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Title: Spectroscopic and Computational Studies of Spin States of Iron(IV) Nitrido and Imido Complexes

Abstract

High-oxidation state metal complexes with multiply bonded ligands are of great interest for both their reactivity as well as their fundamental bonding properties. This paper reports a combined spectroscopic and theoretical investigation into the effect of the apical multiply bonded ligand on the spin state preferences of three-fold symmetric iron(IV) complexes with tris(carbene) donor ligands. Specifically, singlet (S = 0) nitrido [{PhB(Im R) 3}FeN], R = tBu (1), Mes (mesityl, 2) and the related triplet (S = 1) imido complexes, [{PhB(Im R) 3}Fe(NR')] +, R = Mes, R' = Ad (1- adamantyl, 3), tBu (4), have been investigated by electronic absorption and Mössbauer effect spectroscopies. For comparison, two other Fe(IV) nitrido complexes, [(TIMEN Ar)FeN] +, (TIMEN Ar = tris[2-(3-aryl-imidazol-2-ylidene)ethyl]amine; Ar = Xyl (xylyl), Mes), have been investigated by 57Fe Mössbauer spectroscopy, including applied-field measurements. The paramagnetic imido complexes 3 and 4 were also studied by magnetic susceptibility measurements (for 3) and paramagnetic resonance spectroscopy: high-frequency and -field electron paramagnetic resonance (HFEPR) (for 3 and 4) and frequency-domain Fouriertransform (FD-FT) THz EPR (for 3), which reveal their zero-field splitting (zfs) parameters. Experimentally correlated theoretical studies comprising ligand-field theory (LFT) and quantum chemical theory (QCT), the latter including both density functional theorymore » (DFT) and ab initio methods reveal the key role played by the Fe3 d z2 (a1) orbital in these systems: the nature of its interaction with the nitrido or imido ligand dictates the spin state preference of the complex. Lastly, the ability to tune the spin state through the energy and nature of a single orbital has general relevance to the factors controlling spin states in complexes with applicability as single molecule devices.« less

Authors:
; ; ; ; ORCiD logo; ; ; ORCiD logo; ORCiD logo; ; ORCiD logo; ; ; ; ; ORCiD logo; ORCiD logo
Publication Date:
Research Org.:
Indiana Univ., Bloomington, IN (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1348217
Grant/Contract Number:
FG02-08ER15996; CHE04-43580; DMR-1351959; DMR 1157490; NE 2064/1-1 FOR
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Inorganic Chemistry
Additional Journal Information:
Journal Volume: 56; Journal Issue: 8; Journal ID: ISSN 0020-1669
Publisher:
American Chemical Society (ACS)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY

Citation Formats

Bucinsky, Lukas, Breza, Martin, Lee, Wei-Tsung, Hickey, Anne K., Dickie, Diane A., Nieto, Ismael, DeGayner, Jordan A., Harris, T. David, Meyer, Karsten, Krzystek, J., Ozarowski, Andrew, Nehrkorn, Joscha, Schnegg, Alexander, Holldack, Karsten, Herber, Rolfe H., Telser, Joshua, and Smith, Jeremy M. Spectroscopic and Computational Studies of Spin States of Iron(IV) Nitrido and Imido Complexes. United States: N. p., 2017. Web. doi:10.1021/acs.inorgchem.7b00512.
Bucinsky, Lukas, Breza, Martin, Lee, Wei-Tsung, Hickey, Anne K., Dickie, Diane A., Nieto, Ismael, DeGayner, Jordan A., Harris, T. David, Meyer, Karsten, Krzystek, J., Ozarowski, Andrew, Nehrkorn, Joscha, Schnegg, Alexander, Holldack, Karsten, Herber, Rolfe H., Telser, Joshua, & Smith, Jeremy M. Spectroscopic and Computational Studies of Spin States of Iron(IV) Nitrido and Imido Complexes. United States. doi:10.1021/acs.inorgchem.7b00512.
Bucinsky, Lukas, Breza, Martin, Lee, Wei-Tsung, Hickey, Anne K., Dickie, Diane A., Nieto, Ismael, DeGayner, Jordan A., Harris, T. David, Meyer, Karsten, Krzystek, J., Ozarowski, Andrew, Nehrkorn, Joscha, Schnegg, Alexander, Holldack, Karsten, Herber, Rolfe H., Telser, Joshua, and Smith, Jeremy M. Wed . "Spectroscopic and Computational Studies of Spin States of Iron(IV) Nitrido and Imido Complexes". United States. doi:10.1021/acs.inorgchem.7b00512. https://www.osti.gov/servlets/purl/1348217.
@article{osti_1348217,
title = {Spectroscopic and Computational Studies of Spin States of Iron(IV) Nitrido and Imido Complexes},
author = {Bucinsky, Lukas and Breza, Martin and Lee, Wei-Tsung and Hickey, Anne K. and Dickie, Diane A. and Nieto, Ismael and DeGayner, Jordan A. and Harris, T. David and Meyer, Karsten and Krzystek, J. and Ozarowski, Andrew and Nehrkorn, Joscha and Schnegg, Alexander and Holldack, Karsten and Herber, Rolfe H. and Telser, Joshua and Smith, Jeremy M.},
abstractNote = {High-oxidation state metal complexes with multiply bonded ligands are of great interest for both their reactivity as well as their fundamental bonding properties. This paper reports a combined spectroscopic and theoretical investigation into the effect of the apical multiply bonded ligand on the spin state preferences of three-fold symmetric iron(IV) complexes with tris(carbene) donor ligands. Specifically, singlet (S = 0) nitrido [{PhB(ImR)3}FeN], R = tBu (1), Mes (mesityl, 2) and the related triplet (S = 1) imido complexes, [{PhB(ImR)3}Fe(NR')]+, R = Mes, R' = Ad (1- adamantyl, 3), tBu (4), have been investigated by electronic absorption and Mössbauer effect spectroscopies. For comparison, two other Fe(IV) nitrido complexes, [(TIMENAr)FeN]+, (TIMENAr = tris[2-(3-aryl-imidazol-2-ylidene)ethyl]amine; Ar = Xyl (xylyl), Mes), have been investigated by 57Fe Mössbauer spectroscopy, including applied-field measurements. The paramagnetic imido complexes 3 and 4 were also studied by magnetic susceptibility measurements (for 3) and paramagnetic resonance spectroscopy: high-frequency and -field electron paramagnetic resonance (HFEPR) (for 3 and 4) and frequency-domain Fouriertransform (FD-FT) THz EPR (for 3), which reveal their zero-field splitting (zfs) parameters. Experimentally correlated theoretical studies comprising ligand-field theory (LFT) and quantum chemical theory (QCT), the latter including both density functional theory (DFT) and ab initio methods reveal the key role played by the Fe3dz2 (a1) orbital in these systems: the nature of its interaction with the nitrido or imido ligand dictates the spin state preference of the complex. Lastly, the ability to tune the spin state through the energy and nature of a single orbital has general relevance to the factors controlling spin states in complexes with applicability as single molecule devices.},
doi = {10.1021/acs.inorgchem.7b00512},
journal = {Inorganic Chemistry},
number = 8,
volume = 56,
place = {United States},
year = {Wed Apr 05 00:00:00 EDT 2017},
month = {Wed Apr 05 00:00:00 EDT 2017}
}

