74552-70-8Relevant academic research and scientific papers
Facile preparation of Ru(CO)3(R-DAB) and its relation to the reversible C-C bond formation and fission between two R-DAB Ligands on a diruthenium fragment
Mul, Wilhelmus P.,Elsevier, Cornelis J.,Frühauf, Hans-Werner,Vrieze, Kees,Pein, Ingrid,Zoutberg, Martin C.,Stam, Casper H.
, p. 2336 - 2345 (2008/10/08)
Ru(CO)5 reacts with 1,4-diaza-1,3-butadienes (R-DAB; R = i-Pr (a), c-Hex (b), t-Bu (c), p-Tol (d)) to yield Ru(CO)3(R-DAB) (6a-d) together with a small amount of Ru2(CO)6(R-DAB) (1a-c) and an unidentified, probably organic product. The known complexes Ru2(CO)5(R-ADA) (7a,b; R-ADA = 1,6-di-R-1,6-diazahexa-1,5-diene-3,4-di-R-aminato), containing two C-C-coupled R-DAB ligands, and Ru2(CO)4(p-Tol-DAB)2 (8d), containing two σ-N,σ-N′,η2-C=N′-coordinated R-DAB ligands, react with CO at elevated temperatures to yield Ru(CO)3(R-DAB) (6a,b,d) as pure compounds in solution. The extremely air-sensitive mononuclear products (6) have been characterized by IR, 1H NMR, 13C NMR, and FD mass spectroscopy. The reactions are reversible. Photochemical or thermal activation of 6a,b,d in solution results in the re-formation of 7a,b or 8d, respectively. Irradiating a solution of 6a at -70°C yields a dark purple compound (I), which, on the basis of its chemical reactivity, is proposed to be an intermediate in the reversible C-C coupling/fission processes between two R-DAB ligands (7a,b ? 6a,b). Irradiating a solution of 6d in the presence of free p-Tol-DAB gives rise to another reaction that involves the formation of Ru(p-Tol-DAB)2(CO)2 (10d) and Ru(p-Tol-DAB)3 (11d). The C-C-coupled compound Ru2(CO)5(i-Pr-ADA) (7a) has been characterized by an X-ray structure determination. Crystals of 7a, C21H32N4O5Ru2, are monoclinic, space group P21/a, with cell constants a = 20.735 (6) A?, b = 15.847 (4) A?, c = 8.034 (2) A?, β = 100.25 (3)°, and Z = 4. A total of 2117 absorption corrected reflections have been used in the refinement resulting in a final R value of 0.054. The molecule consists of two Ru(CO)2 units bridged by a CO ligand and a formally 10e-donating i-Pr-ADA ligand. The observed short internuclear distance of 2.873 (2) A? is assumed to be a result of the bridging ligands forcing the metal atoms into proximity, since, on the basis of CVMO theory, no metal-metal bond is expected to be present. Furthermore, detailed information about the interconversions between R-DAB and R-ADA complexes has been acquired. It has been found, for instance, that the isomerization of Ru2(CO)4(R-ADA) (9a,b) to Ru2-(CO)4(R-DAB)2 (8a,b) only proceeds in the presence of a catalytic amount of CO. The corresponding catalytic cycle is discussed.
Ruthenium carbonyl 1,4-diaza-1,3-butadiene (R-DAB) reaction sequence. Reversible CO addition to a trinuclear species without rupture of a metal-metal bond. Molecular structure of [1,4-dicyclohexyl-1,4-diaza-1,3-butadiene]nonacarbonyltriruthenium, Ru3(CO)9(c-Hx-DAB): A unique 50e trinuclear compound with two elongated Ru-Ru bonds
Keijsper, Jan,Polm, Louis H.,Van Koten, Gerard,Vrieze, Kees,Seignette, Paul F. A. B.,Stam, Casper H.
, p. 518 - 525 (2008/10/08)
Ru3(CO)12 reacts with 1,4-disubstituted 1,4-diaza-1,3-butadienes, R-DAB = R-N=C(H)-C(H)=N-R (R = i-Pr, c-Hx, neo-Pent, i-Bu, p-Tol), to yield mononuclear Ru(CO)3(R-DAB) as a (c-Hx-DAB)) observable intermediate. This monomer reacts further with Ru3(CO)12 to give known dimeric Ru2(CO)n(R-DAB) (n = 5, 6) compounds. Dimeric Ru2(CO)6(c-Hx-DAB) reacts with Ru3(CO)12 to yield novel trinuclear Ru3(CO)9(c-Hx-DAB), which was characterized by an X-ray crystal structure determination. Crystals of Ru3(CO)9(c-Hx-DAB) are monoclinic, space group P21/n and cell constants a = 11.695 (2) ?, b = 10.306 (2) ?, c = 23.193 (3) ?, β = 102.73 (1)°, and Z = 4. A total of 2968 reflections have been used in the refinement, which results in a final R value of 0.034. In the triangular array of Ru atoms, there are two elongated Ru-Ru distances (Ru(1)-Ru(2) = 3.026 (1) ?, Ru(2)-Ru(3) = 2.956 (1) ?) while the third is normal (Ru(1)-Ru(3) = 2.793 (1) ?). All nine carbonyls are terminally bonded: four to Ru(3), three to Ru(2), and two to Ru(1). The c-Hx-DAB ligand is σ-N,σ-N′ coordinated to Ru(2) with