Metal complexes of new bis(tacn) ligands: Syntheses and structures of copper(II) complexes

Three bis(tacn) ligands 3,5-bis(1,4,7-triazacyclonon-1-ylmethyl)biphenyl (Lphx) (1), 3,5-bis(1,4,7-triazacyclonon-1-ylmethyl)benzoic acid (Lcax) (2) and 3,5-bis(1,4,7-triazacyclonon-1-ylmethyl)-nitrobenzene (Lnix) (3) have been synthesised. Reactions of these ligands with two equivalents of Cu(NO3)2·3H2O in the presence of NaOH and NH4PF6 resulted in crystallisation of three distinct product classes, viz (i) polymeric {[Cu2(μ-Cl)2(Lphx)](PF6)2}n (5) in which the Lphx ligand bridges two Cu2 moieties, (ii) tetranuclear [Cu2(μ-OH)(Lcax)]2(NO3)2(PF6)2·2H2O (6) in which two “head to tail” Lcax ligands chelate to two Cu2 moieties, and (iii) dinuclear [Cu2(μ-OH)(μ-Cl)(Lnix)](NO3)(PF6) (7) where the Lnix ligand chelates to a single Cu2 centre.

The syntheses of three novel m-xylene bridged bis(tacn) ligands are described along with the crystal structures of the corresponding copper(II) complexes. The results demonstrate the influence of the substituent on the m-xylene ring, giving tetranuclear or dinuclear sandwich complexes or alternatively a linear coordination polymer with a bridging ligand.Figure optionsDownload as PowerPoint slide