Rare and Nonexistent Nitrosyls: Periodic Trends and Relativistic Effects in Ruthenium and Osmium Porphyrin-Based {MNO}⁷ Complexes

Abstract

Relativistic and nonrelativistic density functional theory calculations were used to investigate rare or nonexistent ruthenium and osmium analogues of nitrosylhemes. Strong ligand field effects and, to a lesser degree, relativistic effects were found to destabilize {RuNO} 7 porphyrins relative to their {FeNO} 7 analogues. Substantially stronger relativistic effects account for the even greater instability and/or nonexistence of {OsNO} 7 porphyrin derivatives.

Porphyryne

“…As powerful Diels–Alder dienophiles, benzynes and other arynes are widely employed as highly reactive synthetic reagents and intermediates. − Benzynes are key intermediates of the hexadehydro-Diels–Alder reaction, a synthetic reaction recently developed by Hoye and coworkers. , Interestingly, in spite of major advances in the functionalization of porphyrin-type compounds, − an aryne based on a porphyrin, i.e., a porphyryne, remains unknown. Herein, following a long-standing tradition among chemical theoreticians in studying reasonable-looking but nonexistent molecules, − we have considered the viability of such an intermediate based on a comparative density functional theory (DFT) study of zinc porphyryne and benzyne.…”

Relativity as a Synthesis Design Principle: A Comparative Study of [3 + 2] Cycloaddition of Technetium(VII) and Rhenium(VII) Trioxo Complexes with Olefins

“…Indeed, in 1929, Paul Dirac asserted that the only imperfections remaining in quantum mechanics “give rise to difficulties only when high-speed particles are involved, and are therefore of no importance in the consideration of atomic and molecular structure and ordinary chemical reactions in which it is, indeed, usually sufficiently accurate if one neglects relativity variation of mass and velocity and assumes only Coulomb forces between the various electrons and atomic nuclei.” This view started changing only in the 1970s. , Today the importance of relativistic effects is well recognized for the static properties of sixth- and seventh-period elements . Relativity thus accounts for such well-known effects as the liquid state of Hg and the yellow color of elemental Au and Cs as well as a host of less well-known effects in heavy-element chemistry. − …”

Relativistic Effects on a Metal–Metal Bond: Osmium Corrole Dimers

“…Under these conditions, i.e., P expt = P nrel , we may with some justification speak about the relativistic effect on an experimentally determined property P expt or, more briefly, an experimentally calibrated relativistic effect. Fortunately, density functional theory (DFT) often provides both a computationally expedient and a surprisingly accurate description of relativistic effects on heavy element compounds. − …”