NEW OXALATO-FLUORO COMPOUNDS OF IRON(III)
Roland Leo, Werner Massa
Fachbereich Chemie der Philipps-Universität, D-35032
Marburg, Germany
E-mail: leo@ax1503.chemie.uni-marburg.de
Keywords: iron(III),
fluoroferrates(III), oxalato-fluoroferrates(III), organic cations
Mixed ligand fluorometallates containing the possibly four-dentate oxalato ligand are interesting candidates for new anionic framework structures, especially when combined with large organic cations. By addition of organic amines piperazine (pipz), diaminobicyclooctane (DABCO) or imidazole (imid) to solutions of Fe(III) in mixed hydrofluoric/oxalic acid and diffusion of ethanole to the mixture three new oxalato-fluoroferrates(III) were obtained (Table). By recrystallization of a corresponding product from DMSO the neutral adduct Fe2F4ox(DMSO)4 was formed. The crystal structures were determined by X-ray diffraction on single crystals. While in 1 and 2 monomeric anions [FeF3ox(H2O)]2- and [FeFox2(H2O)]2- are observed, the DMSO adduct 3 is dimeric and 4 forms a double chain structure (Fig. 1) interesting from a magnetochemical point of view. In contrast to 1 and 2, with pyridinium cations the monomeric [FeF2ox(H2O)2]- anion was found [1].
| DABCOH2[FeF3ox(H2O)].H2O 1 | PipzH2[FeFox2(H2O)].
2H2O 2 |
[Fe2F4ox(DMSO)4]
3 |
(imidH)2[Fe2oxF6]
4 |
| P21/c | P21/n | P21/n | Pban |
| a = 12.924(3) A | a = 9.191(3) A | a = 7.259(2) A | a = 9.143(2) A |
| b = 7.320(1) A | b = 13.163(8) A | b = 11.409(3) A | b = 20.837(6) A |
| c = 15.269(3) A | c = 13.043(6) A | c = 13.374(2) A | c = 3.890(1) A |
| b= 110.07(1)° | b= 104.96(4)° | b= 97.26(1)° | |
| R = 0,0376 | R = 0.0528 | R = 0.0447 | R = 0.0251 |
.
| Fig. 1 Section of the
infinite double-chain anion [Fe2oxF6]2-
in 4. Displacement ellipsoids at the 50%
level. Bridge angle Mn-F-Mn 173.7(2)°. |
|