Functionalized N‑Heterocyclic Carbene Nonspectator Ligands upon Internal Alkyne Activation Reactions

• Published in: Inorganic chemistry 2013-06, Vol.52 (11), p.6502-6509
• Main Authors: Fernández, Francys E, Puerta, María del Carmen, Valerga, Pedro
• Format: Article
• Language: English
• Subjects: Alkynes - chemistry; Crystallography, X-Ray; Heterocyclic Compounds - chemistry; Ligands; Methane - analogs & derivatives; Methane - chemistry; Models, Molecular; Molecular Conformation; Organometallic Compounds - chemical synthesis; Organometallic Compounds - chemistry; Ruthenium - chemistry
• ISSN: 0020-1669; 1520-510X
• DOI: 10.1021/ic400433z

When studying the activation of 3-arylpropiolates by [TpRu(picolyl- R I)Cl]/NaBArF 4 (picolyl- Me I = 3-methyl-1-(2-picolyl)imidazol-2-ylidene (1); picolyl- Me BI = 3-methyl-1-(2-picolyl)benzoimidazol-2-ylidene (2)) a migratory insertion of the NHC into a ruthenium–carbon bond and an unprecedented C–N bond activation of the chelating picolyl-NHC ligand take place to give the new ruthenium metallacycles [TpRu(κ3-C,N,N′-C(Ph)C(CH2Py)(CO2Me)( Me I)][BArF 4] 3a and 4a and [TpRu(κ3-C,N,N′-C(4-CF3Ph)C(CH2Py)(CO2Me)( Me I)][BArF 4] 3b and 4b. X-ray crystal structures of 3a and 3b are reported, and a mechanistic pathway is proposed. In contrast, activation of internal alkynones by a mixture of [TpRu(picolyl- Me I)Cl] complex (1) and NaBArF 4 led to isolation and characterization of the corresponding disubstituted vinylidene complexes. Also, structures of [TpRu(picolyl- Me I)(CC(COR)(Ph)][BArF 4] (R = Me (6a); Ph (6b)) are reported.