A study of transition-metal organometallic complexes combining 35Cl solid-state NMR spectroscopy and 35Cl NQR spectroscopy and first-principles DFT calculations

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. Fast and furious: A series of transition-metal organometallic complexes with commonly occurring metal-chlorine bonding motifs were characterized using a combination of 35Cl solid-state NMR (SSNMR) spectroscopy, 35Cl nuclear quadrupole resonance (NQR) spectroscopy and first-principles density functional theory (DFT) calculations. Static 35Cl ultra-wideline NMR spectra were rapidly acquired in a piecewise manner at high magnetic field strengths. Copyright \ua9 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.Peer reviewed: YesNRC publication: Ye