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Title: End-On Bridging Dinitrogen Complex of Scandium

Abstract

The first (N=N) 2- complex of a rare-earth metal with an end-on dinitrogen bridge, {K(crypt)} 2{[(R 2N) 3Sc] 2[μ-η 11-n 2]} (crypt = 2.2.2-cryptand, R = SiMe 3), has been isolated from the reduction of Sc(NR 2) 3 under dinitrogen at —35 °C and characterized by X-ray crystallography. The structure differs from the characteristic side-on structures previously observed for over 40 crystallographically-characterized rare-earth metal (N=N) 2- complexes of formula [A 2Ln(THF) x] 2[μ-η 22-N 2] (Ln = Sc, Y, and lanthanides; x = 0, 1; A = anionic ligand such as amide, cyclopentadienide, and aryloxide). The 1.221(3) Å N—N distance and the 1644 cm -1 Raman stretch are consistent with the presence of an (N=N) 2- bridge. The observed paramagnetism of the complex by NMR spectroscopy and Evans method measurements is consistent with DFT calculations that suggest a triplet( 3A 2) ground state in D 3 symmetry involving two degenerate Sc—N 2—Sc bonding orbitals. Upon brief exposure of the orange Sc 3+ bridging dinitrogen complex to UV-light, photolysis to form the monomeric Sc 2+ complex, [K(crypt)][Sc(NR 2) 3], was observed. Conversion of the Sc 2+ complex to the SO 3+ dinitrogen complex was not observed with this cryptmore » system, but it did occur with the 18-crown-6 (crown) analog which formed {K(crown)} 2{[(R 2N) 3Sc] 2[μ-η 11-N 2]}. This suggests the importance of the alkali metal chelating agent in the reversibility of dinitrogen binding in this scandium system.« less

Authors:
ORCiD logo [1]; ORCiD logo [1];  [1]; ORCiD logo [2]; ORCiD logo [1]; ORCiD logo [1]
  1. Univ. of California, Irvine, CA (United States)
  2. Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
Publication Date:
Research Org.:
Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
Sponsoring Org.:
USDOE National Nuclear Security Administration (NNSA)
OSTI Identifier:
1473943
Report Number(s):
SAND-2018-10055J
Journal ID: ISSN 0002-7863; 667860
Grant/Contract Number:  
AC04-94AL85000
Resource Type:
Accepted Manuscript
Journal Name:
Journal of the American Chemical Society
Additional Journal Information:
Journal Volume: 139; Journal Issue: 42; Journal ID: ISSN 0002-7863
Publisher:
American Chemical Society (ACS)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY

Citation Formats

Woen, David H., Chen, Guo P., Ziller, Joseph W., Boyle, Timothy J., Furche, Filipp, and Evans, William J. End-On Bridging Dinitrogen Complex of Scandium. United States: N. p., 2017. Web. doi:10.1021/jacs.7b08456.
Woen, David H., Chen, Guo P., Ziller, Joseph W., Boyle, Timothy J., Furche, Filipp, & Evans, William J. End-On Bridging Dinitrogen Complex of Scandium. United States. doi:10.1021/jacs.7b08456.
Woen, David H., Chen, Guo P., Ziller, Joseph W., Boyle, Timothy J., Furche, Filipp, and Evans, William J. Thu . "End-On Bridging Dinitrogen Complex of Scandium". United States. doi:10.1021/jacs.7b08456. https://www.osti.gov/servlets/purl/1473943.
@article{osti_1473943,
title = {End-On Bridging Dinitrogen Complex of Scandium},
author = {Woen, David H. and Chen, Guo P. and Ziller, Joseph W. and Boyle, Timothy J. and Furche, Filipp and Evans, William J.},
abstractNote = {The first (N=N)2- complex of a rare-earth metal with an end-on dinitrogen bridge, {K(crypt)}2{[(R2N)3Sc]2[μ-η1:η1-n2]} (crypt = 2.2.2-cryptand, R = SiMe3), has been isolated from the reduction of Sc(NR2)3 under dinitrogen at —35 °C and characterized by X-ray crystallography. The structure differs from the characteristic side-on structures previously observed for over 40 crystallographically-characterized rare-earth metal (N=N)2- complexes of formula [A2Ln(THF)x]2[μ-η2:η2-N2] (Ln = Sc, Y, and lanthanides; x = 0, 1; A = anionic ligand such as amide, cyclopentadienide, and aryloxide). The 1.221(3) Å N—N distance and the 1644 cm-1 Raman stretch are consistent with the presence of an (N=N)2- bridge. The observed paramagnetism of the complex by NMR spectroscopy and Evans method measurements is consistent with DFT calculations that suggest a triplet( 3A2) ground state in D3 symmetry involving two degenerate Sc—N2—Sc bonding orbitals. Upon brief exposure of the orange Sc3+ bridging dinitrogen complex to UV-light, photolysis to form the monomeric Sc2+ complex, [K(crypt)][Sc(NR2)3], was observed. Conversion of the Sc2+ complex to the SO3+ dinitrogen complex was not observed with this crypt system, but it did occur with the 18-crown-6 (crown) analog which formed {K(crown)}2{[(R2N)3Sc]2[μ-η1:η1-N2]}. This suggests the importance of the alkali metal chelating agent in the reversibility of dinitrogen binding in this scandium system.},
doi = {10.1021/jacs.7b08456},
journal = {Journal of the American Chemical Society},
number = 42,
volume = 139,
place = {United States},
year = {2017},
month = {9}
}

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Figures / Tables:

Figure 1 Figure 1: Thermal ellipsoid plot of the dianion of {K(crypt)} 2 {[(NR2)3Sc]2[$µ$-$\eta$1:$\eta$1-N2]},2-crypt, drawn at 50% probability level. The two [K(crypt)]+ cations, three co-crystallized Et20 molecules, and hydrogen atoms are omitted for clarity. Sc 1— N1 = 2.032(3) Å; Sc2—N2 = 2.030(3) Å; N1—N2 = 1.221(3) Å. See Supporting Information formore » details.« less

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