DFT Investigation of the Mechanism of Phosphine-Thioether Isomerization in the Triosmium Cluster Os-3(CO)(10)(Ph2PCH2CH2SMe): Migratory Preference for the Formation of an Edge-Bridged Thioether versus a Phosphine Moiety

Summary, in English

The rearrangement of the phosphine-thioether ligand in 1,2-(P-eq,S-eq)-Os-3(CO)(10)(Ph2PCH2CH2SMe) to 1,1-(P-eq,S-ax)-Os-3(CO)(10)(Ph2PCH2CH2SMe) was investigated by electronic structure calculations. The chelated isomer lies 2.5 kcal/mol lower in energy than its bridged counterpart, and the barrier computed for the mechanism is in agreement with the results from our earlier experimental study. Phosphine-thioether isomerization occurs via three distinct steps that involve the migration of the CO and SMe groups in a plane that is perpendicular to the trimetallic core. One of the intermediates on the reaction surface corresponds to the 50e cluster Os-3(CO)(9)(mu-CO)(mu-Ph2PCH2CH2SMe), whose edge-bridging thioether moiety functions as a 4e donor ligand. Alternative mechanisms involving ligand dissociation/association and merry-go-round sequences are energetically prohibitive.

• Author: David A. Hrovat; Ebbe Nordlander; Michael G. Richmond
• Department/s: Chemical Physics
• Publishing year: 2012
• Language: English
• Pages: 6608-6613
• Publication/Series: Organometallics
• Volume: 31
• Issue: 18
• Links: http://dx.doi.org/10.1021/om300640t
• Document type: Journal article
• Publisher: The American Chemical Society (ACS)
• Topic: Atom and Molecular Physics and Optics
• Status: Published
• ISBN/ISSN/Other: ISSN: 1520-6041