Synthesis, structure, and photoluminescent properties of lanthanide (Ln = Dy, Tb) chlorides and thiophenolates supported by formamidinate ligands

The [Dy(DippForm)₂Cl(THF)] (1a) and [Tb(DippForm)₂Cl(THF)₂] (1b) complexes are synthesized using salt metathesis reactions between lanthanide chlorides and K(DippForm) (DippForm = N,N′-bis(2,6-diisopropylphenyl)formamidinate). In contrast to K(DippForm), a reaction of its less sterically demanding analogue K(MesForm) (MesForm = N,N′-bis(mesityl)formamidinate) with LnCl₃ at any ratio of the reagents leads to the formation of the homoligand [Ln(MesForm)₃] (Ln = Dy (2a), Tb (2b)) complexes. The [Ln(MesForm)₂Cl(THF)] compounds are not isolated. Compounds 1a and 1b are successfully used as starting reagents for the preparation of new thiophenolate complexes [Ln(DippForm)₂(SPh)(THF)] (Ln = Dy (3a), Tb (3b)). Crystal structures of compounds 1-3 are determined by single crystal X-ray diffraction. Photoluminescent properties of the complexes obtained are studied. The analysis of the spectra of both DippForm^– and SPh^– ligands shows an antenna effect for both Dy(III) and Tb(III). However, MesForm^– acts as an efficient antenna for Tb(III) rather than Dy(III).