Reactivity of Ts and At oxides and oxyhydrides with a gold surface from periodic DFT calculations.

Adsorption energies, Eads, of oxides and oxyhydrides of the superheavy element (SHEs) Ts and of its lighter homologue At on the gold surface are predicted on the basis of relativistic periodic density functional theory calculations via AMS BAND software. The following compounds were considered: MO, MO2, MOO, and MO(OH) (where M = At and Ts). The aim of this study is to support "one-atom-at-a-time" gas-phase chromatography experiments on reactivity/volatility of SHEs. The results obtained indicate that all the molecules investigated should interact fairly strongly with the gold surface, with those of Ts being more reactive than At ones. The similarity in the Eads values of all the considered At compounds would make it challenging to differentiate between them while measuring their adsorption enthalpies, given experimental uncertainty. However, the difference in Eads among Ts compounds is more pronounced, so that one should be able to differentiate between the species.

A theoretical study of the adsorption behavior of superheavy 7p-elements and their compounds on a surface of gold in comparison with their lighter homologs.

Adsorption energies, Eads, of the 7th row superheavy elements (SHEs) Lv through Og, as well as of the homologous species of the 6th row elements Po through Rn on a gold surface are predicted on the basis of relativistic periodic density functional theory calculations via SCM BAND software. Since some of the elements can also form compounds such as hydrides and oxyhydrides under experimental conditions, the Eads values of the MH (M = Bi/Mc, Po/Lv, At/Ts and Rn/Og) and MOH (M = At/Ts and Rn/Og) molecules on a gold surface were also calculated. The aim of this study is to support "one-atom-at-a-time" gas-phase chromatography experiments on the reactivity/volatility of SHEs. The obtained results show that, in agreement with earlier predictions using somewhat different approaches and with experimental results on Hg, Cn and Rn, the adsorption strength of the elements on the Au(111) surface should follow the sequence: Hg > Fl > Og > Cn ≫ Rn, with the Eads values of less than 100 kJ mol-1. The other elements and their compounds under consideration should adsorb much more strongly on the gold surface with Eads values above 160 kJ mol-1, which should make them indistinguishable with respect to Eads in the chromatography column kept at room temperature and lower. However, with the further detector development, investigations of the chemical properties of these short-lived and less volatile SHEs and their compounds at high temperatures should be possible.

Relativistic Coupled-Cluster Calculations of Spectroscopic Properties of Copernicium and Flerovium Monoxides.

Calculations of spectroscopic properties of the CnO and FlO molecules are performed using ab initio all-electron 4c- and 2c-relativistic coupled-cluster approaches with single, double, and perturbative triple excitations. The corresponding calculation for HgO is also accomplished for comparison with the published data. The dependence of the results on the parameters of the basis set and approximations used is investigated in detail. The overall relative uncertainties of the recommended values on the level of 1-2 % are reached. The calculated spectroscopic constants are indicative of the following trend in the reactivity of the oxides HgO>FlO>CnO. This is confirmed by the trend in the adsorption energies, Eads , of these molecules on the surfaces of gold, quartz, and Teflon. The predicted rather low Eads values for the latter case should guarantee their delivery from the recoil chamber to the chemistry set up in gas-phase experiments.

Reactivity of Group 13 Elements Tl and Element 113, Nh, and of Their Hydroxides with Respect to Various Quartz Surfaces from Periodic Relativistic DFT Calculations.

Adsorption properties of group 13 element Tl and the superheavy element Nh, as well of their hydroxides on various modified quartz surfaces, are predicted on the basis of relativistic periodic DFT calculations using the BAND software. The obtained adsorption energies, Eads, of the MOH (M = Tl and Nh) molecules are indicative of the relatively strong interaction of the hydroxides with all the considered quartz surfaces. In contrast, adsorption of the Tl and Nh atoms was found to be significantly weaker. The adsorption strength of both M and MOH (M = Tl and Nh) was shown to increase with the dehydroxylation of the quartz surface. Very good agreement is reached between the calculated Eads(TlOH) of 133 kJ/mol on the fully hydroxylated quartz surface and of 157 kJ/mol on the partially dehydroxylated quartz surface on the one hand and experimental adsorption enthalpies, -ΔHads, of 134/137 ± 5 kJ/mol (at ∼300 °C) and 158 ± 3 kJ/mol (at ∼500 °C), respectively, on the other hand. Thus, we suggest that all the experimental ΔHads values for Tl should be assigned to the adsorption/desorption of the TlOH molecule. For NhOH, its adsorption properties on various quartz surfaces should be very similar to those of TlOH, with slightly smaller Eads values. Adsorption of the Nh atom should, however, be much weaker than that of the Tl atom due to stronger spin-orbit effects in Nh.

