Synergetic spin singlet–quintet switching and luminescence in mononuclear Fe(ii) 1,3,4-oxadiazole tetradentate chelates with NCBH₃ co-ligand

Abstract

We report the multi-step synthesis of tetradentate 2-(Naphthalen-2-yl)-5-[N,N-bis(2-pyridylmethyl)aminomethyl]-1,3,4-oxadiazole (LTetra-ODA) along with its corresponding [FeII(LTetra-ODA)(NCBH3)2].1.5CH3OH (C1) complex which is the first mononuclear 1,3,4 oxadiazole based Fe(II) spin crossover (SCO) complex and...

A combined theoretical and experimental approach to determine the right choice of co-ligand to impart spin crossover in Fe(ii) complexes based on 1,3,4-oxadiazole ligands

“…The two ligands 2-(2-pyridyl)-5-[ N , N -bis(2-pyridylmethyl)aminomethyl]-1,3,4-oxadiazole ( L TetraPy–ODA ) and 2-phenyl-5-[ N , N -bis(2-pyridylmethyl)aminomethyl]-1,3,4-oxadiazole ( L TetraPh–ODA ) were synthesised in high yields according to the ligand synthesis of L Tetra–ODA , reported previously by some of us. 24 The main modification to the procedure was the use of appropriate pyridine-2-carboxylic acid hydrazide in the case of L TetraPy–ODA and phenyl-2-carboxylic acid hydrazide in the case of L TetraPh–ODA (Scheme 1). Both ligands were obtained in high yields 67% and 78%.…”

“…In all the cases the two monodentate co-ligands are coordinated in the cis fashion similar to the [Fe( L Tetra–ODA )(NCBH 3 ) 2 ]·1.5 CH 3 OH complex reported by some of us earlier. 24…”

“…23 Finally, some of us could recently report the first mononuclear Fe( ii ) spin crossover complex based on a tetradentate 1,3,4 oxadiazole ligand with two monodentate NCBH 3 − co-ligands [Fe( L Tetra–ODA )(NCBH 3 ) 2 ]·1.5 CH 3 OH, where L Tetra–ODA is the tetradentate 2-(naphthalen-2-yl)-5-[ N , N -bis(2-pyridylmethyl)aminomethyl]-1,3,4-oxadiazole ligand. 24 Given the extended pi system of the naphthalic substituent, which is known to be an antenna component in photoactive systems, the luminescence property of the complex, along with the synergistic effects of luminescence and spin crossover behaviour was investigated for this compound. 24 In the present manuscript, the tetradentate binding pocket of the previously reported ligand is kept constant, but the naphthalene moiety of the previously reported analogue is changed to pyridine and phenyl to investigate in more detail the effect of it on the SCO behaviour.…”

“…24 Given the extended pi system of the naphthalic substituent, which is known to be an antenna component in photoactive systems, the luminescence property of the complex, along with the synergistic effects of luminescence and spin crossover behaviour was investigated for this compound. 24 In the present manuscript, the tetradentate binding pocket of the previously reported ligand is kept constant, but the naphthalene moiety of the previously reported analogue is changed to pyridine and phenyl to investigate in more detail the effect of it on the SCO behaviour. The incorporation of pyridine in the ligand backbone also facilitated the synthesis of a new dinuclear Fe( ii ) complex based on 1,3,4-oxadiazole.…”

Luminescent Cadmium(II)-Based 12-MC-4 Metallacrown Complex with 2-Methylmercaptobenzohydroxamic Acid Ligand

“…During this process, the lattice DMF molecules present in the crystal lattice might have evaporated and the void spaces in the crystal lattice filled with water molecules from the atmosphere. This is described more often in the literature [27][28][29][30][31].…”