Hydrogénation of phosphido bridged ruthenium clusters. A view of P—C bond activation and cleavage in the coordinatively unsaturated molecule Ru₃(CO)₉(μ₂-PPh₂)(μ₂-H): conversion of μ₂-PPh₂ to μ₃-PPh

Abstract

Treatment of Ru3(CO)8(μ3-η2-C≡CR)(μ2-PPh2)(R = But, Pri) with dihydrogen liberates olefin (CH2=CHR) and generates the coordinatively unsaturated cluster Ru3(CO)9(μ2-PPh2)(μ2-H) which has been shown by X-ray diffraction to have an unprecedented μ2-phosphido bridge in which a P—phenyl group interacts with an electron deficient ruthenium atom. This molecule provides an insight into P—C bond activation leading to cleavage. Further reaction of Ru3(CO)9(μ2-PPh2)(μ2-H) with H2 leads to the phosphinidene cluster Ru3(CO)9(μ3-PPh)(μ2-H)2 via elimination of benzene. Conversion of Ru3(CO)9(μ2-PPh2)(μ2-H) to another phosphinidene cluster Ru4(CO)13(μ3-PPh) occurs on pyrolysis. Hydrogénation of multi-site bound acetylides with H2 is a potentially useful synthetic route to unsaturated clusters. Hydrogenative conversion of μ2-PPh2 to μ3-PPh groups has significance for the synthesis of phosphinidene capped molecules as well as the chemistry of phosphido bridged clusters.

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

“…We first investigate the C s model {Ru 3 (CO) 9 [m 3 -NS(O)H 2 ]} − , which is derived from 1 by deprotonation and substitution of the Ph and Me groups of the sulfoximido ligand by H atoms. The MO diagram of this model is shown in Fig.…”

“…The MO diagram of this model is shown in Fig. 2, based on the interaction of the Ru 3 (CO) 9 and [NS(O)H 2 ] − fragments (fragment charges are formal).…”

“…We therefore introduced the chiral methylphenylsulfoximido ligand into the trinuclear ruthenium system by reaction of Ru 3 (CO) 12 with MePhS(O)NH. The only high-yield product of this reaction, Ru 3 (CO) 9 (m 2 -H)[m 3 -NS(O)MePh] (1, Eq. (1)), which we isolated in both enantiomeric forms and characterized by single-crystal X-ray crystallography, was considered to be an electron-deficient 46e − cluster (taking into account the sulfoximido cap as a 3e − ligand [2].…”

“…is obtained [6], whereas PhC C-p-C 6 H 4 NO 2 reacts with carbon -carbon coupling to give the clusters Ru 3 (CO) 9 [7]. Counting the NS(O)MePh ligand as a 3e − donor, 3 was considered as a 46e − cluster (the ligand PhC CHBu being a 3e − donor), 4 as a 50e − cluster (the ligand PhC C C CHPh being a 5e − donor), and 5 as a 48e − cluster (the ligand PhC+ C C CHPh being a 5e − donor).…”

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AbstractTriruthenium 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.

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