Reactivity of superheavy elements Cn and Fl and of their oxides in comparison with homologous species of Hg and Pb, respectively, towards gold and hydroxylated quartz surfaces.

Adsorption energies, Eads, and other properties of atoms and oxides of the superheavy elements (SHEs) Cn and Fl, as well as of the homologous species of Hg and Pb, on Au(111) and fully hydroxylated quartz surfaces are predicted on the basis of 2c-DFT calculations and a periodic slab model using BAND software. The ambition of the work is to interpret the outcome of "one-atom-at-a-time" gas-phase chromatography experiments on the reactivity/volatility of SHEs. The present results with an improved (dispersion corrected) exchange-correlation functional show that, in agreement with our earlier predictions and experimental results on Pb, Hg and Cn, the sequence of the Eads values of the atoms on the gold surface should be Pb ≫ Hg > Fl > Cn, with rather moderate Eads values smaller than 90 kJ mol-1 (except for that for Pb). Oxides of Hg, Cn and Fl should be much more reactive with the gold surface than the corresponding atoms, with Eads values of about 200 kJ mol-1. A striking difference in the geometry of the deposited oxides was found between group 12 and group 14. An analysis of the Eads values for M and MO (M = Hg/Cn and Pb/Fl) on the hydroxylated α-quartz surface enables one to conclude that atoms of Hg, Cn and Fl should not interact with such a surface at room temperature, while Pb should adsorb on it. Oxides of these elements, on the contrary, should strongly adsorb on quartz with Eads ≥ 100 kJ mol-1. The present theoretical data agree with the experimental results on the elemental species of Hg, Cn and Fl.

Reactivity of the Superheavy Element 115, Mc, and Its Lighter Homologue, Bi, with Respect to Gold and Hydroxylated Quartz Surfaces from Periodic Relativistic DFT Calculations: A Comparison with Element 113, Nh.

Adsorption energies (Eads) of the superheavy element (SHE) Mc, its lighter homologue (Bi), as well as of another superheavy element Nh and some lighter homologues of SHEs on gold and hydroxylated quartz surfaces are predicted via periodic relativistic density functional theory calculations. The aim of this study is to support "one-atom-at-a-time" gas-phase chromatography experiments that are examining the reactivity and volatility of Mc. The obtained Eads values of the Bi and Mc atoms on the Au(111) surface are >200 kJ/mol. On the hydroxylated quartz surface, Mc should adsorb with a minimal energy of 58 kJ/mol. On both types of surfaces, Eads(Mc) should be ∼100 kJ/mol smaller than Eads(Bi) due to strong relativistic effects on its valence 7p electrons. A comparison with other SHEs under investigation shows that Mc should adsorb on gold more strongly than Cn, Nh, and Fl, while on quartz, Mc should adsorb like Nh, with both of them absorbing more strongly than volatile Cn and Fl. The highest reactivity of Mc in the row of the 7p elements is caused by the largest orbital and relativistic destabilization and expansion of the 7p3/2 atomic orbital. Using the calculated Eads, the distribution of the Nh and Mc events in the gas-phase chromatography column with quartz and gold-plated detectors is predicted via Monte Carlo simulations. As a result, Mc atoms should be almost 100% adsorbed in the first section of the chromatography column on quartz, while a few atoms of Nh can reach the second part of the column with gold-plated detectors.

Relativistic Effects on the Properties of Lr: A Periodic DFT Study of the Adsorption of Lr on Surfaces of Ta in Comparison with Lu and Tl.

