Cyanide-bridged mixed-valence copper(II/I) coordination polymers: Unique 7-connected sev-type 3D network versus anionic 2D host network encapsulated with cationic complex

• Two mixed-valence Cu(II/I) complexes were synthesized via different cyanide resources under solvothermal reaction conditions.
• Compound 1 containing uncommon semi-closed {Cu2(CN)3} dimer, and showing the first example of uninodal 7-connected sev-like cyanide-bridged network.
• Compound 2 is a honeycomb-like 2D anionic layer, in which [CuII(H2O)4]2 + cations are encapsulated into alternate interlamellar space.
• Two compounds show differently characteristic properties related with their unique whole structure.

Reactions of CuCl2, K2[Ni(CN)4]/K3[Co(CN)6], and 5-amino-1H-tetrazole led to cyanide-bridged mixed-valence Cu(II/I) complexes, [Cu(H2O)3Cu3(CN)5] (1) and [Cu(H2O)4][Cu4(CN)6] (2).The uncommon semi-closed {Cu2(CN)3} dimmers in 1 are bridged by μ3-C,C,N cyanide ligands to afford rare 1D centipedal-like chain motifs, which are further bridged by μ2-C,N and metalloligand “CN–Cu(4)–CN” to finish sophisticated zeolite-like 3-D structure. Topologically, 1 is the first example of uninodal 7-connected sev-like cyanide-bridged network. Compound 2 consists of two-dimensional honeycomb-related anionic layers [Cu4(CN)6]2 −, within which the [Cu(H2O)4]2 + cations are intercalated into alternate interlamellar space. Compound 1 shows antiferromagnetic couple arising from pure ground-state configuration of Cu(II) mediated by diamagnetic bridges –CN–CuI–CN −. The inclusion compound 2 shows blue photoluminescence originated from Cu(I) center to the unoccupied π* orbital of the cyanide ligand (MLCT) charge transfer.

Graphical abtractCyanide-bridged mixed-valence Cu(II/I) complexes [Cu(H2O)3Cu3(CN)5] (1) and [Cu(H2O)4][Cu4(CN)6] (2) have been synthesized and characterized. Compound 1 is the first example of uninodal 7-connected sev-like open framework, constructed by uncommon semi-closed trinuclear subunits and bridging cyanide ligands, and representing weak antiferromagnetic coupling of the CuII ions mediated by the –NC–CuI–CN– diamagnetic bridges. For compound 2, unique cationic guests [Cu(H2O)4]2 + are encapsulated in the anionic host framework [Cu4(CN)6]2 −, which shows photoluminescence property induced from MLCT.Figure optionsDownload as PowerPoint slide