Kinetic studies in various media on some hydrogenation reactions catalyzed by polymer-anchored RhCl(PPh3)3

A study has been made of the hydrogenation of cyclohexene, 1-hexene and styrene at atmospheric pressure catalysed by RhCl (PPh₃)₃ supported on styrene-divinylbenzene copolymers with 1%, 2% and 4% cross linking. The dependence of the hydrogenation rate on the concentration of the olefin, the amount of catalyst, and the nature of the solvent was investigated. The hydrogenation rate is lower than for homogeneous catalysis but the dependence of the rate on the examined parameters is similar. The ratio between the rates for 1-hexene and cyclohexene is higher than that in the homogeneous phase. This increase in selectivity may due to steric hindrance around the active sites of the resin. The solvent effects revealed that the hydrogenation rate also depends on the degree of swelling of the resin.     

Selektive hydrierung von mesityloxid zu methylisobutylketon mit dem katalysator RhCl(PPh3)3

Mesityl oxide, dissolved in toluene is selectively hydrogenated to methylisobutylketone in the presence of the catalyst RhCl(PPh₃)₃. After 70% conversion the catalyst is deactivated. Without solvent, distilled but not degassed mesityl oxide is completely and selectively hydrogenated to methylisobutylketone. Turnover numbers are 4400. Under these hydrogenation conditions the catalyst is active for more than 100 hours.     

Katalysatoraktivität und umsatzzahlen bei der homogenen hydrierung mit RhCl(PPh3)3 und IrCl(CO)(PPh3)2 bei anaeroben und aeroben arbeiten

With toluene as solvent the type of time-turnover-curves obtained with homogeneous hydrogenation depends on the catalyst used as well as on the substrate. This holds for both anaerobic and aerobic hydrogenation conditions. Turnover numbers UZ from 0 to>6000 were observed. Under aerobic conditions, one gets higher turnover numbers with IrClCO(PPh₃)₂ and lower ones with RhCl(PPh₃)₃.     

On the catalytic duo PdCl2(PPh3)2/AuCl(PPh3) that cannot effect a Sonogashira-type reaction: a correction

In contrast to the observation made by the Laguna group, we report that the combination of PdCl₂(PPh₃)₂ and AuCl(PPh₃) makes a unique catalytic system that allows Sonogashira-type cross-coupling of both aryl and alkyl alkynes with aryl halides in excellent yields.     

Propionyl complexes of ruthenium derived from the reaction of ethylene with RuHCl(CO)2(PPh3)2

RuHCl(CO)₂(PPh₃)₂ reacts with ethylene under mild conditions (25 psi, 80°C) to yield a propionyl derivative RuCl(C[O]C₂H₅)(CO)(PPh₃)₂ which is believed to be coordinatively unsaturated. Unlike the acetyl analogue, RuCl[C[O]C₂H₅(CO)-(PPh₃)₂ does not isomerize to RuCl(C₂H₅)(CO)₂(PPh₃)₂ in solution. Under one atmosphere of carbon monoxide, RuCl(C[O]C₂H₅(CO)(PPh₃)₂ exists in equilibrium with two species believed to be RuCl(C[O]C₂H₅)(CO)₂(PPh₃)₂ and [Ru(C[O]C₂H₅)(CO)₃(PPh₃)₂]Cl. RuCl(C[O]C₂H₅)(CO)(PPh₃)₂ reacts with CO/ AgClO₄ to give mer-[Ru(C[O]C₂H₅)(CO)₃(PPh₃)₂]ClO₄, p-tolylisocyanide (RNC) and NaClO₄ to give cis-[Ru(C[O]C₂H₅)(CO)(CNR)₂(PPh₃)₂ClO₄, and hydrochloric acid to yield the hydroxycarbene complex, RuCl₂(CO)(C[OH]C₂H₅)(PPh₃)₂.     

Application of a stereospecific RhCl(PPh3)3 decarbonylation reaction for the total synthesis of 7-(±)-deoxypancratistatin

A highly efficient total synthesis of 7-deoxypancratistatin is described. The synthesis features the ready preparation of the phenanthridone skeleton by a Stille-IMDAF cycloaddition cascade. The resulting cycloadduct is converted into a key aldehydic intermediate, which is then induced to undergo a stereospecific decarbonylation reaction using Wilkinson’s catalyst to set the trans B-C ring junction of the target molecule.     

