Wolfram Stüer

Ruthenium Trichloride, Tricyclohexyl‐ phosphane, 1‐Alkynes, Magnesium, Hydrogen, and Water—Ingredients of an Efficient One‐Pot Synthesis of Ruthenium Catalysts for Olefin Metathesis

An active role is played by MgCl2 during the conversion of the vinylidene precursor 2 into carbenes 3 (R=H, Ph; L=P(C6 H11 )3 ). These complexes can be prepared in a convenient and very efficient one-pot synthesis and have a catalytic activity in metathesis comparable to that of Grubbs compound (Ph instead of CH2 R).

Carbynehydridoruthenium Complexes as Catalysts for the Selective, Ring-Opening Metathesis of Cyclopentene with Methyl Acrylate

The first members of a homologous series of long-chain, multiply unsaturated esters were obtained upon selective ring-opening metathesis of cyclopentene with methyl acrylate [Eq. (a)]. The catalysts are cationic carbynehydridoruthenium complexes (e.g. L=OEt2 ), which were prepared for the first time by protonation of hydridovinylideneruthenium compounds in the presence of L.

Synthesis, crystal structure and electrochemistry of bis(N,N-dimethylammonium) tris(1,2-benzenedithiolato)titanate(IV)

Abstract Synthesis, electrochemical and structural data for [NH2(CH3)2]2[Ti(S2C6H4)3] (1 are described. Treating Ti{N(CH3)2}4 with 1,2-(HS)2C6H4 in a 1 : 3 ratio affords 1 in 94% isolated yield. Dark red single crystals of 1, suitable for X-ray crystallography, were obtained from CH3CNEt2O mixtures. The molecular structure of the anion of 1, [Ti(S2C6H4)3]2−, provides a rare example of a homoleptic thiolate complex of titanium, but more importantly, the titanium centre contains the unusual TiS6 coordination of a skew-trapezoidal bipyramid (S-TzBP) with angular coordinates φA = 60°, φB = 140E = 75°. The S6 polyhedron in 1 can be alternatively described as a pentagonal bipyramid with an equatorial vertex missing. A spectropotentiostatic experiment for 1 verified that a reversible one-electron reduction occurs at −1.51 V (vs Ag/AgCl, DMF). The electrochemical product was characterized by UV-vis (347, 414 and 434 nm) and ESR (77 K, rhombic: g1 = 2.18 g2 = 2.04 and g3 = 2.00) spectroscopies.

Synthesis and Molecular Structure of Six‐Coordinate Dichlorodihydridoruthenium(IV) and Five‐Coordinate Vinylideneruthenium(II) Complexes

The dichlorodihydridoruthenium(IV) compound [RuH2Cl2(PiPr3)2] (4) was prepared from [RuCl2(C8H12)]n (3), PiPr3, and H2 in 2-butanol via the chlorohydridoruthenium(II) derivative [RuHCl(H2)(PiPr3)2] (5) as an intermediate. The synthesis of 5 was achieved under similar conditions from 3, PiPr3, H2, and 2-butanol in the presence of NEt3. Compound 4, which was characterized by X-ray crystal structure analysis, reacts with excess phenylacetylene to give the phenylvinylidene complex [RuCl2(=C=CHPh)(PiPr3)2] (7) and with propargylic alcohols or derivatives thereof to afford the vinylcarbene complexes [RuCl2(=CHCH=CR2)(PiPr3)2] (9, 10), respectively. From 5 and terminal alkynes RC≡CH the chlorohydridovinylidene compounds [RuHCl(=C=CHR)(PiPr3)2] (11, 12) were obtained. The phenylvinylidene complex [RuCl2(=C=CHPh)(PCy3)2] (15) was prepared from phenylacetylene and either [RuH2Cl2(PCy3)2] (14) or one of the carbene deriva-tives [RuCl2(=CHR)(PCy3)2] (16, 17) as starting materials. The X-ray crystal structure analysis of 15 confirms a distorted square-pyramidal geometry with the vinylidene ligand in the apical position. The interconversion of 4 to 5 and of the tricyclohexylphosphane counterparts 14 to 13 was achieved by hydrogen transfer from 2-propanol in the presence of PR3. The reverse reaction occurs upon treatment of 5 or 13 with the corresponding phosphonium salt [HPR3]Cl or HCl, respectively.

