Synthesis and characterization of diverse coordination polymers.: Linear and zigzag chains involving their structural transformation via intermolecular hydrogen-bonded, interpenetrating ladders polycatenane, and noninterpenetrating square grid from long, rigid N,N′-bidentate ligands:: 1,4-Bis[(x-pyridyl)ethynyl]benzene (x=3 and 4)

The long, rigid ligands 1,4-bis[(3-pyridyl)ethynyl]benzene (L1) and 1,4-bis[(4-pyridyl)ethynyl]benzene (L2) were used in the synthesis of 10 new organic-inorganic coordination frameworks, each of them adopting different structural motifs. Synthesis, single-crystal X-ray structure determination, and spectroscopic and thermogravimetric analyses are presented. The reactions between M(NO3)2·xH2O; M = Cd(II), Cu(II), and Co(II); x = 3-6 and Cu(hfac)2·H2O [hfac = bis(hexafluoroacetylacetonato)] with L1 afforded the following one-dimensional zigzag chain structures: [Cd(C20H12N 2)0.5(NO3)(CH3OH)]n (1, monoclinic, C2/c; a = 7.586(1) Å, b = 23.222(1) Å, c = 13.572(1) Å, β= 92.824(1), Z = 4); [{Cu(C20H12N 2)(NO3)2(CH3OH)}·CH 3OH]n (2, orthorhombic, P21212 1; a = 8.589(1) Å, b = 15.766(1) Å, c = 17.501(1) Å, Z = 4); [Co(C20H12N2) 2(NO3)2(H2O)2] (5, triclinic, P1; a = 7.493(1) Å, b = 8.948(1) Å, c = 14.854(1) Å, α= 100.427(1), β = 97.324(1), γ = 110.901(1), Z = 1); [Cu(C20H12N2)(hfac)2]n (4, monoclinic, C2/c, a = 18.828(1) Å, b = 14.671(1) Å, c = 13.427(1) Å, β = 90.447(1)°, Z = 4). Moreover, the minority phase compound formed from Cu(NO3)2·3H2O and L1 yielded a metallocyclic chain structure, [Cu(C20H 12N2)(NO3)]n (3, triclinic, P1; a = 8.728(1) Å, b = 10.018(1) Å, c = 11.893(1) Å, α = 109.991(1), β= 97.109(1), γ = 115.542(1), Z = 1). In addition to the dinuclear coordination complex 5, all other polymeric structures (1-4) from L1 are composed of interpenetrating 2D and 3D cross-linked zigzag chains via hydrogen-bonding interactions. The reactions between M(NO3) 2·XH2O; M = Cd(II), Cu(II), and Co(II); x = 3-6 and Cu(hfac)2·H2O [hfac = bis(hexafluoroacetylacetonato)] and L2 were dependent on the nature of the metal center and resulted in the formation of four different interpenetrating and noninterpenetrating compounds (6-10): [Co(C20H12N 2)1.5(NO3)2]n (6, triclinic, P1; a = 14.172(1) Å, b = 15.795(1) Å, c = 18.072(1) Å, α = 115.380(1), β = 101.319(1), γ = 93.427(2), Z = 4), which consists of T-shaped building blocks assembled into three-dimensional interpenetrating polycatenated ladders; [Cd(C20H12N 2)2(NO3)2]n (7, monoclinic, 12/a; a = 11.371 (1) Å, b = 20.311 (2) Å, c = 15.240(2) Å, β = 100.201 (2)°, Z = 4), which adopts a two-dimensional noninterpenetrating square-grid motif; [Cu(C20H12N 2)(hfac)2]n (8, monoclinic, /2/a; a = 11.371(1) Å, b = 20.311(2) Å, c = 15.240(2) Å, β= 100.201(2)°, Z = 4), composed of three sets of distinct one-dimensional linear chains; [Cu(C20H12N2)(EtOH)(NO3) 2] [Cu(C20H12N2) 1.5(NO3)2]·2EtOH (9, triclinic, P1; a = 12.248(2) Å, b = 13.711(3) Å, c = 18.257(4) Å, α = 108.078(4)°, β = 97.890(4)°, γ = 103.139(5)°, Z = 2) and [Cu(C20H12N2)(MeOH)(NO3) 2] [Cu-(C20H12N2) 1.5(NO3)2]·2MeOH (10, triclinic, P1; a = 12.136(1) Å, b = 13.738(2) Å, c = 17.563(3) Å, α = 107.663(3)°, β = 94.805(4)°, γ = 104.021(4)°, Z = 2). Both 9 and 10 stack into infinite interpenetrating ladders through bundles of infinite chains and are described in our preliminary communication. © 2005 American Chemical Society.