Two distinct Ln(III)-Cu(I) cyanide extended arrays: structures and synthetic methodology for inclusion and layer complexes

Encapsulation complexes formulated as {La(DMF)(9)](2)Cu(12)(CN)(18)].2DMF}(infinity), 1, and {Ln(DMF)(8)]Cu(6)(CN)(9)].2DMF}(infinity) (Ln = Eu, 2; Gd, 3; Er, 4) were obtained from the one step reaction of LnCl(3) (Ln = La, Eu, Gd, Er) with CuCN and KCN in DMF. They consist of a three-dimensional Cu-CN anionic array with pockets occupied by the cation, Ln(DMF)(x)](3+) (x = 8, 9). These complexes are believed to be the first examples of encapsulated Ln(3+) cations, and the zeolite-like anionic network is unique. A two step procedure that employs the same components generates the layer structure {Ln(DMF)(4)Cu(2)(CN)(5)}(infinity) (Ln = La, 5; Gd, 6; Er, 7) in which the five-membered ring repeating unit has Cu-CN-Ln and Cu-CN-Cu linkages which are also without precedent. Encapsulation complexes can also be prepared from CuCl, reacting with LnCl(3) and KCN. The crystal structure of {K(DMF)(2)Cu(CN)(2)}(infinity) (8) provides insight into the proposed reaction pathways for forming these two different structural types.