Dinuclear Copper(II) Complexes of Two Homologous Pyrazine‐Based Bis(terdentate) Diamide Ligands

摘要: The 1:1 reactions of the new bis(terdentate) diamide ligand N,N'-bis(2-pyridylmethyl)pyrazine-2,5-dicarboxamide (H 2 L 1 ) and its higher homologue N,N'-bis[2-(2-pyridyl)ethyl]-pyrazine-2,5-dicarboxamide with Cu(BF 4 .4 H O in absence added base have consistently afforded dicopper(II) complexes doubly deprotonated ligands (L - . complex [Cu I )(H O) (MeCN) ](BF (2a) has been structurally characterised. Subsequently, employing a correct stoichiometric 2:1 metal-to-ligand ratio MeCN bulk samples dinuclear complexes. compounds )(MeCN) .H (1a.H )(H20)4(BF ].2H (2b.2H While 1a.H lower exhibits very weak antiferromagnetic spin coupling (J = -0.24 cm ), 2b ferromagnetic +0.67 ). EPR studies carried out on polycrystalline powders frozen DMF solutions 2b.2H O. spectra indicate presence dipolar broadening intermolecular exchange, while those are characteristic dipolar-coupled Cu" pairs within molecules, no evidence intra- or exchange. spectral simulations confirm that binuclear structure Cu...Cu distances retained solution. Dinuclear SiF 6 containing compounds, (Cu (Ll)(H ](SiF (1b) {[Cu (μ-SiF )].4H O} (1c.4H O), were obtained serendipitously, nearly quantitative yield, by reaction unexpected anions generated course partial hydrolysis BF employed, thus forming traces HF which reacted glassware.