Reactivity of phosphine- and thioether-tethered N-heterocyclic carbenes with ruthenium carbonyl

Cabeza, Javier A. and Damonte, Marina and Garcia-Alvarez, Pablo and Guadalupe Hernandez-Cruz, M. and Kennedy, Alan (2012) Reactivity of phosphine- and thioether-tethered N-heterocyclic carbenes with ruthenium carbonyl. Organometallics, 31 (1). pp. 327-334. ISSN 0276-7333 (https://doi.org/10.1021/om200954w)

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Abstract

The reactions of the NHC-functionalized phosphines 1-[{2-(diphenylphosphino)phenyl}methyl]-3-methylimidazol-2-ylidene (Ph(2)PC(6)H(4)CH(2)ImMe) and 1-[{2-(dicyclohexylphosphino)phenyl}methyl}-3-methylimidazol-2-ylidene (Cy(2)PC(6)H(4)CH(2)ImMe) and the NHC-functionalized thioether 1-{(2-methylsulfide)ethyl}-3-methylimidazol-2-ylidene (MeSCH(2)CH(2)ImMe) with [Ru-3(CO)(12)] have been studied. Both NHC-phosphines react with equimolar amounts of [Ru-3(CO)(12)], in THF at room temperature, to give the edge-bridged disubstituted products [Ru-3(mu-kappa P-2,C-NHC-R(2)PC(6)H(4)CH(2)ImMe)(CO)(10)}, R = Ph (1), Cy (2), which selectively undergo a double C-H bond activation of their CH2 group upon gentle warming (R = Ph) or at room temperature (R = Cy) to give the dihydrido derivatives [Ru-3(mu-H)(2)(mu(3)-kappa P-3,C,C-NHC-R(2)PC(6)H(4)CImMe)(CO)(8)}, R = Ph (3) and Cy (4), respectively. These products contain novel face-capping ligands that arise from the oxidative addition of both C H bonds of the corresponding NHC-phosphine ligand CH2 group. This double-metalation process is facilitated by the rigidity of the C6H4CH2 linker of these ligands. The treatment of [Ru-3(CO)(12)] with 3 equivalents of Ph(2)PC(6)H(4)CH(2)ImMe leads to the mononuclear ruthenium(0) complex [Ru(kappa P-2,C(NHC)Ph(2)PC(6)H(4)CH(2)ImMe)(CO)(3)} (5). No trinuclear derivatives were obtained from reactions of [Ru-3(CO)(12)] with MeSCH(2)CH(2)ImMe, the tetranuclear derivative [Ru-4(mu-kappa S-2,C-NHC-MeSCH(2)CH(2)ImMe)(mu-CO)(2)(CO)(10)) (6) being the only product that could be isolated. Compound 6 contains a butterfly arrangement of the metal atoms with the wing tips bridged by the ligand sulfur atom, while the NHC fragment is attached to one wing tip.

ORCID iDs

Cabeza, Javier A., Damonte, Marina, Garcia-Alvarez, Pablo, Guadalupe Hernandez-Cruz, M. and Kennedy, Alan ORCID logoORCID: https://orcid.org/0000-0003-3652-6015;