81432-45-3

Upstream product

• 15243-33-1 dodecacarbonyl-triangulo-triruthenium 

Downstream Products

• 178987-17-2 [N(PPh3)2][Ru2(CO)4(μ2-η(2)-CO2CH3)2(μ2-OCH3)I2] 

Relevant academic research and scientific papers

Promoter effect of chloride ions on the ruthenium-catalyzed hydroesterification of ethylene with methyl formate. Design and evaluation of new poly- and mononuclear catalyst precursors

The catalytic hydroesterification of ethylene with methyl formate to produce methyl propionate is shown to take place in the presence of trinuclear ruthenium carbonyl complexes modified by anionic nucleophiles such as amido (anilinopyridyl), alkoxy (pyridonate), or halide ligands, regarded as potential promoters. The best results (100% conversion, 99% selectivity) are obtained with the mixture Ru3(CO)12 + [PPN]Cl (1/1) under the following experimental conditions: [HCOOMe]/[cat.] = 345, DMF solvent, P(C2H4) = 20 atm (at 25°C), T = 160°C, time = 12 h. The complex [PPN][Ru3(μ3-Cl)(CO)9] (3) resulting from the addition of [PPN]-Cl to Ru3(CO)12 reacts cleanly with an excess of [PPN]Cl in refluxing THF under a stream of inert gas to produce the unique dianionic species [PPN]2[Ru4(μ-Cl)2(CO)11] (4) (70% yield). The X-ray structure analysis of 4 is reported (triclinic P1, No. 2, a = 18.209(2) A?, b = 18.877-(3) A?, c = 13.895(2) A?, α = 110.70(1)°, β = 108.43(1)°, γ = 87.43(1)°, V = 4226(1) A?3, Z = 2, R = 0.053, Rw = 0.069). The dianionic tetranuclear unit of 4 consists of a basic triangular metal framework Ru3(CO)9 one face of which is supported by a spiked Ru(CO)2Cl2 fragment involving a 16e metal center exhibiting a square pyramidal geometry. Extended Hu?ckel MO calculations indicate a large HOMO/LUMO gap (1.45 eV). Facile loss of Cl- from the above dianion is induced by capture of CO, leading to the known butterfly complex [PPN][Ru4(μ-Cl)(CO)13] (5). Complex 4 also reacts with O2 at 25°C to provide the new oxo derivative [PPN]2[Ru4(μ4-O)(μ-Cl) 4(CO)10] (6). The structure of 6 has been determined by X-ray diffraction (triclinic P1, No. 2, a = 13.226(5) A?, b = 25.533(2) A?, c = 12.771(3) A?, α = 92.39(1)°, β = 114.77(3)°, γ = 85.92(2)°, V = 3906(2) A?3, Z = 2, R = 0.038, Rw = 0.045). Its dianionic unit consists of a distorted quadratic antiprism based on two rectangular faces Ru(μ-Cl)2Ru and containing an encapsulated oxygen atom linked to the four ruthenium centers. The anionic complexes 4-6 also act as catalyst precursors for the hydroesterification reaction. Analysis of the solutions recovered at the end of all catalytic runs indicate the presence of [PPN]2[Ru6(C)(CO)16] as the principal metal-containing derivative. The probable mononuclear nature of the active species is suggested. A detailed investigation of the catalytic system based on [PPN][Ru(CO)3Cl3] (7) (prepared here in 81% yield by a new one-pot procedure) is reported. The results show that catalysis in the presence of the latter complex takes place readily without an induction period. Furthermore, a comparative evaluation of the four salts 7, [PPN][Ru(CO)3I3] (8), [PPN][Ru(CO)3Cl2I] (9), and [PPN][Ru(CO)3-ClI2] (10) as catalyst precursors reveals that chloride is a better promoter than iodide under the experimental conditions defined above, using DMF (or related amides) as solvent. Catalysis in the presence of 7 (and 3 equiv of NEt3 as cocatalyst) is complete within 2 h (100% conversion and 99% selectivity; overall turnover frequency = 170 h-1, corresponding to an initial activity of the order of 700 h-1). Complex 7 is seen to react readily with DMF at 160°C within 30 min to produce the new complex [PPN][Ru(CO)2Cl3(η1-DMF)] (11), isolated in 60% yield. The X-ray structure of 11 is reported (monoclinic P21/c, a = 9.000(2) A?, b = 21.176(2) A?, c = 21.080(1) A?, β = 93.89(8)°, V = 4008.3(9) A?3, Z = 4, R = 0.028, Rw = 0.030). The three chloride ligands adopt a meridional arrangement, whereas the DMF ligand, bound via its oxygen atom, occupies one of the two apical sites.

Equilibria within the Ru3(CO)12/halide system

The results reported herein, when combined with those from earlier studies, present a comprehensive picture of the various equilibria that exist in Ru3(CO)12 solutions containing halide ions, A remarkable number of complexes have been found to form and interconvert, with the position of the equilibria dependent upon temperature, the CO partial pressure, and the specific halide employed. All experiments described herein have used the [(Ph3P)2N]+ halide salts, except as noted. As previously noted by Kaesz and co-workers, Ru3(CO)12 rapidly reacts with Cl- and Br- ions to initially form the clusters [Ru3(X)(CO)11]- (2a,b), which reversibly lose CO to produce the species [Ru3(μ2-X)(CO)10]- (3a,b). The reaction of Ru3(CO)12 with iodide proceeds immediately to form [Ru3(μ2-I)(CO)10]- (3c) but with no evidence for the intermediacy of a cluster analogous to 2a and 2b. Clusters 3a and 3b rapidly add CO at 1 atm to form 2a and 2b, but cluster 3c does not take up CO under these mild conditions. When heated, the trinuclear clusters 3a-c all lose CO to transform reversibly into other species, but with the final product dependent upon the halide. The chloro and bromo derivatives 3a and 3b form the tetranuclear butterfly clusters [Ru4(μ2-X)(CO)13]- (6a and 6b), along with 1/4 equiv of halide ion, and these reactions are cleanly reversed by placing 6a and 6b with the necessary halide under 1 atm of CO. The iodo cluster 3c loses CO upon heating to form the trinuclear species [Ru3(μ3-I)(CO)9]- (7c), which has been crystallographically defined as the [Na(18-crown-6)]+ salt: space group Pnma, a = 20.214 (5) A?, b = 21.592 (6) A?, c = 15.199 (3) A?, V = 6634 (2) A?3, Z = 8, R(F) = 7.92%, Rw(F) = 8.92% for 2879 reflections with Fo ≥ 4σFo. The triangular metal core of 7c is symmetrically capped by a μ3-iodide ligand. Each Ru atom has two terminal CO's, and CO ligands bridge each of the Ru-Ru bonds. Cluster 7c can be reversibly protonated to form the known species HRu3(μ3-I)(CO)9. Cluster 7c also rapidly forms upon reaction of 3c with H2O, a reaction that also produces CO2 and H2, and 3c is a catalyst for the water gas shift reaction. When the reaction of Ru3(CO)12 with iodide was conducted under an H2/CO atmosphere, disproportionation occurred to form [HRu3(CO)11]- and [RuI3(CO)3]-. A similar reaction occurred when cluster 7c was placed under H2. Cluster 7c has also been found to thermally decompose to form [Ru6(CO)18]2- when heated to 100°C. However, at 140°C, 7c forms the carbide cluster [Ru6C(CO)16]2-. The reaction of Fe3(CO)12 with iodide has been reinvestigated and found to produce [Fe(CO)4I]- along with small amounts of [HFe3(CO)11]- that form from traces of water.