Reassessment of N2 activation by low-valent Ti-amide complexes: a remarkable side-on bridged bis-N2 adduct is actually an arene adduct

Daniel N. Huh; Ross F. Koby; Zoe E. Stuart; Rachel J. Dunscomb; Nathan D. Schley; Ian A. Tonks

doi:10.1039/d2sc04368h

Reassessment of N₂ activation by low-valent Ti-amide complexes: a remarkable side-on bridged bis-N₂ adduct is actually an arene adduct

Daniel N. Huh, Ross F. Koby, Zoe E. Stuart, Rachel J. Dunscomb, Nathan D. Schley, Ian A. Tonks

Chemistry (Twin Cities)

Research output: Contribution to journal › Article › peer-review

3 Scopus citations

Abstract

The complex {(TMEDA)₂Li}{[Ti(N(TMS)₂)₂]₂(μ-η²:η²-N₂)₂} (5-Li) is the only transition metal N₂ complex ever reported with two side-on N₂ adducts. In this report, the similarity of 5-Li to a new inverse sandwich toluene adduct {(PhMe)K}{[Ti(N(TMS)₂)₂]₂(μ-PhMe)} (6-K) necessitated a re-examination of the structure of 5-Li. Through a reassessment of the original disordered crystal data of 5-Li and new independent syntheses brought about through revisitation of the original reaction conditions, 5-Li has been re-assigned as an inverse sandwich toluene adduct, {(TMEDA)₂Li}{[Ti(N(TMS)₂)₂]₂(μ-PhMe)} (6-Li). The original crystal data could be fitted almost equally well to structural solutions as either 5-Li or 6-Li, and this study highlights the importance of a holistic examination of modeled data and the need for secondary/complementary analytical methods in paramagnetic inorganic syntheses, especially when presenting unique and unexpected results. In addition, further examination of reduction reactions of Ti[N(TMS)₂]₃ and [(TMS)₂N]₂TiCl(THF) in the presence of KC₈ revealed rich solvent- and counterion-dependent chemistry, including several degrees of N₂ activation (bridging nitride complexes, terminal bridging N₂ complexes) as well as ligand C-H activation.

Original language	English (US)
Pages (from-to)	13330-13337
Number of pages	8
Journal	Chemical Science
Volume	13
Issue number	45
DOIs	https://doi.org/10.1039/d2sc04368h
State	Published - Oct 14 2022

Bibliographical note

Funding Information:
Financial support was provided by the National Institutes of Health (R35GM119457). Additional support was provided by the National Institute of General Medicine Sciences of the National Institutes of Health to D. N. H. from the Ruth L. Kirschstein NRSA Postdoctoral Fellowship (F32GM137547). Instrumentation for the University of Minnesota Chemistry NMR facility was supported from a grant through the National Institutes of Health (S10OD011952). X-ray diffraction experiments were performed with a diffractometer purchased through a grant from NSF/MRI (1229400) and the University of Minnesota. We thank Dr Victor G. Young Jr and Margaret C. Clapham of the University of Minnesota X-ray Crystallographic Laboratory for their assistance with SC-XRD. We also thank Chase Abelson and Prof. Larry Que for assistance with UV-vis and Raman spectroscopy.

Publisher Copyright:
© 2022 The Royal Society of Chemistry.

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@article{a638cd5cbf5748ccb5580f8c573c8dfb,

title = "Reassessment of N2 activation by low-valent Ti-amide complexes: a remarkable side-on bridged bis-N2 adduct is actually an arene adduct",

abstract = "The complex {(TMEDA)2Li}{[Ti(N(TMS)2)2]2(μ-η2:η2-N2)2} (5-Li) is the only transition metal N2 complex ever reported with two side-on N2 adducts. In this report, the similarity of 5-Li to a new inverse sandwich toluene adduct {(PhMe)K}{[Ti(N(TMS)2)2]2(μ-PhMe)} (6-K) necessitated a re-examination of the structure of 5-Li. Through a reassessment of the original disordered crystal data of 5-Li and new independent syntheses brought about through revisitation of the original reaction conditions, 5-Li has been re-assigned as an inverse sandwich toluene adduct, {(TMEDA)2Li}{[Ti(N(TMS)2)2]2(μ-PhMe)} (6-Li). The original crystal data could be fitted almost equally well to structural solutions as either 5-Li or 6-Li, and this study highlights the importance of a holistic examination of modeled data and the need for secondary/complementary analytical methods in paramagnetic inorganic syntheses, especially when presenting unique and unexpected results. In addition, further examination of reduction reactions of Ti[N(TMS)2]3 and [(TMS)2N]2TiCl(THF) in the presence of KC8 revealed rich solvent- and counterion-dependent chemistry, including several degrees of N2 activation (bridging nitride complexes, terminal bridging N2 complexes) as well as ligand C-H activation.",

author = "Huh, {Daniel N.} and Koby, {Ross F.} and Stuart, {Zoe E.} and Dunscomb, {Rachel J.} and Schley, {Nathan D.} and Tonks, {Ian A.}",