Synthesis and characterisation of HRuRh3(CO)12. Crystal structures of HRuRh3(CO)12, HRuRh3(CO)10(PPh3)2 and HRuCo3(CO)10(PPh3)2

A new ruthenium-rhodium mixed-metal cluster HRuRh₃(CO)₁₂ and its derivatives HRuRh₃(CO)₁₀(PPh₃)₂ and HRuCo₃(CO)₁₀(PPh₃)₂ have been synthesized and characterized. The following crystal and molecular structures are reported: HRuRh₃(CO)₁₂: monoclinic, space group P2₁/c, a 9.230(4), b 11.790(5), c 17.124(9) Å, β 91.29(4)°, Z = 4; HRuRh₃(CO)₁₀(PPh₃)₂·C₆H₁₄: triclinic, space group P$\text{1}$, a 11.777(2), b 14.079(2), c 17.010(2) Å, α 86.99(1), β 76.91(1), γ 72.49(1)°, Z = 2; HRuCo₃(CO)₁₀(PPh₃)₂·CH₂Cl₂: triclinic, space group P$\text{1}$, a 11.577(7), b 13.729(7), c 16.777(10) Å, α 81.39(4), β 77.84(5), γ 65.56°, Z = 2. The reaction between Rh(CO)₄^? and (Ru(CO)₃Cl₂)₂ tetrahydrofuran followed by acid treatment yields HRuRh₃(CO)₁₂ in high yield. Its structural analysis was complicated by a 80–20% packing disorder. More detailed structural data were obtained from the fully ordered structure of HRuRh₃(CO)₁₀(PPh₃)₂, which is closely related to HRuCo₃(CO)₁₀(PPh₃)₂ and HFeCo₃(CO)₁₀(PPh₃)₂. The phosphines are axially coordinated.     

The tris(triphenylphosphine)osmium zerovalent complexes Os(CO)2(PPh3)3, .Os(CO)(CNR)(PPh3)3, Os(CO)(CS)(PPh3)3, Os(CS)(cNR)(PPh3)3 and derived compounds

Detailed procedures for the syntheses of Os(CO)₂(PPh₃)₃, Os(CO)(CNR)-(PPh₃)₃ (R = p-tolyl), Os(CO)(CS)(PPh₃)₃ and Os(CS)(CNR)(PPh₃)₃, together with the derived complexes Os(CO)₂(CS)(PPh₃)₂, Os(CO)(CS)(CNR)(PPh₃)₂, Os(η²-C₂H₄)(CO)(CNR)(PPh₃)₂, Os(η²-C₂H₄)(CO)(CS)(PPh₃)₂, Os(η²CS₂)(CO)₂-(PPh₃)₂, Os(η²CS₂)(CO)(CS)(PPh₃)₂, Os(η²-CS₂)(CO)(CNR)(PPh₃)₂, Os(η²PhC₂Ph)(CO)₂(PPh₃)₂ and OsH(C2Ph)(CO)₂(PPh₃)₂ are described.     

Stereochemical nonrigidity of the square complex (PPh3)2Pt(HgGePh3)(GePh3)

³¹P, ¹⁹⁵Pt and ¹⁹⁹Hg NMR spectra of complex (PPh₃)₂Pt(HgGePh₃)(GePh₃) (I) have been studied. The spectra at temperatures below ?40°C prove that (I) is a cis-isomer with the square-planar coordination of the Pt atom. The reversibility of temperature dependences of spectra, insensitivity of line shape to the solvent, concentration and presence of free phosphine establish the fluxional behaviour of (I). The activation parameters of the intramolecular rearrangement which is realized, most probably, through a digonal twist, are: Δ^≠₂₉₈ = 51.5 ± 2.9 kJ/mol, ΔH^≠ = 59.3 ± 2.9 kJ/mol, ΔS^≠ = 26.2 ± 9.7 J/mol. K.     

Formation and structural characterization of novel polynuclear palladium selenolato complexes [Pd3Se(SePh)3(PPh3)3]Cl and [Pd6Cl2Se4(SePh)2(PPh3)6]

In addition to well-known dinuclear phenylselenolato palladium complexes, the reaction of [PdCl₂(PPh₃)₂] and NaSePh affords small amounts of novel trinuclear and hexanuclear complexes [Pd₃Se(SePh)₃(PPh₃)₃]Cl (1) and [Pd₆Cl₂Se₄(SePh)₂(PPh₃)₆] (2). Complex 1 is triclinic, P1?, a=13.6310(2), b=16.2596(2), c=16.9899(3) Å, α=83.1738(5), β=78.9882(5), γ=78.7635(5)°. Complex 2 is monoclinic, C2/c, a=25.7165(9), b=17.6426(8), c=27.9151(14) Å, β=110.513(2)°. There are no structural forerunners for 1, but the hexanuclear complex 2 is isostructural with [Pd₆Cl₂Te₄(TeR)₂(PPh₃)₆] (R=Ph, C₄H₃S) that have been observed as one of the products in the oxidative addition of R₂Te₂ to [Pd(PPh₃)₄]. Mononuclear palladium complexes may play a significant role as building blocks in the formation of the polynuclear complexes.     

