199527-95-2Relevant academic research and scientific papers
Addition of carbon nucleophiles to the allenylidene ligand of [Ru(η5-C5H5)(C=C=CPh2) (CO) (PiPr3)]BF4: Synthesis of new organic ligands by formal C-C coupling between mutually inert fragments
Esteruelas, Miguel A.,Gómez, Angel V.,López, Ana M.,Modrego, Javier,O?ate, Enrique
, p. 5826 - 5835 (2008/10/08)
EHT-MO Calculations on the model cation [Ru(η5-C5H5)(C=C=CH 2)(CO)(PH3)]+ (1a) suggest that 23% and 31% of the LUMO and 26% of the HOMO of [Ru(η5-C5H5)(C=C=CPh 2)-(CO)(PiPr3)]BF4 (1) are located on Cα, Cγ, and Cβ of the allenylidene ligand, respectively. On the basis of these results, we report a new synthetic strategy for the preparation of compounds resulting from the formal addition of phenylacetylene, acetone, and methane to the allenylidene of 1. Treatment of 1 with LiC≡CPh leads to the allenyl complex Ru(η5-C5H5){C(C=CPh)=C=CPh 2}(CO)(PiPr3) (2) and the alkynyl derivative Ru(η5-C5H5){C≡C-C(Ph) 2C≡CPh}(CO)(PiPr3) (3). The reaction of 2 with HBF4 affords the substituted carbene compound [Ru(η5-C5H5){C(C≡CPh)CH=CPh 2}(CO)(PiPr3)]BF4 (4), which is a result from the formal addition of phenylacetylene to the Cα-Cβ double bond of the allenylidene of 1. The molecular structure of 4 has been determined by X-ray crystallography. The geometry around the ruthenium center is close to octahedral with the cyclopentadienyl ligand occupying three sites of a face. The Ru=C bond length is 2.004(5) A?. In the presence of KOH, complex 1 reacts with acetone to give Ru(η5-C5H5){C≡C-C(Ph) 2CH2C(O)CH3}(CO)(PiPr3) (5). The reaction of 5 with HBF4 leads to the unsaturated cyclic carbene complex [Ru(η5-C5H5)-{CCH2C(Ph) 2CH=C(CH3)O}(CO)(PiPr3)]BF 4 (6). Complex 5 also reacts with 2 equiv of CF3-CO2D to give [Ru(η5-C5H5){CCD2C(Ph) 2CH=C(CH3)O}(CO)(PiPr3)](CF 3CO2) (6-d2) and CF3-CO2H, and the reaction of Ru(η5-C5H5){C≡C-C(Ph) 2CD2C(O)CD3}(CO)(PiPr3) (5-d5) with 2 equiv of HBF4 affords [Ru(η5-C5H5){CCH2C(Ph) 2CD=C(CD3)6}(CO)(PiPr3)]BF 4 (6-d4) and DBF4. On the basis of these isotope labeling experiments, the mechanism for the addition of acetone to the allenylidene ligand of 1 is discussed. Complex 1 also reacts with Na-(acac) and CH3Li. The reaction with Na(acac) leads to Ru(η5-C5H5){C≡C-C(Ph) 2CH[C(O)-CH3]2}(CO)(PiPr 3) (7), while the treatment of 1 with CH3Li gives a mixture of Ru(η5-C5H5){C(CH3)=C=CPh 2}(CO)(PiPr3) (8) and Ru(η5-C5H5){C≡C-C(Ph) 2CH3}(CO)(PiPr3) (9). Complex 9 reacts with HBF4 to afford [Ru(η5-C5H5){C=CHC(Ph)2CH 3}(CO)(PiPr3)]BF4 (10), which is a result of the formal addition of a C-H bond of methane to the Cβ-Cγ double bond of the allenylidene of 1.
