One-dimensional coordination polymers of a flexible bis(pyridylurea) ligand

Abstract

The assembly of a bis(pyridylurea) ligand, N,N′-ethane-1,2-diylbis(3-pyridin-4-ylurea) (L), with Cu(AcO)₂, CuCl₂ or CoSO₄ led to four 1D coordination polymers, {[Cu₂(AcO)₃(OH)L]·2.6H₂O}_n (1), {[CuL₂(H₂O)₂]·2AcO·3CH₃OH}_n (2), {[CuL₂(DMF)₂]·2Cl·2H₂O}_n (3), and {[Co₂L₃(H₂O)₄(CH₃OH)₂]·2SO₄·6H₂O}_n (4). The ligand exhibits the expected flexibility in the formation of the coordination polymers. Compounds 1, 2 and 3 are infinite 1D ribbon-like polymers with metal nodes and flexible ligands in bent/gauche (V-shaped) conformations, while complex 4 shows a 1D ladder structure. Interestingly, the ligand molecules show two different conformations (roughly linear GAG and V-shaped GAA; G = gauche, A = anti) in 4. The tetranuclear copper(II) complex 1 is analyzed by temperature-dependent magnetic measurements, and represents a rare example of a six-coordinate copper complex with an endohedral hydroxide anion.