title: Cadmium(II) and copper(II) complexes with imidazole-containing tripodal polyamine ligands: pH and anion effects on carbon dioxide fixation and assembling.
abstract: A new Cd(II) complex [Cd3(L)3(mu3-CO3)](ClO4)4.2CH3CN (1) with two-dimensional (2D) network structure was obtained by reaction of an imidazole-containing tripodal polyamine ligand N1-(2-aminoethyl)-N1-(2-imidazolethyl)-ethane-1,2-diamine (L) with Cd(ClO4)2.6H2O at pH 9.0 in air. The carbonate anions (CO3(2-)) are from the hydration of the atmospheric carbon dioxide, which is the same as in the previously reported Cu(II) complex [Cu3(L)3(mu3-CO3)](ClO4)4.3CH3CN (2). However, the coordination mode of CO3(2-) in 1 is mu3-eta2:eta2:eta2 while the one in 2 is mu3-eta1:eta1:eta1. One-dimensional (1D) chain Cd(II) and Cu(II) complexes [Cd(L)Cl]ClO4.H2O (3) and [Cu(L)(H2O)](ClO4)2 (4) without CO3(2-) were prepared by a similar method as that for 1 and 2 except for the different reaction pH, namely, 3 and 4 were obtained at pH 7 while 1 and 2 were obtained at pH 9. In addition, when Cu(NO3)2 was used to react with L at pH 9, a unique 1D double-stranded helical chain complex [Cu(L)Cl]NO3.1.25H2O (5) was obtained. The results revealed that the reaction pH and the counteranion have great impact on the carbon dioxide absorption and hydration as well as on the assembling and structure of the complexes. The magnetic property of complex 2 was investigated in the temperature range of 1.8-300 K, and weak ferromagnetic coupling among the mu3-eta1:eta1:eta1-CO3(2-) bridged Cu(II) atoms was observed.
authors.affiliation: Coordination Chemistry Institute, State Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, People's Republic of China.
authors.forename: Ling-Yan
authors.initials: LY
authors.lastname: Kong
authors.forename: Hui-Fang
authors.initials: HF
authors.lastname: Zhu
authors.forename: Yong-Qing
authors.initials: YQ
authors.lastname: Huang
authors.forename: Taka-aki
authors.initials: TA
authors.lastname: Okamura
authors.forename: Xi-Hong
authors.initials: XH
authors.lastname: Lu
authors.forename: You
authors.initials: Y
authors.lastname: Song
authors.forename: Guang-Xiang
authors.initials: GX
authors.lastname: Liu
authors.forename: Wei-Yin
authors.initials: WY
authors.lastname: Sun
authors.forename: Norikazu
authors.initials: N
authors.lastname: Ueyama