Solvent and Ligand Effects on the Structures of Iron Halide Cations in the Gas Phase

Abstract

The effects of the oxidation state, the ligand, and the solvent on structures and energetics of cationic iron complexes are investigated by means of electrospray‐ionization mass spectrometry. Insights into the potential‐energy surfaces of FeX+, FeX2+, and XFe(OCH3)+ ions (X = F, Cl, Br, I) with a variable number of coordinated methanol molecules are obtained by means of collision experiments and complementary thermochemical considerations. It is shown that upon change of the halide ligand, the weakly solvated ions respond differentially to the increasing need for stabilization of the partial charge on the metal center. For example, whereas F2Fe(CH3OH)n+ ions tend to lose mainly HF for n = 1–3, the loss of HBr is not observed at all for Br2Fe(CH3OH)n+. Instead, the iron‐bromide cations undergo reductive loss of atomic bromine. Cl2Fe(CH3OH)n+ bears an intermediate position in that both reduction as well as elimination of HCl can occur. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)

Generation and Reactivity of Enantiomeric (BINOLato)Ni+ Complexes with Chiral Secondary Alcohols in the Gas Phase

“…Energy behavior of such a kind is mechanistically significant because it implies that the elimination of acetophenone is kinetically hindered, whereas the loss of the alcohol is a simple, continuously endothermic process. [30] In the competition between these two processes at variable collision energies, the ketone elimination occurs first-that is, at lower collision energy than the loss of the alcohol-but has to pass through a rate-determining transition structure associated with bond activation. In contrast, once a sufficient amount of energy for the direct loss of the alcohol ligand is available in CID, this barrier-free reaction can occur and predominates over the kinetically controlled ketone formation at larger collision energies.…”

Clustering of palladium(II) chloride in acetonitrile solution investigated by electrospray mass spectrometry

“…At the outset we note that the ESI mass spectra of PdCl 2 solutions in acetonitrile are much poorer in absolute ion abundances than the typical ESI mass spectra of metal(II) chlorides in protic solvents [22,28,43] and also than the ESI mass spectra of palladium(0) or palladium(II) complexes with larger organic ligands [44]. This general observation may be regarded as an indication that the heterolysis of PdCl 2 solutions in acetonitrile according to reaction (1) is poor and/or that palladium chloride shows a large tendency for aggregation to clusters in acetonitrile solution.…”

Studies of gas‐phase reactions of cationic iron complexes of 2‐pyrimidinyloxy‐N‐arylbenzylamines by electrospray ionization tandem mass spectrometry

“…The gas‐phase SET reactions implied that a similar SET process might also occur in the solution phase, giving rise to the 1 – 6 · Fe(II)Cl + in the mixed solution of 1 – 6 with FeCl 3 . However, the most widely accepted mechanism of forming Fe(II) complex ions in FeCl 3 solution of 1 – 6 still is the in‐source reduction process during analysis of transition‐metal complexes in the ESI process 35–37…”

“…However, the most widely accepted mechanism of forming Fe(II) complex ions in FeCl 3 solution of 1-6 still is the in-source reduction process during analysis of transition-metal complexes in the ESI process. [35][36][37] Obtaining 1-6 Á Fe(II)X R (X ¼ Cl, Br) with the micro-reactor device coupled to ESI Then, we mixed 1 equiv. of the methanolic solution of compounds 1-6 with 1 equiv.…”