A Study of Transition‐Metal Organometallic Complexes Combining 35Cl Solid‐State NMR Spectroscopy and 35Cl NQR Spectroscopy and First‐Principles DFT Calculations |
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Authors: | Dr. Karen E. Johnston Christopher A. O'Keefe Dr. Régis M. Gauvin Dr. Julien Trébosc Dr. Laurent Delevoye Prof. Jean‐Paul Amoureux Dr. Nicolas Popoff Dr. Mostafa Taoufik Dr. Konstantin Oudatchin Prof. Robert W. Schurko |
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Affiliation: | 1. Department of Chemistry and Biochemistry, University of Windsor, Windsor, Ontario, N9B 3P4 (Canada);2. Université Lille Nord de France, CNRS UMR8181, Unité de Catalyse et de Chimie du Solide, UCCS USTL, 59655 Villeneuve d'Ascq (France);3. Laboratoire de Chimie, Catalyse, Polymères et Procédés (UMR‐C2P2‐5265 CNRS/ESCPE‐Lyon/UCBL) ESCPE Lyon, 30843, Boulevard du 11 Novembre 1918, 69616 Villeurbanne Cedex (France);4. Steacie Institute for Molecular Sciences, National Research Council Canada, 100 Sussex Drive, Ottawa, Ontario, K1A OR6 (Canada) |
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Abstract: | A series of transition‐metal organometallic complexes with commonly occurring metal? chlorine bonding motifs were characterized using 35Cl solid‐state NMR (SSNMR) spectroscopy, 35Cl nuclear quadrupole resonance (NQR) spectroscopy, and first‐principles density functional theory (DFT) calculations of NMR interaction tensors. Static 35Cl ultra‐wideline NMR spectra were acquired in a piecewise manner at standard (9.4 T) and high (21.1 T) magnetic field strengths using the WURST‐QCPMG pulse sequence. The 35Cl electric field gradient (EFG) and chemical shielding (CS) tensor parameters were readily extracted from analytical simulations of the spectra; in particular, the quadrupolar parameters are shown to be very sensitive to structural differences, and can easily differentiate between chlorine atoms in bridging and terminal bonding environments. 35Cl NQR spectra were acquired for many of the complexes, which aided in resolving structurally similar, yet crystallographically distinct and magnetically inequivalent chlorine sites, and with the interpretation and assignment of 35Cl SSNMR spectra. 35Cl EFG tensors obtained from first‐principles DFT calculations are consistently in good agreement with experiment, highlighting the importance of using a combined approach of theoretical and experimental methods for structural characterization. Finally, a preliminary example of a 35Cl SSNMR spectrum of a transition‐metal species (TiCl4) diluted and supported on non‐porous silica is presented. The combination of 35Cl SSNMR and 35Cl NQR spectroscopy and DFT calculations is shown to be a promising and simple methodology for the characterization of all manner of chlorine‐containing transition‐metal complexes, in pure, impure bulk and supported forms. |
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Keywords: | chlorine density functional calculations solid‐state NMR spectroscopy structure determination transition metals |
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