Photoinduced formation of phosphido-bridged clusters derived from Ru3(CO)9(PPh2H)3. Crystal and molecular structure of Ru3(μ-H)(μ-PPh2)3(CO)7

The new complex Ru₃(CO)₉(PPh₂H)₃ (I) was prepared by the direct thermal reaction of Ru₃(CO)₁₂ with PPh₂ H and was spectroscopically characterized. Irradiation of I with λ ≥ 300 nm leads to the formation of Ru₂(μ-PPh₂)₂(CO)₆ (II) and three new phosphido-bridged complexes, Ru₃(μ-H)₂(μ-PPh₂)₂(CO)₈ (III), Ru₃(μ-H)₂(μ-PPh₂)₂(CO)₇(PPh₂H) (IV) and Ru₃(μ-H)(μ-PPh₂)₃(CO)₇ (V). These complexes have been characterized spectroscopically and Ru₃ (μ-H)(μ-PPh₂)₃(CO)₇ by a complete single crystal X-ray structure determination. It crystallizes in the space group P2₁/n with a 20.256(3), b 22.418(6), c 20.433(5) Å, β 112.64(2)°, V 8564(4) ų, and Z = 8. Diffraction data were collected on a Syntex P2₁ automated diffractometer using graphite-monochromatized Mo-K_α radiation, and the structure was refined to R_F 4.76% and R_wF 5.25% for the 8,847 independent reflections with F₀ > 6σ(F₀). The structure consists of a triangular array of Ru atoms with seven terminal carbonyl ligands, three bridging diphenylphosphido ligands which bridge each of the RuRu bonds, and the hydride ligand which bridges one RuRu bond. Complex IV was also shown to give V upon photolysis and is thus an intermediate in the photoinduced formation of V from I.     

The reaction of (μ-H)2Os3(CO)9(PPh3) with ethylene affords the ethylidene complex (μ-H)2Os3(CO)9(PPh3)(μ-CHCH3)

The product isolated from the reaction of (μ-H)₂Os₃(CO)₉(PPh₃) with ethylene is shown to be the ethylidene complex (μ-H)₂Os₃(CO)₉(PPh₃)(μ-CHCH₃) (1) rather than the ethylene complex (μ-H)(H)Os₃(CO)₉(PPh₃)(C₂H₄), as previously claimed. The characterization of 1 is based on a combination of ¹H and ¹³C NMR results. The ¹H NMR data (δ 6.84 (1 H_D), 2.53 (3 H_C), J(CD) = 7.4 Hz) establish the presence of the ethylidene moiety, whereas detailed analysis of the 1-D and 2-D ¹³C NMR spectra of ¹³CO-enriched 1 indicates the relative positions of the ethylidene, hydride, and phosphine ligands on the triosmium framework.     

Four isomers from the oxidative addition of Me3SnH to Os(CO)2(PPh3)3 and the crystal structure of Os(SnMeI2)I(CO)2(PPh3)2, in which the pairs of CO and PPh3 ligands are mutually trans

Reaction between Os(CO)₂(PPh₃)₃ and Me₃SnH produces Os(SnMe₃)H(CO)₂(PPh₃)₂ (1). Multinuclear NMR studies of solutions of 1 reveal the presence of four geometrical isomers, the major one being that with mutually cis triphenylphosphine ligands and mutually trans CO ligands. Os(SnMe₃)H(CO)₂(PPh₃)₂ undergoes a redistribution reaction, at the trimethylstannyl ligand, when treated with Me₂SnCl₂ giving Os(SnMe₂Cl)H(CO)₂(PPh₃)₂ (2). Solutions of 2 again show the presence of four isomers but now the major isomer is that with mutually trans triphenylphosphine ligands and mutually cis CO ligands. The redistribution reaction of 1 with SnI₄ produces Os(SnMeI₂)H(CO)₂(PPh₃)₂ (3) which exists in solution as only one isomer, that with mutually trans triphenylphosphine ligands and mutually trans CO ligands. Treatment of 3 with I₂ cleaves the Os-H bond with retention of geometry giving Os(SnMeI₂)I(CO)₂(PPh₃)₂ (4). The crystal structure of 4 has been determined. No isomerization of the trans dicarbonyl complex 4 occurs when 4 is heated, instead there is a formal loss of “MeSnI” and formation of OsI₂(CO)₂(PPh₃)₂ (5).     