With the aim of finding out whether the predicted 7s27p1/2 ground-state electron configuration of Lr will have an effect on its reactivity, calculations of the adsorption properties of Lr(7s27p), its homologue Lu(6s25d), and the related p element Tl(6s26p) on the surface of Ta were performed using the relativistic periodic ADF BAND suite. The obtained adsorption energies, Eads(M), are in excellent agreement with the measured adsorption enthalpies of Lu and Tl, showing that Lr adsorbs on the surface of Ta similarly to Lu and much differently (215 kJ/mol more strongly) from Tl. An AO population analysis reveals that Lr interacts with the Ta surface preferentially via the 7s AO, with some participation of the 6d as well as 7p1/2 and 7p3/2 AOs. In contrast, Eads(Tl) is governed mainly by the 6p(Tl) AOs. Thus, the present investigations show that Lr should behave like Lu but not like the p element Tl on transition-metal surfaces.

Properties and Reactivity of Hydroxides of Group 13 Elements In, Tl, and Nh from Molecular and Periodic DFT Calculations.

Adsorption energies, Eads, of gaseous hydroxides of In, Tl, and the superheavy element Nh on surfaces of Teflon and gold are predicted using molecular and periodic relativistic DFT calculations. The ambition of the work is to assist related "one atom at a time" gas-phase chromatography experiments on the volatility of NhOH. The obtained low values of Eads(MOH), where M = In, Tl, Nh, on Teflon should guarantee easy transportation of the molecules through the Teflon capillaries from the accelerator to the chemistry setup. Straightforward band-structure DFT calculations using the revPBE-D3(BJ) functional have given an Eads(MOH) value of 161.4 kJ/mol on the Au(111) surface, being indicative of significant molecule-surface interaction. The MOH-gold surface binding is shown to take place via the oxygen atom of the hydroxide, with the oxygen-gold charge density transfer increasing from InOH to NhOH. The trend in Eads(MOH) is shown to be InOH < TlOH < NhOH, caused by increasing molecular dipole moments and decreasing stability of the hydroxides in this row. A trend in Eads of the atoms of these elements on gold is, however, opposite, In > Tl > Nh, caused by the increasing relativistic contraction and stabilization of the np1/2 AO with Z. These opposite trends in Eads(MOH) and Eads(M) in group 13 lead to almost equal Eads(Nh) and Eads(NhOH) values, making identification of Nh, as a type of species, difficult by measuring its adsorption enthalpy on gold.

Reactivity of Superheavy Elements Cn, Nh, and Fl and Their Lighter Homologues Hg, Tl, and Pb, Respectively, with a Gold Surface from Periodic DFT Calculations.

Adsorption energies of superheavy elements (SHEs) Cn, Nh, and Fl and their lighter homologues Hg, Tl, and Pb, respectively, on a Au(111) surface at different adsorbate coverages are predicted via periodic relativistic DFT calculations with the aim of assisting the outcome of related "one-atom-at-a-time" gas-phase chromatography experiments. In agreement with previous DFT studies with the use of a cluster model, the present results for large supercells are indicative of high volatility of Cn. Thus, this element should not interact with the regular Au(111) surface at room temperature but should adsorb on it in a vacancy. Fl should moderately interact with such a surface under ambient conditions, while Nh should be the most reactive element with respect to gold. All three elements should, however, reveal much lower reactivity toward gold than their lighter homologues. The reasons for this are the strong relativistic stabilization and contraction of the 7s1/2 and 7p1/2 AOs. The obtained trend in the adsorption energy, Nh ≫ Fl > Cn, enables one to easily separate these elements from each other, as well as from their lighter homologues using gold or gold/quartz surfaces.

Hexacarbonyls of Mo, W, and Sg: Metal-CO Bonding Revisited.

Calculations of the first bond dissociation energies (FBDEs) and other molecular properties of M(CO)6, where M = Mo, W, and Sg, have been performed using a variety of nonrelativistic and relativistic methods, such as ZORA-DFT, X2c+AMFI-CCSD(T), and Dirac-Coulomb density functional theory. The aim of the study is to assist experiments on the measurements of the FBDE of Sg(CO)6. We have found that, different from the results published earlier, the metal-CO bond in Sg(CO)6 should be weaker than that in W(CO)6. A comparison of the relativistic and nonrelativistic FBDE values, as well as molecular orbital and vibrational frequency analyses within both the nonrelativistic and relativistic approaches, have shown that this is a relativistic, predominantly scalar, effect causing weaker d(M) → π(CO) back-bonding in Sg(CO)6 than in the lighter homologues. Good agreement between the calculated FBDEs in this work and the experimental FBDEs for the Mo and W compounds gives credit to the present FBDE of Sg(CO)6, which should serve as guidance for ongoing experiments.