107148-75-4Relevant academic research and scientific papers
Synthesis of [Ru2(CO) 5{1,2-bis(μ-alkylamido)-1,2-bis(2-pyridyl)ethane}] and [Ru2(CO)4{pyridine-2-carbaldehyde N-alkylimine}2] and the molecular structure of bis(pyridine-2-carbaldehyde N-isopropylimine)-tetracarbonyldiruthenium. Unprecedented CO-induced carbon-carbon bond formation ...
Polm, Louis H.,Elsevier, Cornelis J.,Van Koten, Gerard,Ernsting, Jan M.,Stufkens, Derk J.,Vrieze, Kees,Andréa, Ronald R.,Stam, Casper H.
, p. 1096 - 1104 (2008/10/08)
Full title: Synthesis of [Ru2(CO) 5{1,2-bis(μ-alkylamido)-1,2-bis(2-pyridyl)ethane}] and [Ru2(CO)4{pyridine-2-carbaldehyde N-alkylimine}2] and the molecular structure of bis(pyridine-2-carbaldehyde N-isopropylimine)-tetracarbonyldiruthenium. Unprecedented CO-induced carbon-carbon bond formation between two pyridine-2-carbaldimines in dinuclear ruthenium carbonyl complexes. Reaction of either Ru2(CO)6(R-Pyca{R1,R2}) with R-Pyca{R1,R2} (R-Pyca(R1,R2} = 6-R1C5H3N-2-C(R2)=NR; R = t-Bu, i-Pr, c-Hex; R1 = Me, H; R2 = H) or Ru3(CO)12 with R-Pyca{R1,R2} at 110°C in toluene yields Ru2(CO)5(R-APE{R1,R2}) (R-APE{R1,R2} = [6-R1C5H3N-2]C(R2)(NR)C(R 2)(NR)[2-C5H3N-6-R1]). The 10e donor ligand R-APE{R1,R2} arises from the carbon-carbon coupling of two R-Pyca{R1,R2} molecules. The product obtained after heating a xylene solution of either Ru2(CO)5(R-APE{R1,R2}) or Ru3(CO)12 with R-Pyca{R1,R2} at 140°C depends strongly on the substituent R1 at the 6-position of the pyridine ring. In the case that R1 = Me, one CO ligand per molecule is evolved and Ru2(CO)4(R-APE{Me,H}) possessing a 10e R-APE ligand and a Ru-Ru bond is obtained. However, when R1 = H, Ru2(CO)4(R-Pyca)2 is formed exclusively, as a result of CO elimination, selective carbon-carbon bond rupture, and breaking of the metal-metal bond. The structure of Ru2(CO)4(i-Pr-Pyca)2 was solved by X-ray structure determination. Crystals of C22H22N4O2Ru2 are monoclinic of space group P21/a with cell constants a = 10.976 (2) A?, b = 12.936 (2) A?, c = 8.881 (1) A?, β = 113.78 (1)°, and Z = 2. A total of 1514 reflections have been used in the refinement, which resulted in a final R value of 0.030 (Rw = 0.055). The Ru-Ru distance is 3.30 (1) A?. The molecule contains four terminal CO's and two i-Pr-Pyca ligands coordinated in the σ-N, μ2-N′, η2-C=N′ (6e) mode to the Ru2(CO)4 core. The torsion angle of 6° between the C(1)-N(1) and C(2)-N(2) bonds indicates that the planarity of the N=CC=N system of free R-Pyca is not affected much upon coordination. Ru2(CO)5(i-Pr-APE{R1,R2}) is formed efficiently by reaction of Ru2(CO)4(i-Pr-APE{Me,H}) or Ru2(CO)4(i-Pr-Pyca)2 with CO gas (1 atm) in toluene at 110°C. These reverse reactions imply addition of CO in the case of Ru2(CO)4(i-Pr-APE{Me,H}) and addition of CO concomitant with the formation of a carbon-carbon bond between the two imine carbon atoms of the two R-Pyca's in the case of Ru2-(CO)4(i-Pr-Pyca)2. The latter reaction is unprecedented. Possible mechanisms for the formation of Ru2(CO)5(R-APE{R1,R2}) from Ru2(CO)6(R-Pyca{R1,R2}) and for the reversible carbon-carbon bond formation/bond rupture reaction, Ru2(CO)4(R-Pyca)2 + CO ? Ru2(CO)5(R-APE), are discussed.
