Spin‐State‐Controlled Photodissociation of Iron(III) Azide to an Iron(V) Nitride Complex

Abstract

The generation of iron(V) nitride complexes, which are targets of biomimetic chemistry, is reported. Temperature-dependent ion spectroscopy shows that this reaction is governed by the spin-state population of their iron(III) azide precursors and can be tuned by temperature. The complex [(MePy TACN)Fe(N )] (MePy TACN=N-methyl-N,N-bis(2-picolyl)-1,4,7-triazacyclononane) exists as a mixture of sextet and doublet spin states at 300 K, whereas only the doublet state is populated at 3 K. Photofragmentation of the sextet state complex leads to the reduction of the iron center. The doublet state complex photodissociates to the desired iron(V) nitride complex. To generalize these findings, we show results for complexes with cyclam-based ligands.

Electron Paramagnetic Resonance Signature of Tetragonal Low Spin Iron(V)-Nitrido and -Oxo Complexes Derived from the Electronic Structure Analysis of Heme and Non-Heme Archetypes

“…Clearly, our findings show that low spin state of the ferric azido precursors is not the prerequisite for the photochemical generation of iron(V)-nitrido species. 43…”

Detection of Indistinct Fe−N Stretching Bands in Iron(V) Nitrides by Photodissociation Spectroscopy

“…[18][19][20][21][22][23] The generation of such reactive ions in the gas phase at low pressures precludes any unwanted bimolecular reactions, which usually hamper the investigation of these compounds in the condensed phase.…”

“…The studied complexes were prepared from their iron(III) azide precursors by nitrogen elimination during the electrospray ionization (ESI) process, as previously reported . The generation of such reactive ions in the gas phase at low pressures precludes any unwanted bimolecular reactions, which usually hamper the investigation of these compounds in the condensed phase.…”

The Electron Spin as a Chiral Reagent

“…[10] Electron spin, the intrinsic angular momentum of the electron, is an essential concept for describing the formation or breaking of chemical bonds in chemical reactions.Despite its importance,the control of chemical reactions by control of the electron-spin orientation has typically been limited to unimolecular or photochemical processes. [13,14] In part, this results from the electron spin not being strongly coupled or "locked" to the molecular frame,s ot hat the relative orientation of the spins of the reaction partners is not well defined. Therecently discovered effect of chiral-induced spin selectivity (CISS) in which an electron moving through ac hiral molecule is spin-polarized either parallel or antiparallel to its velocity [15,16] provides am echanism by which the electron spin can be fixed to amolecular symmetry axis.CISS implies that electrons can be extracted (or injected) from chiral molecules with apreferred spin orientation.…”

“…Electron spin, the intrinsic angular momentum of the electron, is an essential concept for describing the formation or breaking of chemical bonds in chemical reactions. Despite its importance, the control of chemical reactions by control of the electron‐spin orientation has typically been limited to unimolecular or photochemical processes . In part, this results from the electron spin not being strongly coupled or “locked” to the molecular frame, so that the relative orientation of the spins of the reaction partners is not well defined.…”