C−C and C−H Bond Activation Reactions in N-Heterocyclic Carbene Complexes of Ruthenium

Abstract

Thermolysis of Ru(PPh3)3(CO)H2 with the N-heterocyclic carbene bis(1,3-(2,4,6-trimethylphenyl)imidazol-2-ylidene) (IMes) results in C-C activation of an Ar-CH3 bond in one of the mesityl rings of the carbene ligand. Upon addition of IMes to Ru(PPh3)3(CO)H2 at room temperature in the presence of an alkene, C-H bond activation is observed instead. The thermodynamics of these C-C and C-H cleavage reactions have been probed using density functional theory.

C–C σ complexes of rhodium

“…As required, characteristics of the critical points located In the AIM analysis of 4-Intd (Fig. 2b), four Rh-C bonds are located [Rh-C(11)/C(15)/C(21)/C(25)], and the corresponding BCPs (8,9,14,15) An energy diagram for complexes 4 and 4-Intd is provided in Fig. 3.…”

C–H vs. N–H Bond Activation in Aminophosphane Ligands: Reaction of [Cp*Ru(MeCN)2(PR12NHR2)]+ (R1 = Ph, iPr; R2 = Ph, C6F5) with Alkynes

“…Orthometalation processes at coordinatively unsaturated metal centers leading to hydrido-phenyl species have been well documented in the literature. [11][12][13][14] We also carried out reactions of 1, 2, and 3 with several olefins. The only characterized product from these reactions was the η + is shown in Figure 5, together with a listing of selected bond lengths and angles.…”

Reversible CH Bond Activation Reactions of the N‐Heterocyclic Carbene Ligands in Ru(Ph2PCH2CH2CH2PPh2)(IMes)(CO)H2 and Ru(Ph2AsCH2CH2PPh2)(IMes)(CO)H2 (IMes=1,3‐Dimesityl‐1,3‐dihydro‐2H‐imidazol‐2‐ylidene)

“…We have recently reported the first example of C À C bond activation of an NHC, starting from the biscarbene ruthenium complex Ru(IMes) 2 (PPh 3 )-(CO)H 2 . [9] We also showed that treatment of the mono-carbene species Ru(IMes)(PPh 3 ) 2 (CO)H 2 with CH 2 CHSiMe 3 , at room temperature, results in facile intramolecular C À H activation of an ortho-methyl group on the IMes ligand. To investigate the influence of the ancillary ligands on this process, we have prepared bidentate phosphine and phosphine-arsine precursors, which still exhibit C À H activation chemistry, albeit at higher temperatures.…”

“…The structure is severely bent around the C(2) ± Ru(1) ± P(2) axis [159.73(5)8], which in part reflects the phosphine bulk. A comparison of the structure of 2 with that of Ru(IMes×)(PPh 3 ) 2 (CO)H [9] indicates that there is alteration in the orientation of the C À H activated rings between the two structures, probably due to the variation in bulk of dppp relative to PPh 3 . This effect is clearly manifested in the C(22) ± Ru(1) ± P(1) angle [93.38(5)8] which compares with the corresponding C À Ru À P angle of 101.…”