RuCl3, P(C6H11)3, 1-Alkine, Mg, H2 und H2O: Komponenten einer effizienten Eintopfsynthese von Ru-Olefinmetathese- Katalysatoren

Eine aktive Rolle spielt MgCl2 bei der Umwandlung der Vinylidenvorstufe 2 in die Carbenkomplexe 3 (R = H, Ph; L = P(C6H11)3). Diese lassen sich durch die Reaktion von 1 mit 1-Alkinen in einer einfachen und sehr effizienten Eintopfsynthese herstellen und weisen bei der Olefinmetathese eine ahnliche Katalyseaktivitat auf wie die von Grubbs entwickelte Verbindung (mit Ph statt CH2R).

Preparation of Trifluorophosphaneruthenium(II) Complexes from η3:η3-Cyclooctadienediylruthenium(IV) Compounds as Precursors

The dinuclear cyclooctadienediylruthenium(IV) compound [{RuCl2(η3:η3-C10H16)}2] (1) reacts with PCy3 in 2-propanol under an H2 atmosphere to give the hydrido(dihydrogen) complex [RuHCl(H2)(PCy3)2] (2) in nearly quantitative yield. Treatment of 1 with PCy3, PiPr3 or PiPr2Ph under argon affords the mononuclear products [RuCl2(η3:η3-C10H16)(PR3)] (3−5) by chloride-bridge cleavage. The corresponding compound 6 with PF3 as phosphane ligand reacts with PCy3 by nucleophilic attack of PCy3 at the carbon atom C3 of the dienediyl chain to give the zwitterionic η2:η3-alkene(allyl)ruthenium(II) complex [RuCl2{η2:η3-CH2=C(Me)−CH(PCy3)(CH2)2CHC(Me)CH2}(PF3)] (7) the crystal and molecular structures of which have been determined. The reaction of 7 with excess PCy3 in the presence of H2 affords the five-coordinate hydrido compound [RuHCl(PF3)(PCy3)2] (8), which upon treatment with acetylene gives the vinyl derivative [RuCl(CH=CH2)(PF3)(PCy3)2] (9). The related cationic carbene complex [RuCl(=CHCH3)(PF3)(PCy3)2]BF4 (10) is obtained by protonation of 9 with HBF4 in ether. (© Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002)

A tertiary phosphine that is too bulky: preparation of catalytically less active carbene and vinylidene ruthenium(II) complexes

Tricyclooctylphosphine PCoc3 (1), which has been prepared from PCl3 and cyclooctyl Grignard reagent, reacts under an atmosphere of H2 with the dimer [RuCl2(η3:η3-C10H16)]2 (2) to give the hydrido(dihydrogen) complex [RuHCl(H2)(PCoc3)2] (4); in contrast, treatment of 2 with PPh3 under the same conditions affords [RuHCl(PPh3)3] (3). The reaction of 4 with acetylene in the presence of MgCl2 and water leads to the formation of the ruthenium carbene [RuCl2(CHCH3)(PCoc3)2] (5) in 70% isolated yield. In the absence of MgCl2 and water, 4 reacts with acetylene at low temperature to give the hydrido(vinylidene) complex [RuHCl(CCH2)(PCoc3)2] (6) almost quantitatively. Compounds 5, 6 and [RuH(κ2-O2CCF3)(CCH2)(PCoc3)2] (7), the latter being obtained from 6 and CF3CO2K by ligand exchange, are poor catalysts for ROMP and cross olefin metathesis.

HYDRIDO(CARBENE), HYDRIDO(DIAZOALKANE), AQUA-(CARBENE), AND VINYL(CARBENE)COMPLEXES OF OSMIUM(II)

