Cyano-bridged heterometallic complexes directed by binuclear copper units

Abstract

A tridentate N,O-donor, 1,3-bis(3,5-dimethylpyrazol-1-yl)propan-2-ol (HL), has been employed to synthesize cyano-bridged complexes and six heterometallic complexes with [Cu₂L₂] or [Cu₂L₂(H₂O)] have been generated by using slow diffusion. With slightly different synthetic conditions, subtle variations in the crystal structures of the complexes occur. [Cu₂L₂][Fe(CN)₅NO]⋅2CH₃CN (1) and [Cu₂L₂][Fe(CN)₅NO]⋅H₂O (2), synthesized in different solvents with the same precursor, exhibit a very similar 1-D zig-zag chain motif in different space groups, P2₁ and P-1, respectively. Similarly, [Cu₂L₂(H₂O)][Ni(CN)₄]·H₂O (3) and [Cu₂L₂][Ni(CN)₄]⋅H₂O (4), synthesized with different diffusion methods, feature trinuclear and 1-D zig-zag chain structures, which indicates a solvent effect of water. [Cu₂L₂(H₂O)]₂[Cu₂L₂][W(CN)₈]₂·8H₂O (5) is composed of two [W(CN)₈]³⁻ and three [Cu₂L₂]²⁺ units. In the octanuclear structure, [W(CN)₈]³⁻ and one [Cu₂L₂]²⁺ bridge and the other two [Cu₂L₂]²⁺ are terminal to stop extending the 1-D structure. [CuL][Ag_2.24Cu_0.76(CN)₄] (6) exhibits a discrete structure, in which the complex anion forms a unique 2-D 6³ network and the complex cations are inserted in the space between two adjacent networks. Magnetic properties of 1 and 4 are discussed.

Keywords:

• Cyano-bridged complexes
• Heterometallic complexes
• Crystal structures
• Solvent effect

Acknowledgements

This study was supported by the National Natural Science Foundation of China (Grant 90922032, 21101113), MOST (Grant 2007CB815305) of China, and the NSF of Tianjin (Grant 09JCZDJC22100).