Investigation of Molecular Interactions in the Carboxylato Zn(II) and Cd(II) Macrocyclic Complexes

Abstract

Coordination polymers on the basis of the assembly of metal ion "connectors" and multidentate ligand "linkers" have been of great interest due to their intriguing architectures and versatile applications.1-9 Metallotetraazamacrocycles bearing equatorial amines coordinated to the central metal ions and axial sites opened for incoming "linkers" are good "connectors" as building blocks for the construction of coordination polymers. 10-15Among multidentate ligands, polycarboxylates have been widely used as "linkers" due to their versatile coordination modes toward metal ions. [16][17][18][19] An fdc (fdc = 1,1'-ferrocenedicarboxylate ion) ligand as a kind of polycarboxylates has attracted attention not only in the field of coordination chemistry but also in the field of organometallic chemistry. [20][21][22][23] During our efforts to explore the molecular interactions between metallomacrocycles and polycarboxylate ligands in zinc(II) and cadmium(II) tetraazamacrocycles containing bridging polycarboxylate ligands, we successfully synthesized and structurally characterized two 1D zinc(II) coordination polymers 1 and 2, where each ferrocenyl of bridging fdc ligands adopts different conformation, and a macrocyclic cadmium(II) dimer 3. Thus, two Cp (Cp = cyclopentadienyl) rings of fdc ligands in 1 are mutually staggered, whereas they are eclipsed in 2. The cadmium(II) cyclams with folded macrocycles are bridged by an oxalate ligand in 3. In this report we describe the details of the synthesis and structures of 1-3.

Axial Interactions of Nitrate Ions to a Silver(II) Ion Supported by C-H…O Hydrogen Bonds in a Silver(II) Tetraazamacrocyclic Complex

“…4 The resulting differences between the metal complexes formed with macrocycles L1 and L2 in the above examples have been just ascribed to the structural characteristics of the macrocycles L1 and L2. However, it has not been clearly understood what the factors influence to the chemical and structural properties of metal complexes, and explanation and discussions are insufficient to explain the differences between the metal complexes formed with macrocycles L1 and L2.…”

“…[1][2][3][4][5][6] Although the macrocycles L1 and L2 show similar coordination tendencies to metal ions and form corresponding metal complexes, the chemical and structural properties of metal complexes are greatly influenced by the stereochemistry of cyclohexane rings fused on the 14-membered tetraazamacrocycle. Thus, the axial coordination of solvent molecules to the…”

Structure and Properties of Macrocyclic Nickel(II) Coordination Polymer Bearing 1,1'-Ferrocenedicarboxylate Bridging Ligand

“…[8][9][10] Although the fdc ligand has two carboxylate groups on the rigid cyclopentadienyl (Cp) rings, it is fairly flexible in binding to metal ions due to the possible rotation of Cp rings about the Cp-Fe-Cp axis.…”

“…In our early work, we reported the effects of macrocycles to the torsional angles of Cp rings in macrocyclic zinc(II) complexes bearing ferrocenyl moieties, where the complexes with eclipsed and staggered structures between the Cp rings were isolated in the solid state, respectively. 8 Moreover, recent advances of functionalized ferrocenes as potential chemotherapeutic drugs urge researchers to secure more examples of complexes containing ferrocenyl moieties.…”

“…4,8,12,13 Therefore, flexible ligands as building blocks in coordination polymers have been used widely to date. In our early work, we reported the effects of macrocycles to the torsional angles of Cp rings in macrocyclic zinc(II) complexes bearing ferrocenyl moieties, where the complexes with eclipsed and staggered structures between the Cp rings were isolated in the solid state, respectively.…”