Binuclear Copper(I) Macrocycles Synthesized via the Weak-Link Approach

The weak-link approach has been employed to synthesize a series of bimetallic Cu(I) macrocycles in high yield.
Addition of phosphinoalkylether or -thioether ligands to [Cu(MeCN)4]PF6 produces “condensed” intermediates, [μ-(1,4-(PPh2CH2CH2X)2Y)2Cu2][PF6]2 (X = S, O; Y = C6H4, C6F4), containing strong P−Cu bonds and weaker O−Cu or
S−Cu bonds. The weak bonds of these intermediates can be cleaved through ligand substitution reactions to
generate macrocyclic structures, [μ-(1,4-(PPh2CH2CH2X)2Y)2(Z)nCu2][PF6]2 (X = S, O; Y = C6H4, C6F4; Z = pyridine,
acetonitrile, diimines, isocyanide) in nearly quantitative yields. The incorporation of tetrahedral Cu(I) metal centers
into these macrocycles provides a pathway to complexes that differ from analogous d8 square planar macrocycles
generated via this approach in their increased air stability, small molecule reactivity, and ability to form multiple
structural isomers. Solid-state structures, as determined by single-crystal X-ray diffraction studies, are presented
for condensed intermediates and an open macrocycle.