Intermediate-spin iron(iv)-oxido species with record reactivity

Abstract

The nonheme iron(IV)-oxido complex trans-N3-[(L1)FeIV=O(Cl)]+, where L1 is a derivative of the tetradentate bispidine 2,4-di(pyridine-2-yl)-3,7-diazabicyclo[3.3.1]nonane-1-one, has an S = 1 electronic ground state and is the most reactive nonheme iron...

The π-interactions of ammonia ligands evaluated byab initioligand field theory

“…This assumption was also made for other complexes. [6][7][8][9][10][11][12]40 CASSCF/NEVPT2 calculations on the [Cu(NH 3 ) 5 ] 2+ subunit from the crystal structure yield an orbital ordering and d-d transitions in very good agreement with the measured ones, see Table 1. We note that while spin-orbit coupling (SOC) may be of importance for copper complexes (single-electron SOC parameter of ca.…”

“…In coordination chemistry, it is frequently assumed that the interaction between a metal centre and an ammonia ligand is characterised exclusively by σ character and thus that any π character is negligible. [1][2][3][4][5][6][7][8][9][10][11][12] This can be rationalized in an orbital picture: ammonia does not have any molecular orbitals of π character; only the σ /σ * molecular orbitals of the N−H bonds are partly oriented such that the metal-ammonia binding axis can lie in the nodal plane of a metal d orbital. Ammonia is therefore commonly classified as a σ -only ligand.…”

Natural Abiotic Iron-Oxido-Mediated Formation of C1 and C2 Compounds from Environmentally Important Methyl-Substituted Substrates

“…This is further supported by experiments, where either CH 2 Br 2 or CCl 3 Br was added to the standard experiment (see the Supporting Information for experimental conditions and detailed results, Figure S11): both CH 2 Br 2 and CCl 3 Br are known to trap alkyl radicals and lead to the corresponding brominated products, i.e., CD 3 Br in our experiments with d 6 -DMSO, and the resulting products of the quencher; i.e., CH 2 Br and CCl 3 radicals abstract H (or D) atoms from the molecules present in solution to produce CH 3 Br (or CH 2 DBr) and CHCl 3 (or CDCl 3 ), respectively. 35,52,53 As for the CD 3 radicals produced from d 6 -DMSO, a range of C 1 and C 2 products are expected from CH 2 Br and CCl 3 radicals with CH 3 Br and CHCl 3 as the main products. Unfortunately, the solubility of the two quenchers in aqueous solution is limited.…”

ESI and tandem MS for mechanistic studies with high-valent transition metal species

“…Together with product analyses and tandem ESI-MS (see below), spectroscopic data of trapped intermediates and computational work, in the case of the tetradentate bispidine system this led to a consistent interpretation of the mechanistic pathways and the theoretical basis for the unprecedented reactivity. 66,85,92 However, as general in mechanistic work, one needs to be cautious with interpretations. The current analysis assigns the iron(III) species observed in the ESI-MS experiments with a 1 u reduced mass as a rebound intermediate on the intramolecular decay pathway of the reactive ferryl intermediate (see Fig.…”

“…90,91 This ferryl complex is indeed the most reactive nonheme iron( iv )-oxido compound known so far: it decays at −90 °C in seconds. 89,92 The ESI-MS experiments described above were able to unambiguously define the stoichiometries of important intermediates on the pathways of decay of this interesting oxidant, and these could therefore produce images of the history of the corresponding initial species, i.e. of the elusive ferryl precursor, for which only optical spectra observed in cryo-stopped flow experiments 66,84,87 and so far unpublished additional spectroscopic data of freeze-quenched samples exist.…”