) was prepared by a reaction of K 2 [Pd(mal) 2 ] and two molar equivalents of 2-chloro-N6-benzyl-9-isopropyladenine (HL); mal stands for the malonate dianion. The prepared complex was fully characterized by elemental analysis, molar conductivity measurements, IR, Raman and NMR spectroscopies, ESI + mass spectrometry, TG/DTA thermal studies (for 1a ), and by a single crystal X-ray analysis (for 1b ). The results revealed that both metal centres are bridged by four N6-deprotonated 2-chloro-N6-benzyl-9-isopropyladenine molecules (L) in a paddle wheel-like arrangement with the Pd1⋯Pd1A separation of 2.7532(4) Å. Each of the L molecules is coordinated to the Pd(II) ions through its N6 and N7 atoms. The geometry around each of the central atoms can be described as distorted square-planar formed by two N6 and two N7 atoms. The [Pd 2 (μ-L) 4 ]· x DMF complex represents the first dinuclear transition metal complex with two central ions bridged by four adenine derivatives coordinated through their N6 and N7 atoms. The [Pd 2 ( μ -L)4]· x DMF complex (L=a deprotonated form of 2-chloro-N6-benzyl-9-isopropyladenine) represents the first dinuclear transition metal complex with two central Pd(II) atoms [Pd1···Pd1A separation of 2.7532(4)] connected by four adenine-based ligands in a paddle wheel-like arrangement coordinated through their N6 and N7 atoms.