Mononuclear lanthanide complexes with tetradentate bis(phosphorylamino)-substituted 1,8-naphthyridine ligand: Synthesis and structural studies

Abstract The complexes of 2,7-bis(diphenylphosphorylamino)-1,8-naphthyridine ( L ) with lanthanide nitrates Ln(NO 3 ) 3 (Ln = Nd, Lu) were investigated to elucidate the coordination ability of a novel type of potentially tetradentate ligands – bis(phosphorylamino) substituted naphthyridines. Mononuclear complexes of 1:1 and 1:2 composition, namely, [Nd(L)(NO 3 ) 3 ] ( 1a ), [Nd(L)(NO 3 ) 3 ]·H 2 O ( 1b ), [Lu(L)(NO 3 ) 2 (H 2 O)](NO 3 ) ( 2 ), [Nd(L) 2 (NO 3 ) 2 (H 2 O)](NO 3 ) ( 3 ), [Lu(L) 2 (NO 3 )(H 2 O)](NO 3 ) 2 ·0.75CH 3 CN·H 2 O ( 4a ) and [Lu(L) 2 (NO 3 )(H 2 O)](NO 3 ) 2 ( 4b ) were synthesized and studied by IR, Raman, and 31 P NMR spectroscopy in solid state and in solution. Structures of the complexes 1b and 4a were determined by X-ray diffraction. According to X-ray crystallography, vibrational spectroscopy and C, H, N, P elemental analysis data in solid 1:1 complexes one neutral molecule of L serves most likely as O , O , N , N -tetradentate ligand while in the 1:2 complexes only one ligand molecule coordinates in the same O , O , N , N -tetradentate fashion, and the second one serves as O -monodentate one. In solution the coordination mode of the ligand is preserved in all complexes.