note = "Funding Information: Financial support was provided by the National Institutes of Health (R35GM119457). Additional support was provided by the National Institute of General Medicine Sciences of the National Institutes of Health to D. N. H. from the Ruth L. Kirschstein NRSA Postdoctoral Fellowship (F32GM137547). Instrumentation for the University of Minnesota Chemistry NMR facility was supported from a grant through the National Institutes of Health (S10OD011952). X-ray diffraction experiments were performed with a diffractometer purchased through a grant from NSF/MRI (1229400) and the University of Minnesota. We thank Dr Victor G. Young Jr and Margaret C. Clapham of the University of Minnesota X-ray Crystallographic Laboratory for their assistance with SC-XRD. We also thank Chase Abelson and Prof. Larry Que for assistance with UV-vis and Raman spectroscopy. Publisher Copyright: {\textcopyright} 2022 The Royal Society of Chemistry.",

year = "2022",

month = oct,

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doi = "10.1039/d2sc04368h",

language = "English (US)",

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T1 - Reassessment of N2 activation by low-valent Ti-amide complexes

T2 - a remarkable side-on bridged bis-N2 adduct is actually an arene adduct

AU - Huh, Daniel N.

AU - Koby, Ross F.

AU - Stuart, Zoe E.

AU - Dunscomb, Rachel J.

AU - Schley, Nathan D.

AU - Tonks, Ian A.

N1 - Funding Information: Financial support was provided by the National Institutes of Health (R35GM119457). Additional support was provided by the National Institute of General Medicine Sciences of the National Institutes of Health to D. N. H. from the Ruth L. Kirschstein NRSA Postdoctoral Fellowship (F32GM137547). Instrumentation for the University of Minnesota Chemistry NMR facility was supported from a grant through the National Institutes of Health (S10OD011952). X-ray diffraction experiments were performed with a diffractometer purchased through a grant from NSF/MRI (1229400) and the University of Minnesota. We thank Dr Victor G. Young Jr and Margaret C. Clapham of the University of Minnesota X-ray Crystallographic Laboratory for their assistance with SC-XRD. We also thank Chase Abelson and Prof. Larry Que for assistance with UV-vis and Raman spectroscopy. Publisher Copyright: © 2022 The Royal Society of Chemistry.

PY - 2022/10/14

Y1 - 2022/10/14

N2 - The complex {(TMEDA)2Li}{[Ti(N(TMS)2)2]2(μ-η2:η2-N2)2} (5-Li) is the only transition metal N2 complex ever reported with two side-on N2 adducts. In this report, the similarity of 5-Li to a new inverse sandwich toluene adduct {(PhMe)K}{[Ti(N(TMS)2)2]2(μ-PhMe)} (6-K) necessitated a re-examination of the structure of 5-Li. Through a reassessment of the original disordered crystal data of 5-Li and new independent syntheses brought about through revisitation of the original reaction conditions, 5-Li has been re-assigned as an inverse sandwich toluene adduct, {(TMEDA)2Li}{[Ti(N(TMS)2)2]2(μ-PhMe)} (6-Li). The original crystal data could be fitted almost equally well to structural solutions as either 5-Li or 6-Li, and this study highlights the importance of a holistic examination of modeled data and the need for secondary/complementary analytical methods in paramagnetic inorganic syntheses, especially when presenting unique and unexpected results. In addition, further examination of reduction reactions of Ti[N(TMS)2]3 and [(TMS)2N]2TiCl(THF) in the presence of KC8 revealed rich solvent- and counterion-dependent chemistry, including several degrees of N2 activation (bridging nitride complexes, terminal bridging N2 complexes) as well as ligand C-H activation.

AB - The complex {(TMEDA)2Li}{[Ti(N(TMS)2)2]2(μ-η2:η2-N2)2} (5-Li) is the only transition metal N2 complex ever reported with two side-on N2 adducts. In this report, the similarity of 5-Li to a new inverse sandwich toluene adduct {(PhMe)K}{[Ti(N(TMS)2)2]2(μ-PhMe)} (6-K) necessitated a re-examination of the structure of 5-Li. Through a reassessment of the original disordered crystal data of 5-Li and new independent syntheses brought about through revisitation of the original reaction conditions, 5-Li has been re-assigned as an inverse sandwich toluene adduct, {(TMEDA)2Li}{[Ti(N(TMS)2)2]2(μ-PhMe)} (6-Li). The original crystal data could be fitted almost equally well to structural solutions as either 5-Li or 6-Li, and this study highlights the importance of a holistic examination of modeled data and the need for secondary/complementary analytical methods in paramagnetic inorganic syntheses, especially when presenting unique and unexpected results. In addition, further examination of reduction reactions of Ti[N(TMS)2]3 and [(TMS)2N]2TiCl(THF) in the presence of KC8 revealed rich solvent- and counterion-dependent chemistry, including several degrees of N2 activation (bridging nitride complexes, terminal bridging N2 complexes) as well as ligand C-H activation.

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