Synthesis of a Bis(thiophenolate)pyridine Ligand and Its Titanium, Zirconium, and Tantalum Complexes

Handle URI:
http://hdl.handle.net/10754/599834
Title:
Synthesis of a Bis(thiophenolate)pyridine Ligand and Its Titanium, Zirconium, and Tantalum Complexes
Authors:
Lenton, Taylor N.; VanderVelde, David G.; Bercaw, John E.
Abstract:
A precursor to a new tridentate LX 2 type ligand, bis(thiophenol)pyridine ((SNS)H 2 = (2-C 6H 4SH) 2-2,6-C 5H 3N), was prepared. Bis(thiophenolate)pyridine complexes of Ti, Zr, and Ta having dialkylamido coligands were synthesized and structurally characterized. The zirconium complex (SNS)Zr(NMe 2) 2 (4) displays C 2 symmetry in the solid state, unlike a related bis(phenolate)pyridine compound, C s-symmetric (ONO)Ti(NMe 2) 2. This change is likely the result of strain about the sulfur atom in the six-membered chelate with longer metal-sulfur and carbon-sulfur bonds. Solid-state structures of tantalum complexes (SNS)Ta(NMe 2) 3 (5) and (SNS)TaCl(NEt 2) 2 (6) also display pronounced C 2 twisting of the SNS ligand. 1D and 2D NMR experiments show that 5 is fluxional, with rotation about the Ta-N(amide) bonds occurring on the NMR time scale that interchange the equatorial amide methyl groups (ΔG ‡ 393 = 25.0(3) kcal/mol). The fluxional behavior of 6 in solution was also studied by variable-temperature 1H NMR. Observation of separate signals for the diastereotopic protons of the methylene unit of the diethylamide indicates that the complex remains locked on the NMR time scale in one diastereomeric conformation at temperatures below -50 °C, fast rotation about the equatorial amide Ta-N bonds occurs at higher temperature (ΔG ‡ 393 = 13.4(3) kcal/mol), and exchange of diastereomeric methylene protons occurs via inversion at Ta that interconverts antipodes (ΔG ‡ 393 ≈ 14(1) kcal/mol). © 2012 American Chemical Society.
Citation:
Lenton TN, VanderVelde DG, Bercaw JE (2012) Synthesis of a Bis(thiophenolate)pyridine Ligand and Its Titanium, Zirconium, and Tantalum Complexes. Organometallics 31: 7492–7499. Available: http://dx.doi.org/10.1021/om300789h.
Publisher:
American Chemical Society (ACS)
Journal:
Organometallics
Issue Date:
12-Nov-2012
DOI:
10.1021/om300789h
Type:
Article
ISSN:
0276-7333; 1520-6041
Sponsors:
This work was supported by a KAUST Center-In-Development Grant to King Fahd University of Petroleum and Minerals (Dhahran, Saudi Arabia) and the USDOE Office of Basic Energy Sciences (Grant No. DE-FG03-85ER13431). We thank Ian A. Tonks and Matthew S. Winston for helpful discussions related to the research present in this paper. We also thank Lawrence M. Henling and Michael W. Day of Caltech for solving crystal structures. The Bruker KAPPA APEXII X-ray diffractometer was purchased via an NSF CRIF:MU award to the California Institute of Technology (CHE-0639094).
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Full metadata record

DC FieldValue Language
dc.contributor.authorLenton, Taylor N.en
dc.contributor.authorVanderVelde, David G.en
dc.contributor.authorBercaw, John E.en
dc.date.accessioned2016-02-28T06:10:56Zen
dc.date.available2016-02-28T06:10:56Zen
dc.date.issued2012-11-12en
dc.identifier.citationLenton TN, VanderVelde DG, Bercaw JE (2012) Synthesis of a Bis(thiophenolate)pyridine Ligand and Its Titanium, Zirconium, and Tantalum Complexes. Organometallics 31: 7492–7499. Available: http://dx.doi.org/10.1021/om300789h.en
dc.identifier.issn0276-7333en
dc.identifier.issn1520-6041en
dc.identifier.doi10.1021/om300789hen
dc.identifier.urihttp://hdl.handle.net/10754/599834en
dc.description.abstractA precursor to a new tridentate LX 2 type ligand, bis(thiophenol)pyridine ((SNS)H 2 = (2-C 6H 4SH) 2-2,6-C 5H 3N), was prepared. Bis(thiophenolate)pyridine complexes of Ti, Zr, and Ta having dialkylamido coligands were synthesized and structurally characterized. The zirconium complex (SNS)Zr(NMe 2) 2 (4) displays C 2 symmetry in the solid state, unlike a related bis(phenolate)pyridine compound, C s-symmetric (ONO)Ti(NMe 2) 2. This change is likely the result of strain about the sulfur atom in the six-membered chelate with longer metal-sulfur and carbon-sulfur bonds. Solid-state structures of tantalum complexes (SNS)Ta(NMe 2) 3 (5) and (SNS)TaCl(NEt 2) 2 (6) also display pronounced C 2 twisting of the SNS ligand. 1D and 2D NMR experiments show that 5 is fluxional, with rotation about the Ta-N(amide) bonds occurring on the NMR time scale that interchange the equatorial amide methyl groups (ΔG ‡ 393 = 25.0(3) kcal/mol). The fluxional behavior of 6 in solution was also studied by variable-temperature 1H NMR. Observation of separate signals for the diastereotopic protons of the methylene unit of the diethylamide indicates that the complex remains locked on the NMR time scale in one diastereomeric conformation at temperatures below -50 °C, fast rotation about the equatorial amide Ta-N bonds occurs at higher temperature (ΔG ‡ 393 = 13.4(3) kcal/mol), and exchange of diastereomeric methylene protons occurs via inversion at Ta that interconverts antipodes (ΔG ‡ 393 ≈ 14(1) kcal/mol). © 2012 American Chemical Society.en
dc.description.sponsorshipThis work was supported by a KAUST Center-In-Development Grant to King Fahd University of Petroleum and Minerals (Dhahran, Saudi Arabia) and the USDOE Office of Basic Energy Sciences (Grant No. DE-FG03-85ER13431). We thank Ian A. Tonks and Matthew S. Winston for helpful discussions related to the research present in this paper. We also thank Lawrence M. Henling and Michael W. Day of Caltech for solving crystal structures. The Bruker KAPPA APEXII X-ray diffractometer was purchased via an NSF CRIF:MU award to the California Institute of Technology (CHE-0639094).en
dc.publisherAmerican Chemical Society (ACS)en
dc.titleSynthesis of a Bis(thiophenolate)pyridine Ligand and Its Titanium, Zirconium, and Tantalum Complexesen
dc.typeArticleen
dc.identifier.journalOrganometallicsen
dc.contributor.institutionCalifornia Institute of Technology, Pasadena, United Statesen
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