Channel-containing structures generated from linear coordination polymer chains containing N,N′-bidentate ligands and Cu-Cu dimetal units

Four new one-dimensional coordination polymers containing the dimetal cluster Cu2(OAc)4 have been synthesized by reacting Cu(OAc)2 ⋅ H2O with two different N,N′-bidentate ligands. Reaction of the flexible ligand, 1,2-bis(4-pyridyl)ethane (L1), with the copper starting material produced two, co-crystallizing coordination polymers: catena-Poly[Cu2(OAc)4(L1)] ⋅ 2H2O (1) and catena-Poly[Cu2(OAc)4(L1)]. In the solid state, 1 (monoclinic, C2/c, a=24.9471(17)Å, b=13.3539(9)Å, c=8.8050(6)Å, β=93.6480(10)°, V=2927.4(3)Å3, Z=4) features linear chains which are organized into layers. These layers stack along the crystallographic c-axis forming small hexagonal channels occupied by the solvent of crystallization. Compound 2 (triclinic, P-1, a=7.6263(6)Å, b=8.5283(6)Å, c=9.8633(6)Å, α=74.1070(10)°, β=68.2160(10)°, γ=74.0090(10)°, V=561.96(7)Å3, Z=1) also features linear chains of the coordination polymer, but differs from 1 in that the chains are packed so as to leave no significant channels. Reaction of the rigid ligand, 1,4-bis(4-pyridyl)buta-1,3-diyne (L2), with the copper starting material also afforded two co-crystallizing coordination polymers: catena-Poly[Cu2(OAc)4(L2)] (3) and catena-Poly[Cu2(OAc)4(L2)] ⋅ solvents (4). 3 (monoclinic, P21/m, a=9.8065(9)Å, b=12.3793(11)Å, c=9.9408(9)Å, β=107.6009(17)°, V=1150.29(18)Å3, Z=2), like 2, features linear chains and contains no significant solvent accessible void space. 4 (monoclinic, C2/c, a=28.9810(16)Å, b=12.9301(7)Å, c=8.6954(5)Å, β=98.8010(10)°, V=3220.0(3)Å3, Z=4) also consists of linear chains of the coordination polymer. However, the overall topology of 4 is identical to that of 1, with the generated hexagonal channels containing crystallographically unidentifiable solvents of crystallization. Compounds 1 and 2 and compounds 3 and 4 are pairs of polymorphic coordination polymers neglecting the solvents of crystallization in 1 and 4. The compounds, which represent four new examples of coordination polymers containing dimetal units, have been characterized by IR, elemental analysis, and thermogravimetric analysis in addition to X-ray crystallography.