We report a pulsed EPR study on different transition metal phthalocyanines, elucidating the dependence of spin relaxation on solvent, ligand and metal ion. Coherence times of >40 µs and spin-lattice relaxation times of up to 2 s were found. Minimization of SOMO-environment overlap leads to increased coherence times.

The charge delocalization between the N-heterocyclic carbene (NHC) and the metal in cationic molybdenum imido alkylidene NHC mono(nonafluoro-tert-butoxide) complexes has been studied for different NHCs, i.e., 1,3-dimesitylimidazol-2ylidene (IMes), 1,3-dimesityl-4,5-dichloroimidazol-2-ylidene (IM-esCl 2 ), 1,3-dimesityl-4,5-dimethylimidazol-2-ylidene (IMesMe 2 ), and 1,3-dimesityl-4,5-dihydroimidazol-2-ylidene (IMesH 2 ). The binding situation in the corresponding cationic complexes Mo(N-2,6-Me 2 C 6 H 3 )(CHCMe 2 Ph)(NHC)(OC(CF 3 ) 3 ) + B(Ar F ) 4 − (NHC = IMes (1), IMesCl 2 (2), IMesMe 2 (3), and IMesH 2 (4) was compared to that of the analogous neutral Schrock catalyst Mo(N-2,6-Me 2 C 6 H 3 )(CHCMe 2 Ph)((OC(CF 3 ) 3 )) 2 (5). Singlecrystal X-ray data were used as a starting point for the optimization of the geometries of the catalysts at the PBE0-D3BJ/def2-SVP level of theory; the obtained data were compared to those obtained from X-ray absorption (XAS) and emission spectroscopy (XES). The very similar X-ray spectroscopic signatures of the XANES (X-ray absorption near-edge structure) and Kβ-XES of catalysts 1, 2, and 5 suggest that a similar oxidation state and charge are present at the Mo center in all three cases. However, charge delocalization is more pronounced in 1 and 2 compared to 5. This is supported by quantum chemical (QC) calculations, which reveal that all NHCs compensate to a very similar extent for the cationic charge at molybdenum, leading to charge model 5 (CM5) partial charges at Mo between +1.292 and +1.298. Accordingly, the partial charge in the NHCs was in the range of +0.486 to +0.515. This strong delocalization of the positive charge in cationic molybdenum imido alkylidene NHC (nonafluoro-tert-butoxide) complexes is also illustrated by the finding that the analogous neutral Schrock catalyst 5 has a more positive charge at molybdenum (+1.435) despite being a neutral 14-electron complex. Complementarily, charge analysis on complexes 1 and 2 and the acetonitrilecontaining derivatives 1•MeCN and 2•MeCN revealed that a small partial positive charge of about +0.1 was found on acetonitrile, accompanied by an increase in positive charge on Mo. Accordingly, the partial charges at the imido, the alkoxide, and NHC ligands decreased slightly. Finally, the catalytic activity of complexes 1−4 was determined for a number of purely hydrocarbon-based substrates in a set of olefin metathesis reactions. A correlation of the Tolman electronic parameter (TEP) with catalyst activity, expressed as the turnover frequency after 3 min, TOF 3min , was found for complexes 1−3 based on imidazol-2-ylidenes. 57 Fe-Mossbauer measurements on Mo(N-2,6-Me 2 C 6 H 3 )(CH-ferrocenyl)(NHC)(OTf) 2 and Mo(N-2,6-Me 2 C 6 H 3 )(CH-ferrocenyl)-(NHC)(OTf) + B(Ar F ) 4− (NHC = IMes (6, 8) and IMesH 2 (7, 9)) revealed significant changes in the quadrupole splitting of these complexes. These suggest a significantly more efficient charge distribution between the cationic molybdenum center and an imidazol-2-ylidene-based NHC compared t...

Nanoparticulate mackinawite was synthesized from elemental iron and sulfur in a convenient and reliable reaction. The structure and composition of the products were characterized and a new model describing the particle characteristics is established.

In this work, three different tochilinite‐like materials have been obtained by sophisticated synthetic methods that allow to control the distribution of iron ions. The purity of the samples was confirmed by powder X‐ray diffraction. From elemental analysis and Mössbauer spectroscopy data, detailed compositions could be determined: T1) Fe0.76S*0.86 [Fe2+0.01Fe3+0.56Mg2+0.43(OH)2.01]; T2) Fe0.89S*0.85 [Fe2+0.55Fe3+0.11Al3+0.33(OH)1.84(O)0.16]; T3) Fe0.71S*0.79 [Fe2+0.25Fe3+0.73Mg2+0.01Al3+0.01(OH)1.98(O)0.02]. These compositions fit to typical compositions of tochilinite in regard of the amount of iron vacancies and the volume ratio of the hydroxide layers to the sulfide layers. Besides hydroxide ions, oxide ions are also present in the hydroxide layers as a result of surface oxidation after the synthesis due to the high reactivity of the particles. TEM and SEM investigations show that the obtained powders consist mainly of thin sheets accompanied by nanotubes with BET surface areas ranging between 20 m2/g and 40 m2/g. The thermal stability was investigated by TGA and DSC analysis and it depends significantly on the composition.