Solid-state and solution characterization of half-sandwich Ru(II) complexes with carboxylic ligands containing N-based coordinating functions

Abstract The aminobenozic ligands 3-(4-aminophenyl)propionic acid (4APPA), 4-(4-aminophenyl)butyric acid (4APBA) and 5-aminoisophthalic acid (5AIPA) have been reacted with [(η 6 -p-cymene)RuCl 2 ] 2 giving rise to the corresponding half-sandwich Ru(II) complexes of formula [(η 6 -p-cymene)Ru(ligand)Cl 2 ] ( 1 , 2 and 3 , respectively). The solid state structures of all three organometallic compounds have been elucidated by single crystal X-ray analysis conducted on crystals grown in MeOH or THF. The aminobenzoic ligands interact with the metal through the amine function, the pseudo-octahedral geometry being satisfied by a η 6 -coordinated p-cymene ring and by two chloride ligands. Dissolution of the complexes in coordinating solvents, such as dmso or acetonitrile led to ligand solvolysis, as evidenced by 1 H NMR analysis. The lability of monodentate N-based ligands toward the organometallic fragment [(η 6 -p-cymene)RuCl 2 ] was evidenced by the structural outcomes deriving from crystals grown in acetonitrile of the related compounds [(η 6 -p-cymene)Ru(INA)Cl 2 ] ( 4 ) (INA = isonicotinic acid) and [(η 6 -p-cymene)Ru(4ABA)Cl 2 ] ( 5 ) (4ABA = 4-aminobenzoic acid). These revealed, although in low yields, the occurred ligand solvolysis with formation of a cocrystal of formula {[(η 6 -p-cymene)Ru(INA)Cl 2 ](H 2 O) (INA)} in the case of complex 4 and formation of the tetrakis–acetonitrile complex trans-[Ru(CH 3 CN) 4 Cl 2 ] in the case of complex 5 .