An Investigation of Chlorine Ligands in Transition-Metal Complexes via 35Cl Solid-State NMR and Density Functional Theory Calculations

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• 作者：Christopher A. O鈥橩eefe ; Karen E. Johnston ; Kiplangat Sutter ; Jochen Autschbach ; R茅gis Gauvin ; Julien Tr茅bosc ; Laurent Delevoye ; Nicolas Popoff ; Mostafa Taoufik ; Konstantin Oudatchin ; Robert W. Schurko
• 刊名：Inorganic Chemistry
• 出版年：2014
• 出版时间：September 15, 2014
• 年：2014
• 卷：53
• 期：18
• 页码：9581-9597
• 全文大小：882K
• ISSN：1520-510X

文摘

Chlorine ligands in a variety of diamagnetic transition-metal (TM) complexes in common structural motifs were studied using ³⁵Cl solid-state NMR (SSNMR), and insight into the origin of the observed ³⁵Cl NMR parameters was gained through first-principles density functional theory (DFT) calculations. The WURST-CPMG pulse sequence and the variable-offset cumulative spectrum (VOCS) methods were used to acquire static ³⁵Cl SSNMR powder patterns at both standard (9.4 T) and ultrahigh (21.1 T) magnetic field strengths, with the latter affording higher signal-to-noise ratios (S/N) and reduced experimental times (i.e., <1 h). Analytical simulations were performed to extract the ³⁵Cl electric field gradient (EFG) tensor and chemical shift (CS) tensor parameters. It was found that the chlorine ligands in various bonding environments (i.e., bridging, terminal-axial, and terminal-equatorial) have drastically different ³⁵Cl EFG tensor parameters, suggesting that ³⁵Cl SSNMR is ideal for characterizing chlorine ligands in TM complexes. A detailed localized molecular orbital (LMO) analysis was completed for NbCl₅. It was found that the contributions of individual molecular orbitals must be considered to fully explain the observed EFG parameters, thereby negating simple arguments based on comparison of bond lengths and angles. Finally, we discuss the application of ³⁵Cl SSNMR for the structural characterization of WCl₆ that has been grafted onto a silica support material. The resulting tungsten-chloride surface species is shown to be structurally distinct from the parent compound.