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-.