Novel Examples of High-Dimensional Mixed-Valence Copper Cyanide Complexes

The first examples of high-dimensional mixed-valence homometallic cyano-bridged copper complexes were synthesized and characterized:  net-structured [Cu(CN)₄{Cu(cyclam)}_1.5]_2n(H₂O)_5n (1), ladder-type double-chain-structured [Cu(CN)₂{Cu(CN)₂Cu(cyclam)}]_n(H₂O)_n (2), layer-structured [{Cu(CN)₂}₂Cu(cycalm)]_n (3), and hydrogen-bond-based 2-D [Cu(CN)₃Cu(cyclam)]_n(CH₃OH)_n (4) (cyclam = 1,4,8,11-tetraazacyclotetradecane). 1 crystallizes in triclinic space group P1̄ with a = 8.3589(11) Å, b = 13.478(2) Å, c = 14.828(2) Å, α = 66.895(2)°, β = 77.916(3)°, γ = 85.939(3)°, and Z = 1; 2 crystallizes in triclinic space group P1̄ with a = 8.2305(12) Å, b = 9.8861(15) Å, c = 13.219(2) Å, α = 84.863(3)°, β = 75.744(3)°, γ = 89.818(3)°, and Z = 2; 3 crystallizes in monoclinic space group P2₁/c with a = 6.830(2) Å, b = 8.482(2) Å, c = 17.306(4) Å, β = 98.144(4)°, and Z = 2; 4 crystallizes in triclinic space group P1̄ with a = 9.470(1) Å, b = 10.034(1) Å, c = 12.064(1) Å, α = 67.325(2), β = 75.593(2), γ = 70.672(2), and Z = 2. The coordination sphere of Cu^I sites in the complexes shows diverse structures:  tetrahedral [CuC₄] for 1, tetrahedral [CuC₃N] and triangular [CuC₂N] for 2, triangular [CuC₂N] for 3, and triangular [CuC₃] for 4. In particular, 1 constitutes the first example of a structurally characterized system containing a bridging tetrahedral [Cu(CN)₄]^3- unit. The diverse structural nature of these complexes is governed by the capping amines and the content of water in the reaction media. The magnetic interactions are negligible in these mixed-valence complexes.