Synthese und Struktur von [Fe(SPh)2(NO)2]- dem „Monomeren“ des Roussinschen Phenylesters/ Synthesis and Structure of [Fe(SPh)2(NO)2]- , the “Monomer” of Roussin’s Phenyl Ester

The complex (Et4N )[Fe(SPh)2(NO)2] (2) has been obtained as black crystals by treatment of K[Fe4S3(NO)7]·H2O with potassium hydroxide in molten diphenyldisulfide and subsequent addition of methanol and tetraethylammonium chloride. 2 is orthorhombic, space group Pbca, Z = 8, with a = 18.853(3), b = 17.958(3), and c = 13.283(2) Å at 140 K. The X-ray structure of 2 has been refined to R1 (R2) = 2.7% (3.1% ). It reveals a pseudotetrahedral S2N2 arrangement around the iron atom (Fe -S 2.280, Fe -N 1.679 Å (mean values), S -Fe -S 109.73(2)°, N -Fe -N 117.36(9)°) and Fe -N -O groups of the linear type (N -O 1.180 Å , Fe -N - O 169.0° (mean values)). The N - O bond order is 2.2. Structural properties as well as the low Mößbauer isomeric shift ( + 0.08 mm/s relative to Fe metal) are indicative of strong Fe - N π-back bonding and a major contribution of the mesomeric form Fe = N = Ō̱ .

Mößbauer-spektroskopische Untersuchungen am System Fe1+xSb mit NiAs-Struktur/ Mössbauer-spectroscopy in the system Fe1+xSb with NiAs-structure

Measurements in the system Fe1+xSb for 0.13 ≦ x ≦ 0.30 and in the temperature range 10 K ≦ T ≦ 625 K are represented.In the paramagnetic phase one observes a small quadrupole splitting of ΔνQ=0.272 (8) mm/s, independent of the non-stoechiometric portion x. From the temperature dependence of the isomeric shift δ a Debye-temperature θ= (766 ± 100) K was determined. Néel temperatures are found to be about 211 K, varying smoothly with x, according to an increased number of bipyramidal FeII-atoms and therefore a stronger influence of the ferromagnetic coupling with octaedral FeI-atoms. The measured Mössbauer spectra in the antiferromagnetically ordered phase can only be interpreted as a superposition of several magnetic line-sextets, probably due to a variation of the local magnetic field at the site of 57Fe, with different numbers of nearest Fe-atoms. An exact assignment of the analysed fields to the number of nearest Fe-atoms was not possible. The magnetic saturation fields are in between 95 kG and 155 kG increasing with x. The direction of the local fields are found to be parallel to the plane (001) of the NiAs-lattice.

Mössbauer-Effekt am Fe57 in Additions-und Substitutionsverbindungen des Natrium-Nitrosylprussiates / Mössbauer-Effect in Fe57 of Addition and Substitution Compounds of Sodium Nitroprusside

Investigating 21 iron complex compounds of the type [Fe(CN)5NOL]n- or [Fe(CN)5L]3- it was found that isomeric shift, quadrupol splitting, and Goldanskii effect depend on the purity of the compound. Varying the amount of impurity discrepancies between formerly published data could be explained. The Mössbauer spectra of three compounds showed line widths differing from the theoretical value only by a few per cent. This indicated that a very high purity had been achieved. In all cases information about the molecular structure and the bond strength between the central Fe-atom and its ligands was obtained.