Transition Metal Complexes of Cyclic and Open Ozone and Thiozone

Abstract

Cyclic ozone (O3) has not been isolated so far, despite its computed kinetic persistence. Possibilities of "trapping" this molecule (or the valence-isoelectronic cyclic thiozone, S3) in transition metal complexes are investigated in this paper. Candidates were constructed, first using the 18-electron rule as a guide and then optimizing the structures with the DFT-B3LYP method. A variety of structures result: oxo-peroxo species, di-sigma- and pi-bonded open ozone complexes, some eta1 and eta2 cyclic ozone complexes, and a few bona fide eta3 cyclic O3 and S3 complexes. MLn fragments suitable for complex formation would need to contain very strong pi-acceptor ligands. Nitrosyl ligands were chosen to minimize an energy mismatch between the O3 donor orbitals and the MLn acceptor orbitals. On this basis, the existence of the complexes [S3W(NO)3]3+, [O3M(NO)3]3+ (M = Cr, Mo, W, Fe, Ru, Os), and [S3W(NO)2(CO)]2+ containing cyclic O3 and S3 is suggested. In another approach, facing up to the oxidizing power of O3, potential systems were built from late transition metals in high oxidation states, and also d0 early transition metal centers.

An exploration of the ozone dimer potential energy surface

“…However, while the unique properties of this molecule require high levels of theory, most of the previous work has been carried out at HF, MP2, or DFT (density functional theory) levels, which has limited their reliability. [6][7][8][9][10][11][12] The reproducibility between the theoretical and experimental results through the selection of adequate methodology is crucial in order to offer to the scientific community truly valid results. Otherwise, deficiencies become evident.…”

Learning from Molecules in Distress

“…But it has a substantial calculated barrier to falling apart into its open isomer, because that process is a forbidden reaction. [41] OCCO 15 is a dimer of carbon monoxide, and that would explain, it might seem, its non-existence. But hold on, it should have a triplet ground state, for the same reasons that O 2 has.…”

Encapsulation and convex‐face thiozonolysis of triatomic sulfur (S3) with carbon nanotubes

“…Except for SCF/DZ + P and M06-2X/cc-type, all calculations employed in Table 1 favor the C 2v form of S 3 to the D 3h form by 2.8 to 7.9 kcal/mol. [59][60][61][62][63][64][65] Reaching 2 from 1 is a high-barrier process (24.8 to 36.9 kcal/mol); as reported before, [66] the cyclization is symmetry forbidden attributed to the gain of a σ bond in 2 and the loss of a π bond in 1. Ruedenberg et al computed that the interconversion of 1 and 2 occurred via a C 2v transition state that lied in the vicinity of a conical intersection.…”