Metal complexes of 1,10-phenanthroline derivatives. IX. 5T2 ↔ 1A1 spin transitions in iron(II) complexes of 2-(1,10-phenanthrolin-2-yl)thiazole derivatives

Abstract

The preparation of the tridentate chelating agents 2-(1,10- phenanthrolin-2-yl)thiazole, 2-(1,10-phenanthrolin-2-yl)-4-(2- pyridyl)thiazole 2-(1,10-phenanthrolin-2-yl)thiazolidine and 2-(1,10- phenanthrolin-2-yl)benzothiazole is described. Data from the spectra of the bis-ligand nickel complexes indicate that the ligands all have field strengths in the iron(II) crossover region. The temperature dependence of the magnetism of the bis-ligand iron(II) complexes reveals that, except for the complexes of the pyridylthiazole, a smooth, temperature-induced 5T2 ↔ 1A1 transition occurs in these compounds. For no complex is the transition complete within the experimental temperature range (83-363 K). The complex of the pyridylthiazole is high-spin throughout the range, the uncoordinated pyridyl group hindering the close approach of ligand and metal atom necessary for spin-pairing. The ability of the other ligands to induce a spin transition is primarily a consequence of distortions in the environment about the metal atom arising from coordination of the five- membered thiazole or related ring.

Spin Crossover in a Series of Iron(II) Complexes of 2-(2-Alkyl-2H-tetrazol-5-yl)-1,10-phenanthroline: Effects of Alkyl Side Chain, Solvent, and Anion

“…Following this strategy, 2-(2 H -tetrazol-5-yl)-1,10- phenanthroline is designed, which includes two basic SCO components, i.e., tetrazole and 1,10-phenanthroline. Similar tridentate ligands, such as oxadiazole, thiazole, imidazoline, pyrazole, or triazole attached with 1,10-phenanthroline, have been reported by Goodwin et al, but only simple SCO properties are observed in the corresponding isolated iron(II) complexes. Herein, we report the syntheses and characterizations of an extensive series of iron(II) complexes using 2-(2 H -tetrazol-5-yl)-1,10-phenanthroline and its alkyl-substituted derivatives as ligands.…”

Chromium(III) complexes bearing 2-benzazole-1,10-phenanthrolines: synthesis, molecular structures and ethylene oligomerization and polymerization

“…The synthesis of ligands L1, L2 and L5-L7 were reported in our previous paper, 57,58 meanwhile the ligand L9 was synthesized according to the literature. 62 Toluene was refluxed over sodium-benzophenone and distilled under nitrogen prior to use. Dichloromethane was distilled under nitrogen from CaH 2 .…”

“…The organic compounds used as ligands L1, L2 and L5-L7 were efficiently synthesized according to our reported procedures 57, 58 while the ligand L9 was synthesized according to the literature. 62 Following literature procedures, compounds L3 and L4 used as ligands were obtained in acceptable yields (Scheme 1) 57 while ligand L8 58 was prepared in a better yield and ligand L10 62 in even better yield (Scheme 2). corresponding complexes C1-C10 (Scheme 3), which were isolated as stable green solids in high yields (about 76%).…”

Construction of SCO-Active Fe(II) Mononuclear Complexes from the Thio-pybox Ligand

“…Owing to the progress in heterocycle synthetic chemistry, numerous pincer-type ligands composed of pyridine and other nitrogen-containing heterocycles have been designed and synthesized (Chart ). Some mononuclear Fe II and Co II complex families from these ligands, such as tpy and its derivatives, − phenthiazole, phentetrazol, Schiff base ter-imines, , (2-thia) 2 py, , (4-thia) 2 py, (2-thia)­py 2 , 1-bpp, ,, 3-bpp, − and trim were proven to be SCO-active.…”