Electron counting and bonding analysis in triruthenium clusters containing sulfoximido ligands: true or false electron-deficient systems?

Abstract

Triruthenium clusters containing a methylphenylsulfoximido cap or bridge, Ru 3 (CO) 9 analyze the bonding present in the clusters and to establish the electron counting. They clearly show that a m 3 -sulfoximido group is not a 3e − ligand as one may be led to think at first sight, but rather acts as a three-orbital/5e − system, i.e. should be considered as isolobal to an N R − ligand. Because of some delocalization of its p-type orbitals on the sulfur and oxygen atoms, it is expected to bind slightly less strongly to metal atoms than classical imido ligands. Once in a m 2 coordination mode, the sulfoximido ligand retains a lone pair on its pyramidalized N atom and becomes a two-orbital/3e − ligand. It follows that clusters 1, 2, 4 and 5 are electron-precise, whereas cluster 3 is electron deficient with respect to the 18e − rule but obeys the polyhedral skeletal electron pair electron-counting rules. Consistently, all the calculated clusters exhibit large HOMO-LUMO gaps and no trace of electron deficiency can be found in their electronic structures.

Can μ4-Alkyne and μ3-Alkenyl Ligands Be Considered as Six- and Five-Electron Donors, Respectively?

“…It has also been reported that the EHMO-computed HOMO−LUMO gap of the alkenyl cluster [Ru 3 {μ 3 -NS(O)H 2 }(μ 3 -CHCH 2 )(μ-CO)(CO) 7 ], a simplified model of complex 8 (Chart ), is large (2.01 eV), but the authors of that work do not mention which FMOs of the alkenyl fragment are involved in the bonding of this ligand with the metal atoms …”

Electron‐Deficient Triruthenium Clusters Containing Small Bite‐Angle PNP‐Ligands

“…Beside compound 1, only few 46e Ru 3 species were reported in the literature. [4][5][6][7][8][9] Compound 1 was obtained by the reaction of [Ru 3 (CO) 10 (μ-dppm)] with the secondary phosphane PtBu 2 H, whereas in the first step of the reaction the species [Ru 3 (CO) 9 (μ-dppm)(PtBu t 2 H)] could be detected and isolated (also shown for P(1-Ad) 2 H and PCy 2 H). [2] Currently we are interested to examine that reaction behavior of secondary phosphanes in the related system [Ru 3 (CO) 10 (μ-dppa)] [10,11] and N-substituted derivatives of dppa respectively.…”

Mixed-Metal Cluster Chemistry. 19. Crystallographic, Spectroscopic, Electrochemical, Spectroelectrochemical, and Theoretical Studies of Systematically Varied Tetrahedral Group 6−Iridium Clusters

“…Studies of cluster electrochemistry, − carried out frequently in concert with electronic structure calculations, − have afforded information about the highest occupied molecular orbitals (HOMOs) and lowest unoccupied molecular orbitals (LUMOs). Calculations using density functional theory have been promulgated to enhance understanding of spectroscopic properties, charge distributions, and reactivities. ,− Cluster electrochemistry, in combination with IR and UV−visible spectroelectrochemistry and frequently EPR, has afforded insight into the electronic and molecular structure of clusters in varying oxidation states. ,− …”