Multistate-Mediated Rearrangements and FeCl₂ Elimination in Dinuclear FePd Complexes

Abstract

Mass spectrometric, spectroscopic, and computational characterization of a novel bifunctional iron-palladium complex proves a change of coordination upon solvation. Collisional excitation reveals FeCl2 and HCl elimination in a solvent-modulated competition. Hereby, syn and anti isomers, identified by theoretical calculations, favor and disfavor FeCl2 elimination, respectively. The FeCl2 elimination likely proceeds by chlorido and Cp ligand exchange among the metallic centers in a concerted, ballet-like manner. A multitude of stationary points were identified along the computed multistep reaction coordinates of the three conceivable spin states. The quintet state shows a static Jahn-Teller type relaxation by a tilt away of the Cp ligand at the iron center. The direct singlet-quintet spin crossover is an unprecedented assumption, leaving behind the triplet state as a spectator without involvement. The FeCl2 elimination would decrease catalytic activity. It is kinetically hindered within a range of applicable temperatures in conceivable technical applications.

Cryo Kinetics and Spectroscopy of Cationic Nickel Clusters: Rough and Smooth Surfaces

“…We have been preparing ionic TM clusters within ion traps, e.g., for kinetic studies of hydrocarbon activation, and we have introduced X-ray studies by cryo ion trapping for the investigation of spin and orbital contributions to the magnetic moments of TM clusters. , In parallel, we have utilized table top IR lasers for the identification of dark IR-MPD bands in oligonuclear TM complexes, torsional isomerizations, and multistate-mediated rearrangements . Recently, we have upgraded our instrumentation toward tandem cryo ion trapping, and we have started a long-term quest for the vibrational spectroscopy of N 2 adsorbates on size selected TM clusters under isothermal cryo conditions, first results on [Co n (N 2 ) 1 ] + clusters and on Fe based “non-classical” dinitrogen complexes being published. , This study aims to elucidate N 2 adsorption onto cationic nickel clusters, [Ni n (N 2 ) m ] + , by a combination of kinetic investigations, IR-PD spectroscopy, and DFT based modeling of structures and vibrations.…”

Intermetallic Competition in the Fragmentation of Trimetallic Au–Zn–Alkali Complexes

“…Standard Gibbs energies of structures, Δ G 0 , and of fragmentation pathways, Δ frag G 0 , also known as free enthalpies, were calculated at 300 K. Harmonic vibrational frequencies were scaled with 0.955 (0.975) above (below) 2000 cm −1 to match the most intense experimental bands (e.g., at 3374 cm −1 for [AuZnCl 3 Li] + ). We checked for triplet and quintet states and found those to be at least 100 kJ mol −1 less stable and thus of no relevance in the present context—in remarkable contrast to the CID of a Fe–Pd complex, which revealed a direct singlet to quintet crossover …”

“…We checked for triplet and quintet states and found those to be at least 100 kJ mol À1 less stable and thus of no relevance in the present context-inr emarkable contrast to the CID of aF e-Pd complex, which revealed ad irect singlet to quintet crossover. [29] Infrared absorption spectrao fp owder samples were measured with an attenuated total reflection (ATR) spectrometer (PerkinElmer Spectrum 100 FT-IR with au niversal ATRs ampling accessory). Background spectra were subtracted fromt he sample spectrumf or background correction.…”

Advancing Inorganic Coordination Chemistry by Spectroscopy of Isolated Molecules: Methods and Applications

“…Then it becomes possible not only to study the kinetics of solution reactions by using ESI-MS to probe reactant and product concentrations [11] but also to study the mechanism by resolving charged intermediates, for example in selected homogeneously catalysed reactions. [12][13][14][15][16] ESI-IMS-MS and ESI-MS-IMS-MS: Ion mobility mass spectrometry (IMS-MS) as applied to the structural characterization of molecular ions dates back to the early 1990's. [17] In its first and conceptually simplest "drift-tube" variant, a DC electric field pulls ions through a collision cell containing an inert collision gas such as helium or nitrogen (at a pressure of a few mbar).…”

“…Then it becomes possible not only to study the kinetics of solution reactions by using ESI‐MS to probe reactant and product concentrations [11] but also to study the mechanism by resolving charged intermediates, for example in selected homogeneously catalysed reactions. [ 12 , 13 , 14 , 15 , 16 ]…”