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Title: Molecular titanium nitrides: nucleophiles unleashed

Abstract

In this contribution we present reactivity studies of a rare example of a titanium salt, in the form of [μ 2-K(OEt 2)] 2[(PN) 2Ti$$\equiv$$N] 2 (1) (PN - = N-(2-(diisopropylphosphino)-4-methylphenyl)-2,4,6-trimethylanilide) to produce a series of imide moieties including rare examples such as methylimido, borylimido, phosphonylimido, and a parent imido. For the latter, using various weak acids allowed us to narrow the pK a range of the NH group in (PN) 2Ti$$\equiv$$NH to be between 26–36. Complex 1 could be produced by a reductively promoted elimination of N 2 from the azide precursor (PN) 2TiN 3, whereas reductive splitting of N 2 could not be achieved using the complex (PN) 2Ti$$\equiv$$N$$\equiv$$N$$\equiv$$Ti(PN) 2 (2) and a strong reductant. Complete N-atom transfer reactions could also be observed when 1 was treated with ClC(O) tBu and OCCPh 2 to form NC tBu and KNCCPh 2, respectively, along with the terminal oxo complex (PN) 2Ti$$\equiv$$O, which was also characterized. A combination of solid state 15N NMR (MAS) and theoretical studies allowed us to understand the shielding effect of the counter cation in dimer 1, the monomer [K(18-crown-6)][(PN) 2Ti$$\equiv$$N], and the discrete salt [K(2,2,2-Kryptofix)][(PN) 2Ti$$\equiv$$N] as well as the origin of the highly downfield 15N NMR resonance when shifting from dimer to monomer to a terminal nitride (discrete salt). The upfield shift of 15N nitride resonance in the 15N NMR spectrum was found to be linked to the K + induced electronic structural change of the titanium-nitride functionality by using a combination of MO analysis and quantum chemical analysis of the corresponding shielding tensors.

Authors:
 [1];  [2]; ORCiD logo [1];  [1];  [3];  [1];  [1];  [1]
  1. Univ. of Pennsylvania, Philadelphia, PA (United States). Dept. of Chemistry
  2. Free University of Brussels (VUB) Brussels (Belgium). General Chemistry (ALGC)
  3. Queen's Univ., Kingston, ON (Canada). Dept. of Chemistry
Publication Date:
Research Org.:
Univ. of Pennsylvania, Philadelphia, PA (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22). Chemical Sciences, Geosciences & Biosciences Division; Research Foundation Flanders (FWO), Brussels (Belgium)
OSTI Identifier:
1423561
Grant/Contract Number:  
FG02-07ER15893
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Chemical Science
Additional Journal Information:
Journal Volume: 8; Journal Issue: 2; Journal ID: ISSN 2041-6520
Publisher:
Royal Society of Chemistry
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY

Citation Formats

Grant, Lauren N., Pinter, Balazs, Kurogi, Takashi, Carroll, Maria E., Wu, Gang, Manor, Brian C., Carroll, Patrick J., and Mindiola, Daniel J. Molecular titanium nitrides: nucleophiles unleashed. United States: N. p., 2017. Web. doi:10.1039/c6sc03422e.
Grant, Lauren N., Pinter, Balazs, Kurogi, Takashi, Carroll, Maria E., Wu, Gang, Manor, Brian C., Carroll, Patrick J., & Mindiola, Daniel J. Molecular titanium nitrides: nucleophiles unleashed. United States. doi:10.1039/c6sc03422e.
Grant, Lauren N., Pinter, Balazs, Kurogi, Takashi, Carroll, Maria E., Wu, Gang, Manor, Brian C., Carroll, Patrick J., and Mindiola, Daniel J. Mon . "Molecular titanium nitrides: nucleophiles unleashed". United States. doi:10.1039/c6sc03422e. https://www.osti.gov/servlets/purl/1423561.
@article{osti_1423561,
title = {Molecular titanium nitrides: nucleophiles unleashed},
author = {Grant, Lauren N. and Pinter, Balazs and Kurogi, Takashi and Carroll, Maria E. and Wu, Gang and Manor, Brian C. and Carroll, Patrick J. and Mindiola, Daniel J.},
abstractNote = {In this contribution we present reactivity studies of a rare example of a titanium salt, in the form of [μ2-K(OEt2)]2[(PN)2Ti$\equiv$N]2 (1) (PN- = N-(2-(diisopropylphosphino)-4-methylphenyl)-2,4,6-trimethylanilide) to produce a series of imide moieties including rare examples such as methylimido, borylimido, phosphonylimido, and a parent imido. For the latter, using various weak acids allowed us to narrow the pKa range of the NH group in (PN)2Ti$\equiv$NH to be between 26–36. Complex 1 could be produced by a reductively promoted elimination of N2 from the azide precursor (PN)2TiN3, whereas reductive splitting of N2 could not be achieved using the complex (PN)2Ti$\equiv$N$\equiv$N$\equiv$Ti(PN)2 (2) and a strong reductant. Complete N-atom transfer reactions could also be observed when 1 was treated with ClC(O)tBu and OCCPh2 to form NCtBu and KNCCPh2, respectively, along with the terminal oxo complex (PN)2Ti$\equiv$O, which was also characterized. A combination of solid state 15N NMR (MAS) and theoretical studies allowed us to understand the shielding effect of the counter cation in dimer 1, the monomer [K(18-crown-6)][(PN)2Ti$\equiv$N], and the discrete salt [K(2,2,2-Kryptofix)][(PN)2Ti$\equiv$N] as well as the origin of the highly downfield 15N NMR resonance when shifting from dimer to monomer to a terminal nitride (discrete salt). The upfield shift of 15Nnitride resonance in the 15N NMR spectrum was found to be linked to the K+ induced electronic structural change of the titanium-nitride functionality by using a combination of MO analysis and quantum chemical analysis of the corresponding shielding tensors.},
doi = {10.1039/c6sc03422e},
journal = {Chemical Science},
number = 2,
volume = 8,
place = {United States},
year = {Mon Jan 30 00:00:00 EST 2017},
month = {Mon Jan 30 00:00:00 EST 2017}
}

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