Electron spin adjustment in manganocenes. Preparative, paramagnetic NMR and X-ray study on substituent and solvent effects

Supramolecular Catalysis of Orthoformate Hydrolysis in Basic Solution: An Enzyme-Like Mechanism

“…The melting behavior is rather interesting since the melting points increase in the order (Me 3 E)C 5 H 4 < (Me 3 E) 2 2 Mn are determined at low temperature (see Table 2 for details), while that of [(Me 3 Si)C 5 H 4 ] 2 Mn was reported some years ago. 19 Thus, the solid state structures of the manganocenes described in this paper are known, except for the mixed-ring metallocene [(Me 3 C)(Me 3 Si)C 5 H 3 ] 2 Mn; several attempts to grow suitable crystals for an X-ray diffraction study either by slow sublimation or crystallization failed. The ORTEP diagrams are given in [(Me 3 C)C 5 H 4 ] 2 Mn has C 2h symmetry, the rings are staggered, and the CMe 3 groups point away from each other to reduce intramolecular interactions.…”

Fluxional Processes in Diamagnetic and Paramagnetic Allyl Dicarbonyl and 2-Methylallyl Dicarbonyl Molybdenum Histidinato Complexes as Revealed by Spectroscopic Data and Density Functional Calculations

“…The coordination sphere around the Mo atoms in 1, 3, and 4 consists of identical donor atoms, namely two carbonyl ligands, three carbon atoms from an allyl (1) or 2-Me-allyl (3 and 4) ligand and the carboxylato oxygen atom, amine nitrogen atom, and nitrogen atom N d of either a histidine (1 and 3) or N e -substituted histidine (4). The Mo(allyl)(CO) 2 (1) and Mo(2-Me-allyl)(CO) 2 (3 and 4) moieties are in a facial arrangement with the terminal CH 2 carbon atoms of the allyl or 2-Me-allyl ligand oriented towards the carbonyl ligands.…”

“…The high-spin state of manganocene derivatives is readily accessible and has been studied in detail. [3,4] Maximum spin Cp (Cp h-cyclopentadienyl) complexes of the 3d transition metals in general have been reviewed recently by Sitzmann. [5] The work on paramagnetic Cr compounds, including some very interesting hydrides, has been pioneered by Theopold and Jolly.…”

Solid-State NMR Spectroscopy of Paramagnetic Metallocenes

“…The associated spinning sideband manifolds cover ranges of about 1100 and 600 ppm, respectively. Based on comparison with solution-state proton NMR spectra of mono-and dinuclear high-spin manganocene (46,47) the signals at −13 and 125 ppm must be assigned to the protons of the terminal and bridging ligand, respectively. Since only one signal was found for the di-and trihapto moiety of the bridging ligand, it must be concluded that rapid haptotropic rearrangement occurs.…”