Anion Effect on the Structural Conformation of Tetranuclear Cadmium(II) Complexes
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- 作者：Ruihu Wang ; Daqiang Yuan ; Feilong Jiang ; Lei Han ; Yaqiong Gong ; and Maochun Hong
- 刊名：Crystal Growth & Design
- 出版年：2006
- 出版时间：June 2006
- 年：2006
- 卷：6
- 期：6
- 页码：1351 - 1360
- 全文大小：341K
- 年卷期：v.6,no.6(June 2006)
- ISSN：1528-7505
文摘
Six tetranuclear cadmium(II) complexes, Na[Cd4(hmt)2(H2O)6(dpa)4(NO3)]·8H2O (1), Na[Cd4(hmt)2(CH3OH)2(H2O)4(dpa)4I]·8H2O (2), Na[Cd4(hmt)2(H2O)6(dpa)4Br]·8H2O (3), Na2[Cd4(hmt)2(H2O)6(dpa)4(SCN)2]·4H2O (4), {Na[Cd4(hmt)2(H2O)6(dpa)4Cl](H2O)4}n (5), and {[Cd4(hmt)3(H2O)5(dpa)4](H2O)10}n (6) (hmt = hexamethylenetetramine, H2dpa = diphenic acid), were synthesizedby reactions of H2dpa, hmt, and CdX2 (X = NO3-, I-, Br-, Cl-, SCN-, and OAc-). All the complexes contain a basic unit [Cd4(dpa)4], in which four dpa ligands in a chelating bis-bidentate coordination mode link two six-coordinate and two seven-coordinatecadmium(II) centers. The research result demonstrates that the nature of the counterions has an important effect on the assemblyprocess of neutral and anionic mixed ligands with metal ions. In 1-3, NO3-, I-, or Br- bridges the two seven-coordinate CdIIcenters of the unit to form a discrete tetranuclear molecule with a cis-conformation and hmt as a terminal ligand coordinated to eachof the two six-coordinate cadmium(II) centers. Two SCN- in 4 acting as terminal ligands generate a discrete trans-conformationaltetranuclear cluster anion. The hmt in 5 acting as a 
-ligand links cis-conformational tetranuclear units by Cd-N bonds to generatea one-dimensional chain structure, while the hmt in 6 acting as a -ligand links the tetranuclear units by Cd-N bonds to generatea two-dimensional layer structure composed of a planar-conformation [Cd4(dpa)4] unit. The fluorescent studies in the solid at roomtemperature show that the six complexes exhibit strong violet or blue emissions in the range 370-500 nm arising from the charge-transfer transition and that the bridging anions have a significant effect on their fluorescent properties.
-ligand links cis-conformational tetranuclear units by Cd-N bonds to generatea one-dimensional chain structure, while the hmt in 6 acting as a -ligand links the tetranuclear units by Cd-N bonds to generatea two-dimensional layer structure composed of a planar-conformation [Cd4(dpa)4] unit. The fluorescent studies in the solid at roomtemperature show that the six complexes exhibit strong violet or blue emissions in the range 370-500 nm arising from the charge-transfer transition and that the bridging anions have a significant effect on their fluorescent properties.