Hexaazamacrocyclic Nickel and Copper Complexes and their Reactivity with Tetracyanoquinodimethane

The hexaazamacrocycle 1,4,7,10,13,16-hexaazacyclooctadecane, [18]ane-N6, forms mono- and dinuclear derivatives with copper chloride depending on the reaction stoichiometries and times. The mononuclear derivative, [Cu([18]ane-N6)]Cl2·H2O, presents the macrocycle wrapped around the metal atom in a distorted octahedral coordinative environment, while the dinuclear derivative, [Cu2([18]ane-N6)Cl2]Cl2·4H2O, is formed by a central Cu2Cl2 core surrounded by an almost planar macrocycle. The crystal structure of both derivatives is stabilized by a network of hydrogen bonds involving the amine macrocyclic groups, the chloride anions, and the crystallization water molecules. The copper atoms in the dinuclear derivative show a strong antiferromagnetic coupling, as expected for the crystal structure parameters. A mononuclear nickel derivative has also been obtained from nickel nitrate by following the same synthetic procedure. These compounds react with TCNQ salts with formation of two types of derivatives, [M([18]ane-N6)](TCNQ)2 and [M([18]ane-N6)](TCNQ)4, depending on the use of radical-anionic or mixed-valence TCNQ salts in the reaction. The crystal structures of the nickel derivatives show that the former derivatives are built up by macrocyclic metal cations surrounded by dimeric dianions (TCNQ)22-, either isolated or stacked along the crystal. The derivative with four TCNQ units/formula consists of alternated chains of metallomacrocyclic cations and stacked TCNQ anions. The crystal parameters suggest that every TCNQ holds approximately 0.5 electrons and overlaps with a neighboring unit to form dimeric monoanions, (TCNQ)2-.六氮杂大环1,4,7,10,13,16-六氮杂环十八烷（[18]ane-N6）可依据反应计量比与反应时间，与氯化铜生成单核及双核衍生物。单核衍生物[Cu([18]ane-N6)]Cl₂·H₂O中，大环于畸变八面体配位环境中包裹金属原子；双核衍生物[Cu₂([18]ane-N6)Cl₂]Cl₂·4H₂O则由中心Cu₂Cl₂核与近乎平面的大环组装而成。两种衍生物的晶体结构均由氢键网络稳定，该网络涉及胺基大环基团、氯离子与结晶水分子。双核衍生物中的铜原子呈现强反铁磁耦合，与晶体结构参数的理论预期一致。采用相同合成路径，以硝酸镍为原料也可制得单核镍衍生物。上述化合物可与四氰基对醌二甲烷(TCNQ)盐发生反应，根据所用TCNQ盐为自由基阴离子型或混合价态型，生成[M([18]ane-N6)](TCNQ)₂与[M([18]ane-N6)](TCNQ)₄两类衍生物。镍衍生物的晶体结构显示，前者由被二聚体二阴离子(TCNQ)₂²⁻包裹的金属大环阳离子构成，该二聚体可独立存在或沿晶体方向堆积。含4个TCNQ单元的衍生物则由金属大环阳离子与堆积的TCNQ阴离子交替链组成。晶体参数表明，每个TCNQ约带有0.5个电子，并与相邻单元发生重叠，进而形成二聚体单阴离子(TCNQ)₂⁻。