Lanthanide complexes with a new luminescent iminophosphonamide ligand bearing phenylbenzothiazole substituents.

A new iminophosphonamine Ph 2 P(HNPbt)(NPbt) (1, HL) bearing chromophore 2-(phen-2'-yl)-1,3-benzothiazole (Pbt) substituents was synthesized and introduced into lanthanide complexes. It was found that salt metathesis reactions between KL (2) generated in situ and LnCl 3 lead to the formation of tris-iminophosphonamide complexes [LnL 2 ]L (Ln = Y (3), Sm (4), Gd (5), Dy (6)), regardless of the 2/LnCl 3 ratio. Compounds 3-6 consist of a cationic fragment [LnL 2 ] + , where the lanthanide atom is surrounded by two rigidly κ 4 -coordinated ligands, and an L - anion residing in the outer coordination sphere. Iminophosphonamine 1 shows a rare excitation wavelength-dependent two-band luminescence in the solid state. For compounds containing the deprotonated form, namely potassium salt KL and complexes of Gd and Dy, a single-band luminescence with the color changing from turquoise to orange was observed. The Sm complex reveals a set of a few narrow well-resolved bands corresponding to the f-f transitions against the background of the outer-sphere ligand's emission.