The five-coordinate compound [OsHCl(CO)(PiPr3)2] (1) reacts with CH2N2 and other diazoalkanes RCHN2 (R = Ph, CO2Et, SiMe3) in ether or toluene at 25 °C to give instead of the expected insertion products [Os(CH2R)Cl(CO)(PiPr3)2] the isomeric hydrido(carbene)osmium(II) complexes [OsHCl(=CHR)(CO)(PiPr3)2] (2–5) in excellent yields. With Me3SiCHN2 as the substrate, the 1:1 adduct [OsHCl(N2CHSiMe3)(CO)(PiPr3)2] (6) was detected at low temperature as an intermediate. The reactions of 1 with Ph2CN2 and Cl4C5N2 afford the hydrido(diazoalkane)compounds [OsHCl(N2CR2)(CO)(PiPr3)2] (7, 8), which are quite stable and do not eliminate N2 to give the corresponding hydrido(carbene)metal derivatives. Treatment of 3 (R = Ph) with either HCl or HBF4/H2O leads to the cleavage of the Os-H bond and results in the formation of [OsCl2(=CHPh)(CO)(PiPr3)2] (10) and [OsCl(=CHPh)(OH2)(CO)(PiPr3)2]BF4 (11), respectively. The vinyl compound [OsCl(CH=CHPh)(CO)(PiPr3)2] (12) behaves similarly to 1 and affords the carbene complex [OsCl(CH=CHPh)(=CHPh)(CO)(PiPr3)2] (13) upon treatment with PhCHN2. Compound 13 rearranges in solution at room temperature to give the π-allyl complex [Os(η3-PhCHCHCHPh)Cl(CO)(PiPr3)2] (14) as the dominating species. The crystal and molecular structures of 4, 5, 10, and 11 have been determined by X-ray crystallography.

Hydrido(carbonyl) and Hydrido(carbene) Complexes of Ruthenium

The five-coordinate compound [RuHCl(CO)(PiPr2Ph)2] (1), which was prepared from RuCl3· 3 H2O and PiPr2Ph in methanol in the presence of NEt3, reacts with CO and with diazoalkanes RCHN2 (R = Ph, H) to give the six-coordinate complexes [RuHCl(CO)2(PiPr2Ph)2] (4) and [RuHCl(CO)(=CHR)(PiPr2Ph)2] (5, 6), respectively. If the reaction of 1 with CH2N2, which at –78 °C affords 6, is carried out at room temperature, the ionic compound [MePiPr2Ph][RuHCl2(CO)(PiPr2Ph)2] (7) is formed. The corresponding PPN salt was obtained from 1 and [PPN]Cl. The X-ray crystal structure analysis of 7 revealed, that the anionic species [RuHCl2(CO)(PiPr2Ph)2]− contains the chloro ligands in cis and the phosphanes in trans disposition. The Ru=CH2 bond of compound 6 is quite labile and, therefore, the CH2 unit is easily displaced by CO or pyridine. From 1 and pyridine, an isomeric mixture of [RuHCl(CO)(py)(PiPr2Ph)2] (9a, b) is formed. Treatment of 1 with HC≡CR (R = H, Ph) yields the five-coordinate vinylruthenium(II) complexes [Ru(CH=CHR)Cl(CO)(PiPr2Ph)2] (12, 13) by insertion of the alkyne into the Ru–H bond. The preparation of [RuHX(CO)-(PiPr2Ph)2] (X = CF3CO2, I) is also reported.

Preparation of hydrido(vinylidene)ruthenium(II) complexes and a one-pot synthesis of Grubbs-type ruthenium carbenes

Treatment of the hydrido(dihydrogen) compound [RuHCl(H2)(PCy3)2] 1 with alkynes RC[triple bond, length as m-dash]CH (R=H, Ph) afforded the hydrido(vinylidene) complexes [RuHCl(=C=CHR)(PCy3)2] 2, 3 which react with HCl or [HPCy3]Cl to give the corresponding Grubbs-type ruthenium carbenes [RuCl2(=CHCH2R)(PCy3)2] 4, 5. The reaction of 2 (R=H) with DCl, or D2O in the presence of chloride sources, led to the formation of [RuCl2(=CHCH2D)(PCy3)2] 4-d1. Based on these observations, a one-pot synthesis of compounds 4 and 5 was developed using RuCl3.3H2O as the starting material. The hydrido(vinylidene) derivative 2 reacted with CF3CO2H and HCN at low temperatures to yield the carbene complexes [RuCl(X)(=CHCH3)(PCy3)2] 6, 7, of which 7 (X=CN) was characterized crystallographically. Salt metathesis of 2 with CF3CO2K and KI led to the formation of [RuH(X)(=C=CH2)(PCy3)2] 8, 9. The bis(trifluoracetato) and the diiodo compounds [RuX2(=CHCH3)(PCy3)2] 10, 11 as well as the new phosphine P(thp)3 12 (thp=4-tetrahydropyranyl) and the corresponding complex [RuCl2(=CHCH3){P(thp)3}2] 14 were also prepared. The catalytic activity of the ruthenium carbenes 4-7, 10, 11 and 14 in the olefin cross-metathesis of cyclopentene and allyl alcohol was investigated.