Three Chiral Cyanide-Bridged Cr–Cu Complexes: Synthesis, Crystal Structures and Magnetic Properties

Xia Chen,Wen-Long Lan,Lu Yang,Dao-Peng Zhang,Yu Liu,Xiao-Yun Hao,Wei-Jiang Si,Shu-Juan Zhuang,Qing-Yun Liu,Zhen Zhou

doi:10.17344/acsi.2018.4790

Abstract

Two trans-dicyanidochromium(III)-containing building blocks and one chiral copper(II) compound have been employed to assemble cyanide-bridged heterometallic complexes, resulting in three chiral cyanide-bridged Cr(III)-Cu(II) complexes, [Cu(L1)2Cr(L3)(CN)2]ClO42 · CH3OH · H2O (1a, L1 = (S,S)-1,2-diaminocyclohexane, H2L3 =1,2-bis(pyridine- 2-carboxamido)benzene), [Cu(L2)2Cr(L2)(CN)2]ClO42 · CH3OH · H2O (1b, L2 = (R,R)-1,2-diaminocyclohexane) [Cu(L3)2Cr(L4)(CN)2][Cr(L4)(CN)2] · CH3OH · 2H2O (2), (H2L4 = 1,2-bis(pyridine-2-carboxamido)-4-chlorobenzene). All the three complexes have been characterized by elemental analysis, IR spectroscopy and X-ray structure determination. Single-crystal X-ray diffraction analysis shows that the two enantiomeric complexes 1a, 1b and the complex 2 belong to cyanide-bridged cationic binuclear structure type with ClO4 - or the anionic cyanide building block as balance anion for complexes 1a, 1b or 2, respectively. Investigation of the magnetic properties of the complexes 1a and 2 reveals the weak ferromagnetic coupling between the neighboring Cr(III) and Cu(II) ions through the bridging cyanide group.

Highlights

Molecular-based magnetic materials have attracted widespread attention in the past few decades due to their potential applications in high-density information storage and quantum tunneling effects.[1,2,3,4] During the process of the synthesis of the new magnetic complexes, the choice of magnetic spin carriers, bridging bonds and coordination ligands plays a very important role on the structure and the functional property of the target magnetic complexes
In order to find new chiral molecular magnetic complexes and further enrich the low-dimensional cyanide bridged trans-dicyano-based compounds, we investigated the reactions of trans-dicyanidochromium(III) precursors with chiral organic amine copper compounds (Scheme 1) and obtained three new cyanide-bridged chiral Cr(III)-Cu(II) complexes, including the two enantiomeric complexes {[Cu(L1/L2)2Cr(L3)(CN)2]ClO4}2 · CH3OH · H2O (1a, 1b), and {[Cu(L2)2Cr(L4)(CN)2][Cr(L4)(CN)2]} · CH3OH · 2H2O (2)
The recent works have proved that trans-dicyanometallates are good building blocks for synthesizing cyanide-bridged magnetic complexes.[33,34,35,36,37,38]

Summary

Introduction

Molecular-based magnetic materials have attracted widespread attention in the past few decades due to their potential applications in high-density information storage and quantum tunneling effects.[1,2,3,4] During the process of the synthesis of the new magnetic complexes, the choice of magnetic spin carriers, bridging bonds and coordination ligands plays a very important role on the structure and the functional property of the target magnetic complexes. In order to clearly clarify the magnetic structure correlation in low-dimensional magnetic systems and to prepare interesting low-dimensional molecular magnetic materials, a series of cyanide precursors containing the larger equatorial in-plane ligands and two trans-cyanide groups have been designed.[33,34,35,36,37,38] Studies have shown that these types of cyanide-containing precursors were good choices for assembling cyanide bridged bimetallic magnetic complexes with different structures, such as multinuclear, nanomolecular and one-dimension-.

Experimental

1. General Procedures and Materials

Results and Discussion

Conclusion