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[Cu12(CN)18]·2DMF}∞, 1, and {[Ln(DMF)8][Cu6(CN)9]·2DMF}∞
(Ln = Eu, 2; Gd, 3; Er, 4) were obtained from the one step reaction of LnCl3 (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 Ln3+ cations, and
the zeolite-like anionic network is unique. A two step procedure that employs the same components generates the
layer structure {Ln(DMF)4Cu2(CN)5}∞ (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 LnCl3 and KCN. The crystal structure of {K(DMF)2Cu(CN)2}∞ (8) provides insight
into the proposed reaction pathways for forming these two different structural types.

以DMF（N,N-二甲基甲酰胺）为反应溶剂，将LnCl₃（Ln=La、Eu、Gd、Er）与CuCN、KCN进行一步法反应，得到了包合配合物{[La(DMF)₉]₂[Cu₁₂(CN)₁₈]·2DMF}∞（化合物1）以及{[Ln(DMF)₈][Cu₆(CN)₉]·2DMF}∞（其中Ln=Eu时为2，Gd时为3，Er时为4）。
该类配合物由三维Cu−CN阴离子骨架构成，阳离子[Ln(DMF)ₓ]³⁺（x=8、9）填充于骨架的空腔之中。此类配合物被认为是首例包合Ln³⁺阳离子的体系，其类沸石型阴离子骨架结构具有独特性。
采用相同反应组分通过两步法反应，可得到层状结构配合物{Ln(DMF)₄Cu₂(CN)₅}∞（其中Ln=La时为5，Gd时为6，Er时为7），该配合物的五元环重复单元包含Cu−CN−Ln与Cu−CN−Cu两种连接方式，此种连接模式此前尚无先例。
此外，也可通过CuCl与LnCl₃、KCN反应制备此类包合配合物。
配合物{K(DMF)₂Cu(CN)₂}∞（化合物8）的晶体结构，为阐明这两种不同结构类型的潜在反应路径提供了关键依据。