Predicting new, simple inorganic species by quantum chemical calculations: some successes

Abstract

A combination of ab initio calculations with the isoelectronic principle and chemical intuition is a useful way to predict new species. Some experimentally verified examples are (1) the transition-metal hydrides, MH(n) (n = 4-12), (2) new members of the multiply-bonded 2nd- or 3rd-period species A≡B, A=B=C, A=B=C=D or A≡B-C≡D, and A=B=C=D=E classes, the last-mentioned class including the cations N and OCNCO(+), (3) new members of the uranyl isoelectronic series, (4) actinyls where one of the oxygens is replaced by a 5d transition-metal (TM), (5) certain systems with noble-gas-noble-metal bonds, (6) the first argon compound HArF, (7) the cluster series of WAu(12), (8) TM-centred polyazide anions, (9) covalent molecules with a central -Zn-Zn- bond, (10) tetrahedral clusters of zinc and cadmium, (11) model systems for otherwise missing multiple bonds and (12) certain endohedral A@B systems. Further series of hypothetical species were used as a tool for developing recent sets of covalent radii, for studying the endohedral intermolecular interactions in A@B systems, or for finding examples of a 32-electron rule, corresponding to the well-known 8e- and 18e-rules. For obvious reasons, much of the molecular chemistry of the superheavy elements is based on studies of hypothetical model systems.

Theoretical chemistry of superheavy elements: Support for experiment

“…Atomic/ionic/covalent radii and polarizabilities of SHE are now also available at various levels of theory [2,6,7,14]. An important finding is smaller covalent radii of the 6d elements than those of the 5d ones in group 9 through 12, called a "transactinide break" [14,15].…”

“…An important finding is smaller covalent radii of the 6d elements than those of the 5d ones in group 9 through 12, called a "transactinide break" [14,15].…”

“…Some molecular species of even heavier elements are suggested in [14], whose stability may be proven by detailed calculations.…”

“…The proximity of the valence SO bands makes the search for the correct ground state very difficult. The usual classification on the basis of a simple electronic configuration and the placement of these elements in this part of the Periodic Table becomes, therefore, problematic, so that the shape of the table at these high Z is still under discussion and debate [3,14,15].…”

The Formal Oxidation States of Iridium Now Run from −III to +IX

“…[5,6] Indeed, for many new exotic species, prediction precedes production. [7] The 3 ] has been reported. [2] We observe that 9 + 3 + 6 = 18: This compound obeys the 18-electron rule.…”