Spin Control in Ladderlike Hexanuclear Copper(II) Complexes with Metallacyclophane Cores

Two new hexanuclear oxamatocopper(II) complexes 3 and 4 have
been synthesized from the binuclear copper(II) complexes of the
meta- and para-phenylenebis(oxamate) ligands, respectively.
Complexes 3 and 4 possess an overall ladderlike structure made
up of two oxamate-bridged linear trinuclear units (“rails”) connected
through two phenylenediamidate bridges (“rungs”) between the
central copper atoms to give metallacyclic cores of the meta- and
para-cyclophane type, respectively. They show different ground
spin states, S = 1 (3) or S = 0 (4), depending on the substitution
pattern in the aromatic spacers. The triplet state molecule 3
containing two spin doublet CuII3 units connected by two m-phenylenediamidate bridges represents a successful extension of
the concept of “ferromagnetic coupling units” to metal complexes,
which is a well-known approach toward high spin organic radicals.

两种新的六核氧化偶氮铜(II)配合物3和4分别由对位和间位苯二亚胺氧酸配体的双核铜(II)配合物合成而成。配合物3和4整体呈现类似梯状的结构，由两个由氧酸配体桥连的线性三核单元（“轨道”）通过两个苯二胺酸盐桥（“横档”）连接中央铜原子，从而形成分别对应于对位和间位环状芳烃的金属环状核心。它们显示出不同的基态自旋状态，S = 1（3）或S = 0（4），这取决于芳香族间隔基的取代模式。三重态分子3含有两个通过两个m-苯二胺酸盐桥连接的自旋双态CuII3单元，这代表了对“铁磁性耦合单元”概念成功扩展至金属配合物的实践，而该概念是制备高自旋有机自由基的已知方法之一。