Shielding and Indirect Spin–Spin Coupling Tensors in the Presence of a Heavy Atom: An Experimental and Theoretical Study of Bis(phenylethynyl)mercury

Abstract

Magnetic shielding and indirect spin-spin coupling phenomena are tensorial properties and both their isotropic and anisotropic parts do affect NMR spectra. The involved interaction tensors, σ and J, can nowadays be theoretically calculated, although the reliability of such methods in the case of anisotropic parameters, Δσ and ΔJ, in systems involving heavy nuclei, yet demands testing. In this communication the results of the experimental and theoretical investigations of bis(phenylethynyl)mercury (I) labeled with (13)C isotope at positions neighboring Hg are reported. The theoretical calculations of molecular geometry and values of NMR parameters for I have been performed by the ZORA/DFT method, including the relativistic scalar and spin-orbit coupling contributions, using the PBE0 functional and TZP (or jcpl) basis set. These values have been confronted with the experimentally measured ones. The isotropic parameters have been measured by the standard (13)C and (199)Hg NMR spectra. The shielding anisotropies for the atoms in the central part of molecule I have been determined in a liquid sample using magnetic relaxation measurements. The relaxation data have been interpreted within the rotational diffusion theory, assuming the symmetrical top reorientation model. The anisotropies of one-bond (13)C-(199)Hg and two-bond (13)C-Hg-(13)C spin-spin couplings have been determined exploiting the temperature-dependent (13)C NMR spectra of I in the ZLI1167 liquid-crystal phase. We have found that our theoretical calculations reproduce experimental values of both isotropic and anisotropic NMR parameters very well.

Computational 1H NMR: Part 1. Theoretical background

“…Relativistic effects in NMR chemical shifts and spin–spin coupling constants known as “Heavy Atom on Light Atom” (HALA) effects were evaluated in a great number of molecules containing “heavy” elements, see some salient earlier publications together with some more recent and most recent ones and many other related papers, which are not cited herewith in full in view of their multiplicity.…”

“…Relativistic effects in NMR chemical shifts and spinspin coupling constants known as "Heavy Atom on Light Atom" (HALA) effects were evaluated in a great number of molecules containing "heavy" elements, see some salient earlier publications [117][118][119][120][121][122][123][124][125][126] together with some more recent and most recent ones [127][128][129][130][131][132][133][134][135][136][137][138][139][140][141][142][143][144][145] and many other related papers, [146][147][148][149][150][151][152][153][154][155] which are not cited herewith in full in view of their multiplicity.…”

Regioselective Mercury(I)/Palladium(II)-Catalyzed Single-Step Approach for the Synthesis of Imines and 2-Substituted Indoles

“…The properties of Hg(0) and Hg(II) salts have been examined [ 76 ], and these species have many chemical and industrial applications [ 77 , 78 , 79 ], including chemical transformations [ 80 , 81 , 82 ]. Curiously, the use of Hg(I) in organic synthesis is surprisingly rare and limited [ 83 , 84 ].…”

Insight and performance of LC‐DFT vs DFT in the NMR shielding and chemical shift calculations: Case of CHClCHCF3

“…Nuclear magnetic resonance spectroscopy (NMR) has become a powerful tool for obtaining information concerning the structure and dynamics of molecules. [ 1–37 ] In the field of molecular modeling, the assessment of the NMR shielding was addressed by Ramsey in the early 1950s. [ 5,9 ] Thereafter, it has been modernized by Stevens et al in 1963.…”