π-Lewis Base Activation of Carbonyls and Hexafluorobenzene.

We report hitherto elusive side-on η-bonded palladium(0) carbonyl (anthraquinone, benzaldehyde) and arene (benzene, hexafluorobenzene) palladium(0) complexes and present the catalytic hydrodefluorination of hexafluorobenzene by cyclohexene. The comparison with respective cyclohexene, pyridine and tetrahydrofuran complexes reveals that the experimental ligand binding strengths follow the order THF View Article and Find Full Text PDF

Reinvestigation of the mechanism of dioxygen activation at a Mn(cyclam) center.

This study deals with the unprecedented reactivity of a [(cyclam)Mn(OTf)] (3-cis; OTf = CFSO) with O, which, depending on the presence or absence of a hydrogen atom donor like 1-hydroxy-2,2,6,6-tetramethyl-piperidine (TEMPO-H), selectively generates di-μ-oxo Mn(III)Mn(IV) (1) or Mn (2) complexes, respectively. Both dimers have been characterized by different techniques including single-crystal X-ray diffraction, X-ray absorption spectroscopy, and electron paramagnetic resonance. Oxygenation reactions carried out with labeled O and Resonance Raman spectroscopy unambiguously show that the oxygen atoms present in the MnMn dimer originate from O.

A bis-Phenolate Carbene-Supported bis-μ-Oxo Iron(IV/IV) Complex with a [Fe(μ-O)Fe] Diamond Core Derived from Dioxygen Activation.

The diiron(II) complex, [(OCO)Fe(MeCN)] (, MeCN = acetonitrile), supported by the bis-phenolate carbene pincer ligand, 1,3-bis(3,5-di--butyl-2-hydroxyphenyl)benzimidazolin-2-ylidene (OCO), was synthesized and characterized by single-crystal X-ray diffraction, H nuclear magnetic resonance, infrared (IR) vibrational, ultraviolet/visible/near-infrared (UV/vis/NIR) electronic absorption, Fe Mössbauer, X-band electron paramagnetic resonance (EPR) and SQUID magnetization measurements. Complex activates dioxygen to yield the diferric, μ-oxo-bridged complex [(OCO)Fe(py)(μ-O)Fe(O(C═O)O)(py)] () that was isolated and fully characterized. In , one of the iron-carbene bonds was oxidized to give a urea motif, resulting in an O(C═O)O binding site, while the other Fe(OCO) unit remained unchanged.

A Bioinspired Nonheme Fe-(O)-Cu Complex with an = 1 Ground State.

Cytochrome oxidase (CcO) is a heme copper oxidase (HCO) that catalyzes the natural reduction of oxygen to water. A profound understanding of some of the elementary steps leading to the intricate 4e/4H reduction of O is presently lacking. A total spin = 1 Fe-(O)-Cu () intermediate is proposed to reduce the overpotentials associated with the reductive O-O bond rupture by allowing electron transfer from a tyrosine moiety without the necessity of any spin-surface crossing.