Molecular Networks Based on CN Coordination Bonds

This study examines the use of tetrahedral [E(O–C6X4–CN)4]– anions (E = B, Al; X = H, F), which can be synthesized from the reaction of tetrahedral NaBH4/LiAlH4 and HO–C6X4–CN, as anionic linkers for the generation of 2D and 3D crystalline coordination polymer networks. Such polymer networks were obtained by the connection of tetrahedral p-cyanophenoxy aluminate or borate linkers with monocationic metal centers such as Li+, Na+, Ag+, and Cu+. These studies are specifically focused on the synthesis, structure, and stability of such polymers. Additionally, the perfluorinated O–C6F4–CN linker was used to study electronic influences. Salts bearing the perfluorinated [E(O–C6F4–CN)4]– anion decompose into E(O–C6F4–CN)3 and [O–C6F4–CN]–, which is also observed when a Lewis acid such as B(C6F5)3 is added. Moreover, addition of B(C6F5)3 leads to the formation of molecular-ion pairs because the cyano groups are now either completely or partly blocked. The structures of M[Al(O–C6H4–CN)4] (M = Li, Ag, Cu), Na[B(O–C6H4–CN)4], and Li[Al(O–C6F4–CN)4] as well as of the decomposition products Na(O–C6F4–CN), (THF)Al[O–C6H4–CN·B(C6F5)3]3 (THF = tetrahydrofuran), Na[(F5C6)3B·O–C6H4–CN·B(C6F5)3], and Li[NC–C6F4–O–Al{O–C6F4–CN·B(C6F5)3}3] are discussed.