Bonding in Mercury Molecules Described by the Normalized Elimination of the Small Component and Coupled Cluster Theory

Abstract

Bond dissociation energies (BDEs) of neutral HgX and cationic HgX+ molecules range from less than a kcal mol−1 to as much as 60 kcal mol−1. Using NESC/CCSD(T) [normalized elimination of the small component and coupled‐cluster theory with all single and double excitations and a perturbative treatment of the triple excitations] in combination with triple‐zeta basis sets, bonding in 28 mercury molecules HgX (X=H, Li, Na, K, Rb, CH3, SiH3, GeH3, SnH3, NH2, PH2, AsH2, SbH2, OH, SH, SeH, TeH, O, S, Se, Te, F, Cl, Br, I, CN, CF3, OCF3) and their corresponding 28 cations is investigated. Mercury undergoes weak covalent bonding with its partner X in most cases (exceptions: X=alkali atoms, which lead to van der Waals bonding) although the BDEs are mostly smaller than 12 kcal mol−1. Bonding is weakened by 1) a singly occupied destabilized σ*‐HOMO and 2) lone pair repulsion. The magnitude of σ*‐destabilization can be determined from the energy difference BDE(HgX)−BDE(HgX+), which is largest for bonding partners from groups IVb and Vb of the periodic table (up to 80 kcal mol−1). BDEs can be enlarged by charge transfer from Hg and increased HgX ionic bonding, provided the bonding partner of Hg is sufficiently electronegative. The fine‐tuning of covalent and ionic bonding, σ‐destabilization, and lone‐pair repulsion occurs via relativistic effects where 6s AO contraction and 5d AO expansion are decisive. Lone pair repulsion involving the mercury 5d AOs plays an important role in the case of some mercury chalcogenides HgE (E=O, Te) where it leads to 3Π rather than 1Σ+ ground states. However, both HgE(3Π) and HgE(1Σ+) should not be experimentally detectable under normal conditions, which is in contrast to experimental predictions suggesting BDE values for HgE between 30 and 53 kcal mol−1. The results of this work are discussed with regard to their relevance for mercury bonding in general, the chemistry of mercury, and reactions of elemental Hg in the atmosphere.

Mössbauer spectroscopy for heavy elements: a relativistic benchmark study of mercury

“…We calculated the IP at the FS-CCSD[cv] correlation level using either the TZ or QZ basis sets. Our data of 232.0 kcal mol -1 and 233.2 kcal mol -1 , respectively, are in very good agreement with the IP of 235.3 kcal mol -1 reported by Cremer and co-workers [110] who derived their value from scalarrelativistic DFT calculations.…”

“…The HOMO-1 orbital has some contributions from Hg 5d which are, however, suppressed upon Pipek-Mezey localization [58,129] of the closedshell occupied orbitals, giving an orbital dominated by F 2p (78.1%), 2s (7.1%) and Hg 6s 1/2 (12.0%). We find only minor contributions from Hg 6p, contrary to the analysis of Schwerdtfeger et al [111], and the bonding corresponds rather to the three-electron two-orbital model discussed by Cremer et al [110]. These findings corroborate also our conclusions from the FS-CCSD calculations in Sect.…”

The CU ground MAX-DOAS instrument: characterization of RMS noise limitations and first measurements near Pensacola, FL of BrO, IO, and CHOCHO

“…Field studies (Peleg et al, 2007;Lindberg et al, 2002), laboratory studies (Donohoue et al, 2006), quantum calculations (Goodsite et al, 2004;Cremer et al, 2008;Balabanov et al, 2003;Tossell, 2003), and modeling studies (Holmes et al, 2006(Holmes et al, , 2009Selin et al, 2007) consistently suggest 2 Authors wish to note that the use of geometric AMFs for this calculation is a simplification of the radiative transfer process. We have carried out full radiative transfer calculations that varied in the assumptions about the BrO vertical distribution and find this simplification equally represents the uncertainty arising from the lack of knowledge about the true BrO vertical distribution aloft.…”

Darmstadtium, roentgenium, and copernicium form strong bonds with cyanide

“…The bond dissociation energy for HgCN (open shell, and 215.90 pm HgAC bond length) calculated using CCSD(T) by Cremer et al is 2.41 eV. [4] In our calculations for HgCN 1 (closed shell and a HgAC bond length of 198.31 pm), we got a BDE of 2.51 eV. Considering a 17.59 pm bond length difference between the complexes, this gives confidence that our calculated BDE for the complexes are accurate.…”

“…Heavy-element compounds have been rather extensively studied [1][2][3][4][5][6][7] compared to the superheavy ones. This is due to the abundance of the heavy elements and the many uses of heavy-element compounds; for instance, gold dicyanide (AuðCNÞ 2 2 ) was used in gold mining, [8,9] platinum cyanides are used in nanomaterials, [10] whereas mercury(II) cyanide (HgðCNÞ 2 ) was used as an antiseptic [11] until this was stopped due to its toxicity.…”