Synthesis and characterisation of infinite co-ordination networks from flexible dipyridyl ligands and cadmium salts

Abstract

Crystallisation of flexible dipyridyl ligands with Cd(NO₃)₂·6H₂O or CdSO₄·6H₂O gives co-ordination networks of composition [Cd(NO₃)₂(Py₂CH₂)₂] 1 [Py₂CH₂ = 1,1-bis(4-pyridyl)methane]; [Cd₂(NO₃)₄(Py₂C₃H₆)₄(H₂O)] 2 [Py₂C₃H₆ = 1,3-bis(4-pyridyl)propane]; [Cd₂(SO₄)₂(Py₂C₃H₆)₃(H₂O)_2.7]·4.5H₂O 3; [Cd(NO₃)₂(Py₂C₄H₈)(H₂O)₂] 4 [Py₂C₄H₈ = 1,4-bis(4-pyridyl)butane]; [Cd₂(NO₃)₄(Py₂C₅H₁₀)₃(H₂O)] 5 [Py₂C₅H₁₀ = 1,5-bis(4-pyridyl)pentane] and [Cd(NO₃)₂(Py₂C₆H₁₂)₂] 6 [Py₂C₆H₁₂ = 1,6-bis(4-pyridyl)hexane]. The compounds were characterised by X-ray single crystal diffraction studies. In compounds 1, 2, 4 and 6 the cadmium ions are hexa-co-ordinate with a slightly distorted octahedral geometry. Compounds 3 and 5 both display examples of a less common hepta-co-ordinate cadmium ion geometry. Compounds 2, 3 and 6 exhibit novel modes of interpenetration.