An 18-Electron System Containing a Superheavy Element: Theoretical Studies of Sg@Au₁₂

Abstract

M@Au12 cage molecules (M = transition element from group 6) are interesting clusters with high-symmetric structure and significant stability. As the heavier homologue of W is (106)Sg, it is interesting to pinpoint whether the Sg@Au12 cluster is also stable. Geometric and electronic structures and bonding of various Sg@Au12 isomers were investigated with density functional theory (PW91, PBE, B3LYP) and wave function theory (MP2, CCSD(T)) approaches. The lowest-energy isomer of Sg@Au12 has icosahedral symmetry with significant Sg(6d)-Au(6s) covalent-metallic interaction and is comparable to the lighter homologues (M = Mo, W), with similar binding energy, although Sg follows (as a rare case) the textbook rule "ns below (n - 1)d". The 12 6s valence electrons from Au12 and the six 7s6d ones from Sg can be viewed as an 18e system below and above the interacting Au 5d band, forming nine delocalized multicenter bond pairs with a high stability of ∼0.8 eV of bond energy per each of the 12 Sg-Au contacts. Different prescriptions (orbital, multipole-deformation, charge-partition, and X-ray-spectroscopy based ones) assign ambiguous atomic charges to the centric and peripheral atoms; atomic core-level energy shifts correspond to some negative charge shift to the gold periphery, more so for Cr@Au12 than for Sg@Au12 or Au@Au12.

Decomposition studies of group 6 hexacarbonyl complexes. Part 2: Modelling of the decomposition process

“…The influence of the principles of relativity on the chemical behavior of element Sg has recently observed a revival of interest [13,14]. Particularly, in [13] a class of cage-compounds of group 6 elements with gold is discussed where the group 6 elements are in zeroth oxidation state leading to an 18 electron system similar to the hexacarbonyl complex.…”

“…Particularly, in [13] a class of cage-compounds of group 6 elements with gold is discussed where the group 6 elements are in zeroth oxidation state leading to an 18 electron system similar to the hexacarbonyl complex. The calculated binding energies in the M-Au cluster revealed small differences along the group 6 following the order Mo ≤ W > Sg.…”

“…The calculated binding energies in the M-Au cluster revealed small differences along the group 6 following the order Mo ≤ W > Sg. The effective atomic radii of the central transition metal atoms, connected to the electron density distributions of the and orbitals, are determining the binding in such compounds [13]. The radial expansion of the d-orbitals is predicted to slightly increase with the atomic number among these elements [14].…”

“…The radial expansion of the d-orbitals is predicted to slightly increase with the atomic number among these elements [14]. Remarkably, strong relativistic effects point to a Sg(7s) valence orbital level, energetically shifted below the Sg(6d) level [13] …”

A first-principles study on the B5O5+/0 and B5O5− clusters: The boron oxide analogs of C6H5+/0 and CH3Cl

“…S5(c)). [60][61][62] This is markedly different from other B centers, which carry positive charges (+0.9 to +1.2|e|). Additional negative charge is distributed on the OBO unit, whereas the BO groups are practically neutral.…”