Novel Dinuclear (μ-Hydrido)(μ-alkylideneamido)ruthenium Complexes, [(η⁵-C₅Me₅)Ru]₂(μ-L)(μ-H)(μ-NCHR) (R = Me, Et; L = MeCN, Arene), as Precursors of Active Species for Bimetallic Activation. Dehydrogenative Coupling of Ethylene in a Dinuclear Ruthenium Complex

Abstract

The dinuclear ruthenium tetrahydride [(η5-C5Me5)Ru(μ-H)2]2 reacts with acetonitrile or propionitrile in the presence of an arene such as toluene or naphthalene to generate the (μ-hydrido)(μ-alkylideneamido)ruthenium complex (Cp‘Ru)2(μ-L)(μ-H)(μ-NCHR) (L = (arene); Cp‘ = η5-C5Me5). The reaction of the (μ-alkylideneamido)ruthenium complex with ethylene gives the bis(ethylene)ruthenium complex [Cp‘Ru(η2-CH2CH2)]2(μ-H)(μ-NCHCH3), which undergoes dehydrogenative coupling of the ethylene ligand to yield the μ-η2:η2-s-cis-butadiene complex (Cp‘Ru)2(μ-η2:η2-CH2CHCHCH2)(μ-H)(μ-NCHCH3).

Activation of Organic Substrates on Multi-Metallic Sites of Transition Metal Polyhydride Clusters Having C5Me5 Groups as Auxiliary Ligands

“…[13] The coordinated nitrile molecule in 3 was readily replaced with arene to form an (alkylideneamide)(η 2 :η 2 -arene) complex {(C 5 Me 5 )Ru} 2 (µ-η 2 :η 2 -arene)(µ-NϭCHR) (4). Complex 4 was directly synthesized by the reaction of 1 with nitrile in an appropriate arene solution.…”

“…A new class of trinuclear polyhydride cluster with a triply bridging ligand has therefore been synthesized by using pentahydride 12 as the starting material. (9) Cluster 12 was converted into a mono-µ 3 -oxo complex {(C 5 Me 5 )Ru} 3 (µ 3 -O)(µ-H) 3 (13) and a di-µ 3 -oxo complex {(C 5 Me 5 )Ru} 3 (µ 3 -O) 2 (µ-H) (14), successively, by the reaction with dioxygen at low temperature [Equation (9)]. [29] The mono-µ 3 -oxo complex was isolated in high yield by controlling the reaction conditions such as the O 2 /12 ratio and the temperature.…”

“…The reaction of 4 with 1 atm of ethylene proceeded at ambient temperature to give a bis(η 2 -ethylene)ruthenium complex 24. [13] When 24 was heated at 80°C, a µ-η 2 :η 2 -s-cis-butadiene complex 25 was exclusively formed by a dehydrogenative coupling of the coordinated ethylene molecule (Scheme 7).…”

Intramolecular Double C-H Activation in FvM2(en)4(Fv=fulvalene; M=Ir, Rh; en=ethylene)

“…This photochemical reaction was performed in 1.5 mM solution of the reactant in degassed dry benzene by a broad-band Hanovia 450 W medium Hg-vapor lamp with a water-cooled jacket (Scheme 4). 14,21,22,23 In this report, we reveal the first sytheses of FvIr 2 (en) 4 (12) 15 and FvRh(en) 4 valene was then introduced into the reaction solution at 0 o C with ethylene bubbling for more than 1hr, leading to a deep orange precipitation. This product solution was passed through Celite column and solvent was removed under vacuum.…”

“…4 In particular, dinuclear organotransition-metal have gained much attention seemingly due to the fact that bimetallic compounds incorporating two reactive metal sites in close proximity may be in easy access to reaction pathways not available to mononuclear systems as a result of mutually beneficial electronic and/or steric effects. However, it seems extremely of import to avoid fragmentation of the polynuclear framework so as to achieve true reactivity.…”