Anton, J.

Pershina, V.

GSI Repository

GSITemplate2007 Theoretical Predictions of Properties and Gas-Phase Behaviour of Carbonyl Complexes of Group-6 Elements Cr, Mo, W, and Element 106, Sg  V. Pershina1 and J. Anton2   1GSI, Darmstadt, Germany; 2Institut für Elektrochemie, Universität Ulm, Germany.      Up to now, experimental gas-phase chemical studies were performed for elements 104 (Rf) through 108 (Hs), 112 (Cn) and 114 (Fl) [1]. A search for a new class of volatile species suitable for gas-phase chromatography studies resulted in the idea to synthesize carbonyl com-plexes of the heaviest elements. Accordingly, carbonyl complexes of Mo, W and Os, homologs of Sg and Hs, respectively, were synthesized and studied on their vola-tility by using both the isothermal (IC) and thermochro-matography (TC) techniques [2].  Theoretical predictions of gas-phase properties and chromatography behaviour of the heaviest elements and their homologs has been a subject of our long-term re-search [3]. In the present work, we predict properties of group-6 M(CO)6 (M = Cr, Mo, W, and Sg) and their ad-sorption behaviour on quartz for future gas-phase chroma-tography experiments. For calculations, we used our 4-component, fully relativistic, Density Functional Theory method developed within the non-collinear spin-polarized formalism [4]. For calculations of the adsorption energy of the molecules on a neutral (quartz) surface, the follow-ing model for a molecule-slab interaction was used [5]:   31121163)(xIPIPHxEmolslabmolads++−−=∆−= αεε       Here, ε  is the dielectric constant of the surface material, IPmol and IPslab are ionization potentials of the molecule and surface material, respectively, αmol is molecular po-larizability and x is the molecule - surface interaction dis-tance estimated using molecular bond lengths.    Results of the calculations of molecular properties (also in comparison with other calculations [6]) needed for predictions of adsorption are given in Tables 1 and 2.  Table 1. Calculated and experimental bond lengths, Re (in Å), of M(CO)6 (M = Cr, Mo, W, and Sg)  Method Re(M-C) Re(C-O) Cr(CO)6 4c-DFT 1.913 1.152  exp. 1.918 1.141 Mo(CO)6 4c-DFT 2.067 1.152  RECP CCSD(T)a 2.076 1.147  exp. 2.063 1.145 W(CO)6 4c-DFT 2.062 1.153  RECP CCSD(T)a 2.065 1.148  exp. 2.058 1.148 Sg(CO)6 4c-DFT 2.123 1.154  RECP CCSD(T)a 2.112 1.150 a Ref. [6]. Table 2. Ionization potentials, IP (in eV), average po-larizabilities, α (in a.u.), molecule-surface adsorption dis-tances, x (in Å), and adsorption enthalpies, -∆Hads (in kJ/mol), of M(CO)6 (M = Cr, Mo, W, and Sg) on quartz  IP <α> x -∆Hads Cr(CO)6 9.07 133.24 2.695 45.4 ± 2.5 Mo(CO)6 9.003 156.41 2.784 48.1 ± 2.5     42.5 ± 2.5a W(CO)6 8.925 151.54 2.781 46.5 ± 2.5b Sg(CO)6 8.631 159.43 2.82 46.2 ± 2.5 a IC experiment [2]; b TC experiment [2]. The data show that the electronic structure of Sg(CO)6 is very similar to those of the Mo and W homologs. Ac-cordingly, its volatility should also be very similar to those of the lighter homologs (Table 2). Fig. 1 shows that, indeed, all the homologs will have similar, within the er-ror bars, ∆Hads(M) on quartz. 394143454749510 50 100 150Z-∆Hads, kJ/molMo Cr W Sg      Fig. 1. Predicted (solid line) and measured (dashed line: the open rhomboid is the IC measurements; the open square is the TC ones [2]) adsorption enthalpies of M(CO)6 (M = Cr, Mo, W, and Sg) on quartz. References [1] A. Türler and V. Pershina, Chem. Rev., in print [2]  J. Even, et al. Inorg. Chem. 51, 6431 (2012). [3] V. Pershina, Radiochim. Acta 99, 459 (2011). [4] J. Anton, et al., Phys. Rev. A 69, 012505 (2004). [5] V. Pershina and T. Bastug, Chem. Phys. 311, 139 (2005) [6] C. N. Nash, B. E. Bursten, J. Am. Chem. Soc., 121, 10830 (1999). GSI SCIENTIFIC REPORT 2012 PHN-ENNA-THEORY-09223

Theoretical Predictions of Properties and Gas-Phase Behaviour of Carbonyl Complexes of Group-6 Elements Cr, Mo, W, and Element 106, Sg

http://repository.gsi.de/record/52122/files/PHN-ENNA-THEORY-09.pdf

Theoretical Predictions of Properties and Gas-Phase Behaviour of Carbonyl Complexes of Group-6 Elements Cr, Mo, W, and Element 106, Sg

Abstract

Similar works

Full text

Available Versions

GSI Repository