High-Frequency ¹H NMR Chemical Shifts of Sn^II and Pb^II Hydrides Induced by Relativistic Effects: Quest for Pb^II Hydrides

Abstract

The role of relativistic effects on H NMR chemical shifts of Sn and Pb hydrides is investigated by using fully relativistic DFT calculations. The stability of possible Pb hydride isomers is studied together with their H NMR chemical shifts, which are predicted in the high-frequency region, up to 90 ppm. TheseH signals are dictated by sizable relativistic contributions due to spin-orbit coupling at the heavy atom and can be as large as 80 ppm for a hydrogen atom bound to Pb. Such high-frequency H NMR chemical shifts of Pb hydride resonances cannot be detected in the H NMR spectra with standard experimental setup. ExtendedH NMR spectral ranges are thus suggested for studies of Pb compounds. Modulation of spin-orbit relativistic contribution to H NMR chemical shift is found to be important also in the experimentally known Sn hydrides. Because the H NMR chemical shifts were found to be rather sensitive to the changes in the coordination sphere of the central metal in both Sn and Pb hydrides, their application for structural investigation is suggested.

Hydridoorganostannylene Coordination: Group 4 Metallocene Dichloride Reduction in Reaction with Organodihydridostannate Anions

“…In this example, the low-field shift could be explained with the influence of the heavy atom on the light atom chemical shift. [31] In the 119 Sn NMR spectrum of 7,t wo signals, ad oublet (1484 ppm, 1 J 119SnÀH = 550 Hz) and as inglet (1789 ppm), were found. The cationic Ar*Sn moiety exhibits the signala tl ower field, compared to the signalo ft he coordinated stannylene.…”

“…For comparison, osmium complex [Cp*( i Pr 3 P)HOs=SnH(trip)] showed a 1 H NMR signal for the Sn−H moiety at 19.4 ppm. In this example, the low‐field shift could be explained with the influence of the heavy atom on the light atom chemical shift …”

Four-component relativistic time-dependent density-functional theory using a stable noncollinear DFT ansatz applicable to both closed- and open-shell systems

“…18,19 Furthermore, the present authors have demonstrated that a four-component methodology is applicable to systems with up to 100 atoms, for calculation of nuclear magnetic resonance and electron paramagnetic resonance parameters. [20][21][22][23][24] Relativistic approaches to LR-TDDFT can be loosely classified using a combination of two criteria. The a) Electronic mail: stanislav.komorovsky@savba.sk first criterion is the method by which SOC and other relativistic effects are accounted for.…”

Long‐range relativistic heavy atom effect on 1H NMR chemical shifts of selenium‐ and tellurium‐containing compounds

“…At the first time HALA effect on proton NMR shielding constants was investigated as earlier as in the beginning of 1970s in hydrogen halides by Morishima et al The abnormal bias of the proton chemical shift in hydrogen halides (HX) ongoing from X = F to I, has been accounted for within the third‐order perturbation theory . After a while it has been established that relativistically induced proton chemical shift originates mainly from the spin‐orbit coupling (SOC) at the heavy atom . Spin‐orbit relativistic corrections to proton shielding constants, calculated by Morishima et al using semi‐empirical SCF‐LCAO MO approximation, were found to be 0.37 ppm for HF, 0.59 ppm for HCl, 2.98 ppm for HBr, and 8.21 ppm for HI molecules.…”

“…It has been noticed that 1 H NMR chemical shifts are highly sensitive to the presence of heavy atoms . At the first time HALA effect on proton NMR shielding constants was investigated as earlier as in the beginning of 1970s in hydrogen halides by Morishima et al The abnormal bias of the proton chemical shift in hydrogen halides (HX) ongoing from X = F to I, has been accounted for within the third‐order perturbation theory .…”