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  • Most transition metal imido (or nitrene) complexes are nucleophilic at nitrogen, but certain species exhibit reactivity patterns indicative of electrophilic character. For example, high-valent manganese(V) and iron(V) derivatives, activated by trifluoroacetyl and tosyl groups, respectively, transfer the nitrene unit to alkenes to produce aziridines. McElwee-White et al. have reported that the putative (CO){sub 5}W{double_bond}NC{sub 6}H{sub 5} complex can behave as a nucleophile or an electrophile; the latter property is illustrated by reaction with PPh{sub 3} to form PhNPPh{sub 3}. Our work has focused on preparing low-valent metal nitrene complexes containing strong {pi}-acid ligands in the coordination sphere, features which maymore » impart electrophilic character to nitrogen. This communication describes the simple amido (NH{sub 2}{sup -}), imido (NH{sup 2-}), and nitrido (N{sup 3-}) derivatives of the low-valent tungsten moiety Tp{prime}(CO){sub 2}W(Tp{prime} = hydrotris(3,5-dimethyl-1-pyrazolyl)borate) and their facile interconversions. The nitrode complex serves as a convenient precursor to a variety of cationic nitrene complexes. 15 refs., 2 figs.« less
  • The nitrido-bridged osmium(IV) binuclear complexes (Os{sub 2}N(NH{sub 3}){sub 8}Cl{sub 2})Cl{sub 3} {times} 2H{sub 2}O (I) and (Os{sub 2}N(NH{sub 3}){sub 7}Cl{sub 3})Cl{sub 2} {times} H{sub 2}O (II) have been shown to be products of the ammonolysis of sodium hexachloroosmate(IV) (Na{sub 2}(OsCl{sub 6})) in aqueous ammonia at elevated temperatures. Spectral (infrared and uv-vis) and electrochemical properties of the complexes have been explored. In aqueous solution, I and II undergo aquation reactions involving the chloro ligands, and the resulting aqua complexes of I and II exhibit respectively two and three ionizable protons with pK{sub a} values in the range 3.6-7.3. In purified form,more » the complexes I and II plus their aquated derivatives were found to be ineffective as DNA-selective, electron-dense stains for electron microscopy, whereas effective staining was observed with unpurified mixtures. 26 refs., 1 fig., 1 tab.« less
  • In this paper, we report the synthesis, reactivity, and structural properties of the d{sup 0} W(=NR){sub 3} functional group, describe experiments that address how multiple imido complexes arise, and demonstrate an electronic analogy of W(=NR){sub 3} to related M(l{rho},2{pi}){sub 3} complexes. 41 refs., 3 figs., 4 tabs.
  • Bis(N-methylethylenediaminesalicylaldiminato)iron(III) complexes, (Fe(X-Salmeen)/sub 2/)(PF/sub 6/), with their FeN/sub 4/O/sub 2/ cores have been shown by variable-temperature magnetic susceptibility (10 to 300 K) and Moessbauer spectroscopy to be new (low-spin, S = /sup 1///sub 2/) reversible (high-spin, S = /sup 5///sub 2/), spin-squilibrium compounds in the solid state. From the Moessbauer spectra, an upper limit of approximately 10/sup 7/s/sup -1/ has been established for the rate of intersystem crossing in the solid state. The spin equilibria are also supported in the solution state, as verified by variable-temperature (200 to 300 K) magnetic susceptibility and electronic spectroscopy measurements. In solution, laser Ramanmore » temperature-jump kinetics has been employed to directly measure the forward (k/sub 1/) and reverse (k/sub -1/) rate constants for the intersystem crossings with 2 x 10/sup 7/s/sup -1/ < or approximately k < or approximately 2 x 10/sup 8/s/sup -1/. Intersystem crossing rate constant data for these bis-tridentate (Fe/sup III/(X-Salmeen)/sub 2/)/sup +/ complexes are discussed and compared to data already available for the electronically similar (same FeN/sub 4/O/sub 2/ core) but structurally different (hexadentate ligand) spin-equilibrium species, (Fe/sup III/(Sal)/sub 2/trien)/sup +/. 4 tables, 6 figures, 40 references.« less