Cyanide-Bridged Lanthanide(III)−Transition Metal Extended Arrays:  Interconversion of One-Dimensional Arrays from Single-Strand (Type A) to Double-Strand (Type B) Structures. Complexes of a New Type of Single-Strand Array (Type C)

A series of one-dimensional arrays of lanthanide−transition metal complexes has been prepared and characterized. These complexes, {(DMF)₁₀Ln₂[Ni(CN)₄]₃}_∞, crystallize as linear single-strand arrays (structural type A) (Ln = Sm, 1a; Eu, 2a) or double-strand arrays (structural type B) (Ln = Sm, 1b; Eu, 2b) depending upon the conditions chosen, and they are interconvertible. The single-strand type A structure can be converted to the double-strand type B structure. When the 1b and 2b type B crystals are completely dissolved in DMF, their infrared spectra are identical to the infrared spectra of 1a and 2a type A crystals dissolved in DMF. These solutions produce type A crystals initially. It is believed that formation of the type A structure is kinetically favored while the type B structure is thermodynamically favored for lanthanide−nickel complexes 1 and 2. On the other hand the complex {(DMF)₁₀Y₂[Pd(CN)₄]₃}_∞, 3, appears to crystallize only as the double-strand array (type B). The complexes {(DMF)₁₂Ce₂[Ni(CN)₄]₃}_∞, 4, and {(DMF)₁₂Ce₂[Pd(CN)₄]₃}_∞, 5, crystallize as a new type of single-strand array (structural type C). This structural type is a zigzag chain array. Crystal data for 1a:  triclinic space group P1̄, a = 10.442(5) Å, b = 10.923(2) Å, c = 15.168(3) Å, α = 74.02(2)°, β = 83.81(3)°, γ = 82.91(4)°, Z = 2. Crystal data for 1b:  triclinic space group P1̄, a = 9.129(2) Å, b = 11.286(6) Å, c = 16.276(7) Å, α = 81.40(4)°, β = 77.41(3)°, γ = 83.02(3)°, Z = 2. Crystal data for 2a:  triclinic space group P1̄, a = 10.467(1) Å, b = 10.923(1) Å, c = 15.123(1) Å, α = 74.24(1)°, β = 83.61(1)°, γ = 83.13(1)°, Z = 2. Crystal data for 2b:  triclinic space group P1̄, a = 9.128(1) Å, b = 11.271(1) Å, c = 16.227(6) Å, α = 81.36(2)°, β = 77.43(2)°, γ = 82.99(1)°, Z = 2. Crystal data for 3:  triclinic space group P1̄, a = 9.251(3) Å, b = 11.193(4) Å, c = 16.388(4) Å, α = 81.46(2)°, β = 77.18(2)°, γ = 83.24(3)°, Z = 2. Crystal data for 4:  triclinic space group P1̄, a = 11.279(1) Å, b = 12.504(1) Å, c = 13.887(1) Å, α = 98.68(1)°, β = 108.85(1)°, γ = 101.75(1)°, Z = 2. Crystal data for 5:  triclinic space group P1̄, a = 11.388(3) Å, b = 12.614(5) Å, c = 13.965(4) Å, α = 97.67(3)°, β = 109.01(2)°, γ = 101.93(2)°, Z = 2.