equal, normal Ru-N distances of 2.13 (1) ? (mean). The four atoms of the N(1)=C(1)-C(2)=N(2) skeleton are located equal distances (2.22 (1) ?) (mean) from Ru(1), consistent with η2 coordination of both double bonds to Ru(1). Also, the bond lengths within this N(1)=C(1)-C(2)=N(2) part are equal (1.39 (1) ?) (mean), indicating that the diimine ligand is in a symmetrical 8e, σ-N,σ-N′,η2-C=N,η 2-C′=N′ coordination mode. As a consequence, Ru3(CO)9(c-Hx-DAB) is considered as a 50e - (3 × 8e (Ru) + 9 × 2e (CO) + 8e (c-Hx-DAB)) trinuclear species. Assuming 2e-2c Ru-Ru bonds, the structure does not obey the 18e rule, but it is shown that it can be interpreted on the basis of the polyhedral skeletal electron pair theory (PSEPT). Ru3-(CO)9(R-DAB) (R = neo-Pent, i-Bu), which have according to spectral data the same geometry as Ru3(CO)9(c-Hx-DAB), are instaneously formed in the reaction of Ru3(CO)8(R-DAB) with CO gas in toluene. This reaction can easily be reversed by heating Ru3(CO)9(R-DAB) in toluene or by treating it with Me3NO. The traffic light like color change during this reaction, which is reversible, is very remarkable: Ru3(CO)8(R-DAB) (bright green) + CO ? Ru3(CO)9(R-DAB) (bright red). Based on a structural comparison between Ru3(CO)8(R-DAB) and Ru3(CO)9(R-DAB), a rationale is given for the ease of CO addition, which does not lead to the complete rupture of bonds. Furthermore, the analogy between the reactions of Fe2(CO)9 and of Ru3(CO)12 with R-DAB is discussed. On the basis of PSEPT, the analogy between the reactions of Ru2(CO)5(R-DAB) and of isolobal Ru3-(CO)8(R-DAB) with CO is discussed.
Ruthenium carbonyl 1,4-diaza-1,3-butadiene (R-DAB) complexes. 5. Syntheses, spectroscopic properties, and reactivity of Ru2(CO)5(alkyl-DAB), a key intermediate in the Ru3(CO)12-alkyl-DAB reaction. Crystal and molecular structure of (1,4-diisopropyl-1,4-diaza-1,3-butadiene)pentacarbonyldiruthenium, Ru2(CO)5(i-Pr-DAB)
Keijsper, Jan,Polm, Louis,Van Koten, Gerard,Vrieze, Kees,Abbel, Gert,Stam, Casper H.
, p. 2142 - 2148 (2008/10/08)
Removal of a CO group from Ru2(CO)6(R-DAB) (1) (R-DAB = 1,4-disubstituted 1,4-diaza-1,3-butadiene, RN=C-(H)C(H)=NR), by heating or by treatment with Me3NO, results in the formation of a very reactive species Ru2(CO)5(R-DAB) (2) (R = i-Pr, c-Hx, t-Bu). During this reaction the coordination of the R-DAB ligand changes from the 6e (σ-N, μ2-N′, η2-C=N′) to the 8e (σ-N, σ-N′, η2-C=N, η2-C′=N′) mode, which was demonstrated by an X-ray structure determination of Ru2(CO)5(i-Pr-DAB). Crystals of Ru2(CO)5(i-Pr-DAB) are orthorhombic with space group P212121, cell constants a = 12.775 (2) A?, b = 13.518 (3) A?, and c = 9.636 (10) A?, and Z = 4. In the refinement, 1480 reflections were used, which results in a final R value of 0.045. The single Ru(1)-Ru(2) bond (2.741 (1) A?) is spanned by an asymmetric bridging carbonyl group with Ru(1)-C(3) (2.15 (1) A?) significantly longer than Ru(2)-C(3) (2.03 (1) A?), while the C(3)-O(3) vector is almost perpendicular (87°) to the Ru(1)-Ru(2) vector. The Ru-CO(terminal) bond lengths are equal, i.e. 1.86 (1) A? (mean). The i-Pr-DAB ligand has a flat N=CC=N skeleton and is chelate bonded to Ru(2) with two equal bond lengths (2.14 (1) A?) and η2-C=N,η2-C′=N′ bonded to Ru(1) with four equal bond lengths (2.27 (1) A?). The complexes have been further characterized by 1H NMR, IR, and FD mass spectroscopy. These techniques indicated similar geometries in solution and in the solid state. Ru2(CO)5(R-DAB) (2) reacts easily with CO, yielding Ru2(CO)6(R-DAB) (1) (R = i-Pr, c-Hx, t-Bu), and with R-DAB, yielding Ru2(CO)5(R-IAE) (3) (R = i-Pr, c-Hx, t-Bu; R-IAE = bis[(R-imino)(R-amino)ethane]) and Ru2(CO)4(neo-Pe-DAB)2 (3′). Thermal decomposition of Ru2(CO)5(R-DAB) yielded the known compound Ru4(CO)8(R-DAB)2 (4) (R = i-Pr, c-Hx, neo-Pe). Reaction with Fe2(CO)9 and Ru3(CO)12 yielded the novel complexes FeRu(CO)6(R-DAB) (5) (R = i-Pr, c-Hx, t-Bu) and Ru3(CO)8(R-DAB) (6) (R = neo-Pe, i-Bu), which were characterized by FD mass, IR, and NMR spectroscopy. These reactions prove that Ru2(CO)5(R-DAB) is a key intermediate in the Ru3(CO)12-R-DAB reaction sequence as well as in the earlier developed reactions of Ru2(CO)6(R-DAB) with unsaturated molecules.
