A Layered, Piedfort-Aggregated Cu(I) Isocyanide Coordination Network Derived from an Encumbering Tritopic Linker

Isocyanide coordination networks (^ISOCNs) are emerging as a distinct class of framework materials capable of organizing low-valent metal centers into metal-organic framework (MOF)-type structural building units (SBUs). To date, most of the reported ^ISOCN materials have employed linear ditopic diisocyanide linkers. In an effort to expand linker architectures associated with ^ISOCN formation, reported here is the synthesis of the encumbering tritopic isocyanide linker (CNAr^Dipp2)₃Ar³ (Ar^Dipp2 = 2,6-(2,6-(i-Pr)₂C₆H₃)₂C₆H₂; Ar³ = 1,3,5-(C₆H₄)₃C₆H₃) and its ability to produce network materials with Cu(I) centers. Treatment of (CNAr^Dipp2)₃Ar³ with [Cu(NCMe)₄]PF₆ in THF under solvothermal conditions produced single crystals of the new network, Cu^ISOCN-6, which possesses cationic [Cu(THF)(CNAr^Dipp2)₃]⁺ SBUs linked by a triphenylbenzene core. The lattice structure of Cu^ISOCN-6 revealed a noninterpenetrated two-dimensional honeycomb sheet corresponding to an hcb (6,3) net. The honeycomb sheets of Cu^ISOCN-6 are stacked in an offset, six-layer repeating pattern that possess distinct piedfort aggregates assembled via noncovalent π-π stacking interactions between the triphenylbenzene core of the (CNAr^Dipp2)₃Ar³ linker. The piedfort aggregate structural elements compress the lattice structure of Cu^ISOCN-6 such that it is dense packed and nonporous, as determined via gas sorption measurements. However, Cu^ISOCN-6 possesses considerable thermal and chemical stability on account of interlayer piedfort association.