The reactions of the NHC-functionalized phosphines 1-[{2-(diphenylphosphino)­phenyl}­methyl]-3-methylimidazol-2-ylidene (Ph2PC6H4CH2ImMe) and 1-[{2-(dicyclohexylphosphino)­phenyl}­methyl]-3-methylimidazol-2-ylidene (Cy2PC6H4CH2ImMe) and the NHC-functionalized thioether 1-{(2-methylsulfide)­ethyl}-3-methylimidazol-2-ylidene (MeSCH2CH2ImMe) with [Ru3(CO)12] have been studied. Both NHC-phosphines react with equimolar amounts of [Ru3(CO)12], in THF at room temperature, to give the edge-bridged disubstituted products [Ru3(μ-κ2 P,C NHC-R2PC6H4CH2ImMe)­(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 [Ru3(μ-H)2(μ3-κ3 P,C,C NHC-R2PC6H4CImMe)­(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 [Ru3(CO)12] with 3 equivalents of Ph2PC6H4CH2ImMe leads to the mononuclear ruthenium(0) complex [Ru­(κ2 P,C NHC-Ph2PC6H4CH2ImMe)­(CO)3] (5). No trinuclear derivatives were obtained from reactions of [Ru3(CO)12] with MeSCH2CH2ImMe, the tetranuclear derivative [Ru4(μ-κ2 S,C NHC-MeSCH2CH2ImMe)­(μ-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.

The trinuclear cluster [Ru 3 (CO) 12 ] reacts at room temperature with the phosphine-functionalized N-heterocyclic carbene (NHC) ligand 1-[2-(diphenylphophino)ethyl]-3-methylimidazol-2-ylidene (dppeImMe), in 1:1 mol ratio, to give the edge-bridged trinuclear derivative [Ru 3 (μ-κ 2 C,P-dppeImMe)(CO) 10 ] (1). The use of a 1:3 [Ru 3 (CO) 12 ] to dppeImMe mol ratio leads to the mononuclear derivative [Ru(κ 2 C,P-dppeImMe)(CO) 3 ] (2), which has a trigonal-bipyramidal ligand arrangement with the NHC and phosphine fragments of the dppeImMe ligand in axial and equatorial positions, respectively. Upon gentle heating (refluxing THF), compound 1 is transformed into the face-capped dihydrido derivative [Ru 3 (μ-H) 2 (μ 3 -κ 3 C 2 ,P-dppeImCH)(CO) 8 ] (3), which arises from the oxidative addition of two C-H bonds of the N-methyl group of the dppeImMe ligand. The trinuclear salt [Ru 3 (κP-dppeHImMe) on each Ru atom, has been prepared by treating [Ru 3 (CO) 12 ] with the salt [dppeHImMe][BF 4 ]. The deprotonation of 4[BF 4 ] 3 with three equivalents of K[N(SiMe 3 ) 2 ] is an alternative way to prepare the mononuclear complex 2.

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The high basicity of a trimethylene-linked bis(NHC), acting as a chelating ligand in a ruthenium(0) complex, is responsible for its involvement in a room-temperature reaction in which the metal atom to which this bis(NHC) ligand is coordinated replaces a hydride anion of the ligand trimethylene linker, which can be taken by a hydride abstractor as unusual, in that role, as [Ru3(CO)12].