Polynuclear Iron-Oxo/Hydroxy Complexes of Ketoacidoximate Ligands: Synthesis, Structures and Conversion to Ferric Oxide

Abstract

The polynuclear iron-oxo/hydroxy complexes containing ketoacidoximate ligands described in this report are [Fe 3 6 (3) (dmso = dimethyl sulfoxide). 1-3 are isolated from the reaction of Fe(NO 3 ) 3 ·9H 2 O and in situ generated anions of ketoacidoximate ligand [(HO 2 C-C(R 1 ) = NOR 2 ), where R 1 = CH 3 , C 6 H 5 and CH 2 -C 6 H 5 ; R 2 = H or CH 3 ] in H 2 O, followed by crystallization in donor solvents. 1-3 undergo thermal decomposition above 200 8C and form crystalline a-Fe 2 O 3 at 600 8C.

All-inorganic ferric wheel based on hexaniobate-anion linkers

“…19 At the same time, high-nuclearity iron clusters feature a variety of structures, including cyclical metalloorganic coordination compounds. [20][21][22][23][24] For example, Shanmugam reported the [Fe III 8 (μ-O) 4 (L 2− ) 8 ] ferric wheel, 23 where L = Schiff-base, and Hung reported [Fe III 10 (bdtbpza) 10 (MeO) 20 ] 24 where bdtbpza = bis(3,5-di-tert-butylpyrazol-1-yl). Now, using a modification of the second synthetic approach discussed above, we report the first example of a high-nuclearity iron coordination cluster containing intact hexaniobate moieties in the form of a ferric wheel, Li 48 [(Nb 6 O 19 ) 8 Fe III 8 (OH) 8 ]• 88H 2 O (1), which is the largest iron-niobate cluster known to date and the first example of an all-inorganic ferric wheel.…”

“…19 At the same time, high-nuclearity iron clusters feature a variety of structures, including cyclical metallo–organic coordination compounds. 20–24 For example, Shanmugam reported the [Fe III 8 (μ-O) 4 (L 2− ) 8 ] ferric wheel, 23 where L = Schiff-base, and Hung reported [Fe III 10 (bdtbpza) 10 (MeO) 20 ] 24 where bdtbpza = bis(3,5-di- tert -butylpyrazol-1-yl).…”