.beta.-Hydride elimination for an amine ligand and the microscopic reverse: the first report of a cis-iminium hydride in equilibrium with its amine precursor

Osmium‐ and Rhenium‐Mediated Dearomatization Reactions with Arenes

“…The metal fragment is achiral and therefore cannot discriminate between enantiofaces upon binding. Unfortunately, changes to the ligand set about the metal completely nullify its ability to coordinate aromatic molecules [31]. Consequently, the achiral nature of the metal center as well as the electronic and steric properties of the system cannot be adjusted.…”

Complexes of Ruthenium and Osmium Containing η2–η6 Hydrocarbon Ligands: (i) Complexes not Containing Cyclobutadiene, Cyclopentadienyl or η-Arene Coligands

“…In contrast to (56), the C=O group o f which is bent 1 8° out of the ring plane, the C 5 R 4 O groups of (57)* are almost planar and the C-0 bond length (0.1286 nm) indicates a considerable resonance contribution f r o m the form C + -O~. The reversible dissociation o f (57) to the dicarbonyl (58) and the hydrido(r| 5 -cyclopentadienyl)complex (59) (Equation (14)) is the basic step in the reactions catalysed by (56); (59) Prolonged heating of (56), or of [Ru 3 (CO) 12 ] and tetracyclone, in dry heptane gives the dimer (60), which reacts readily with ligands (L) to form monomeric [Ru(CO) 2 (L)(r|-C 4 Ph 4 CO)] (L = CO, PPh 3 , PPh 2 H, P(OMe) 3 , BuNH 2 , PhNH 2 ). 144 ' 145 Amine complexes can also be obtained directly f r o m (56), for (66), not a T| 5 -complex.…”

“…The tetraphenylcyclopentadienone (tetracyclone) complex [Ru(CO) 3 (rj -C 4 Ph 4 CO)]* (56) is an excellent catalyst for the hydrogenation of alkenes and alkynes, for the dehydrogenative coupling o f alcohols to esters, for various hydrogen transfer reactions, and for alkyl group scrambling involving C-N bond cleavage in tertiary amines. It is one of the final products of catalyst transformation in Equation (12).…”

“…It is one of the final products of catalyst transformation in Equation (12). 141b In the presence of protic solvents, such as aqueous acetone, aqueous Na 2 CO 3 or n-propanol, (56) is converted into the dimeric species (57) (Equation (13)). 142 The x-ray structure o f the C 4 Ph 2 (C 6 H 4 Cl-/?)…”

Amine‐Activated Iron Catalysis: Air‐ and Moisture‐Stable Alkene and Alkyne Hydrofunctionalization

“…In order to further understand the mechanism of activation a series of stoichiometric reactions and NMR studies were carried out (see the Supporting Information for full details). Amines are well known to reduce 2 nd and 3 rd row transition metal species by coordination and β‐hydride elimination ,,. A limited number of examples have also been proposed for iron species ,,.…”