2H NMR calculations on polynuclear transition metal complexes: on the influence of local symmetry and other factors

Abstract

It is now well-known that (2)H solid-state NMR techniques can bring a better understanding of the interaction of deuterium with metal atoms in organometallic mononuclear complexes, clusters or nanoparticles. In that context, we have recently obtained experimental quadrupolar coupling constants and asymmetry parameters characteristic of deuterium atoms involved in various bonding situations in ruthenium clusters, namely D(4)Ru(4)(CO)(12), D(2)Ru(6)(CO)(18) and other related compounds [Gutmann et al., J. Am. Chem. Soc., 2010, 132, 11759], which are model compounds for edge-bridging (μ-H) and face-capping (μ(3)-H) coordination types on ruthenium surfaces. The present work is in line with density functional theory (DFT) calculations of the electric field gradient (EFG) tensors in deuterated organometallic ruthenium complexes. The comparison of quadrupolar coupling constants shows an excellent agreement between calculated and observed values. This confirms that DFT is a method of choice for the analysis of deuterium NMR spectra. Such calculations are achieved on a large number of ruthenium clusters in order to obtain quadrupolar coupling constants characteristic of a given coordination type: terminal-D, η(2)-D(2), μ-D, μ(3)-D as well as μ(4)-D and μ(6)-D (i.e. interstitial deuterides). Given the dependence of such NMR parameters mainly on local symmetry, these results are expected to remain valid for large assemblies of ruthenium atoms, such as organometallic ruthenium nanoparticles.

Carboxylic acid-capped ruthenium nanoparticles: experimental and theoretical case study with ethanoic acid

“…Due to its position and broadness, as well as to previous surface state studies on ligandcapped ruthenium NPs, this slightly shifted signal in comparison to that of free CH 3 COOH can be attributed to the methyl group protons of ethanoic acid strongly bonded to the ruthenium NPs surface. This assignment is confirmed by DFT chemical shifts calculated for protonated/unprotonated carboxylic acid free and coordinated onto a model [Ru 6 ] cluster (see Figure 2 and Table SI.8), the molecular cluster strategy for such NMR calculations having been validated by us [23][24][25][26][27] and others. 28 The protons of the methyl group of free ethanoic acid dimer are found to resonate at 1.9 ppm as experimentally observed (1.93 ppm).…”

Hydrogenation mechanism of carbon dioxide and carbon monoxide on Ru(0001) surface: a density functional theory study

“…The energies of the initial states, transition states and nal states were corrected by zero point energies (ZPE). The adsorption energies (E ads ) of the species adsorbed on the Ru(0001) surface were calculated from the energy difference between the optimized surface containing the adsorbate (E surface+adsorbate ) and the optimized clean surface with the adsorbing molecule optimized in the gas state (E surface + E adsorbing molecule ), 39,40 as shown in the following equation:…”

Gas phase 1H NMR studies and kinetic modeling of dihydrogen isotope equilibration catalyzed by Ru-nanoparticles under normal conditions: dissociative vs. associative exchange

“…Moreover, some methylene groups of the HDA ligands are partially deuterated as a consequence of intermediate binding to the surface followed by H/D exchange. 25 Further 2 H solid state NMR 26,27 and computational studies 11,28 of Ru-nanoparticles and model systems demonstrated not only the occurrence of surface hydrides of the terminal RuH, bridging Ru(m 2 -H) and bridging Ru(m 3 -H) type but also of surface Ru(Z 2 -H 2 /HD/D 2 ) dihydrogen complexes. The latter should be subject to rotational H 2 29 or D 2 tunneling.…”