Pyrazine-bridged dinuclear complex formation by early lanthanides (LaIII, PrIII, NdIII and SmIII) containing bulky fluorinated β-diketonates

The reaction of 1 equivalent of pyrazine (pyz) with two equivalents of Ln(fod)3 units led to isolation of first example of pyrazine-bridged dinuclear lanthanide β-diketonate complexes of the form [Ln(fod)3(μ-pyz)Ln(fod)3] (where fod is the anion of 6,6,7,7,8,8,8-heptafluoro-2,2-dimethyl-3,5-octanedione and Ln = La, Pr, Nd and Sm). Amazingly only early lanthanides form pyrazine-bridged dinuclear Ln(fod)3 complexes, although the entire series was explored. The high yield, elemental analysis and NMR of the isolated complexes strongly support their dinuclear nature. The solution structure of the complexes was investigated by 1H NMR and 4f–4f absorption spectroscopy which confirm their dinuclear nature. The luminescence of Sm–Sm complex, in solution, has been investigated and discussed.