Thiocarbonyl complexes of ruthenium(II). Synthesis of RuCl2(CS)(H2O)(PPh3)2 and RuHCl(CS)(PPh3)3

A high-yield synthesis of trans-RuCl₂(CS)(H₂O)(PPh₃)₂ from RuCl₂(PPh₃)₃ and CS₂ is described. The coordinated water molecule is labile, and introduction of CNR (R  p-toyl or p-chlorophenyl) leads to yellow trans-RuCl₂(CS)(CNR)(PPh₃)₂, which isomerises thermally to colourless cis-RuCl₂(CS)(CNR)(PPh₃)₂. Reaction of AgClO₄ with cis-RuCl₂(CS)(CNR)(PPh₃)₂ gives [RuCl(CS)(CNR)(H₂O)(PPh₃)₂]⁺, from which [RuCl(CS)(CO)(CNR)(PPh₃)₂]⁺ and [RuCl(CS)(CNR)₂(PPh₃)₂]⁺ are derived. Reaction of trans-RuCl₂(CS)(H₂O)(PPh₃)₂ with sodium formate gives Ru(η²-O₂CH)Cl(CS)(PPh₃)₂, which undergoes decarboxylation in the presence of (PPh₃) to give RuHCl(CS)(PPh₃)₃. Ru(η²-O₂CH)H(CS)(PPh₃)₂ and Ru(η²-O₂CMe)-H(CS)(PPh₃)₂ are also described.     

Some spectroscopic and freezing point depression measurements on the homogeneous hydrogenation catalyst CoH3(PPh3)3

NMR, EPR and freezing point depression (FPD) experiments were performed on solutions of the homogeneous hydrogenation catalyst CoH₃(PPh₃)₃. The results of these measurements show that the compound has a dynamic structure on the NMR time scale at room temperature and that it is slightly dissociated into bisphosphine species and free phosphine. FPD and¹H-NMR measurements indicate that one Et₂O molecule is present per catalyst molecule.

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, () CoH₃(PPh₃)₃. , , . H¹- , Et₂O.

     

Mo(CO)3(NCMe)(PPh3)2: Synthesis, X-ray structure and evaluation of its catalytic activity for the homogeneous hydrogenation of olefins and their mixtures

The complex Mo(CO)₃(NCMe)(PPh₃)₂, was synthesized by the reaction of Mo(NCMe)₃(CO)₃ with two equivalents of PPh₃ and characterized by UV–Vis, IR, NMR and X-ray diffraction. This complex was used as a catalyst precursor for the hydrogenation of 1-hexene, styrene, cyclohexene and 2,3-dimethyl-1-butene and their mixtures under moderate conditions in homogeneous media. Under mild reaction conditions (T = 373 K, P = 60 atm), the substrates showed the following reactivity order: styrene > 1-hexene > cyclohexene > 2,3-dimethyl-1-butene. A quaternary equimolar mixture showed a different hydrogenation order: 1-hexene > cyclohexene > styrene > 2,3-dimethyl-1-butene; the presence of dibenzothiophene or mercury does not interfere with the activity of the catalyst.     

Structure and bonding in a series of cyano complexes: RuCp(PPh3) 2CN, [RuCp(PPh3) 2(CNH)]CF3SO3, and H-bridged [Ru2(Cp) 2(PPh3) 4CNHNC]CF3SO3

The three title cyanoruthenium complexes have been characterized by means of X-ray diffraction analysis, IR and NMR solution spectroscopies, as well as extended Hückel molecular orbital calculations examining the properties of the cyanide fragment changing with complexation and with the co-ligands Cp and PPh₃. Explanations are given for crystallographic results of the C-N bond shortening upon complexation, the supershort (2.573 Å) bond length of N(H) N in the bridged complex, as well as the Ru-C-N and C-N-H-N-C bendings. Although the crystallographically found asymmetry of coordinated Cp is not significant, the MO calculations suggest a distorted endocyclic bond-length pattern indicative of the relative importance of σ and π bonding in the metalcyclopentadienyl interactions.