Kinetics of hydroformylation of 1-decene using carbon-supported ossified HRh(CO)(TPPTS)3 catalyst

The kinetics of hydroformylation of 1-decene has been investigated using a carbon-supported ossified HRh(CO)(TPPTS)₃/Ba catalyst in a temperature range of 343–363 K. The effect of concentration of 1-decene, catalyst loading, partial pressure of H₂ and CO, and stirring speed on the reaction rate has been investigated. A first-order dependence was observed for catalyst concentration and hydrogen partial pressure. The rate showed a typical case of substrate inhibition for high 1-decene concentration. The rate varied with a linear dependence on P_CO up to a CO partial pressure of 5–6 MPa in contrast to the general trends; for most of the rhodium-phosphine catalyzed hydroformylation reactions, severe inhibition of rate is observed with an increase in CO pressure. A rate equation has been proposed, which was found to be in good agreement with the observed rate data within the limit of experimental errors. The kinetic parameters and activation energy values have been reported.     

Properties of triphenylphosphite-modified rhodium carbonyl catalysts for the hydroformylation of 2-butenes

The factor responsible for the deactivation of a carbonyl triphenylphosphite rhodium hydroformylation catalyst appears to be the formation of a chelate-structure complex with diphenylphosphite, which is the product of partial hydrolysis of the organophosphorus ligand. The deactivating effect of diphenylphosphite can be suppressed upon interaction of the H(O)P(OPh)₂ and P(OPh)₃-modified complex with 2-butenes under hydroformylation reaction conditions.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 12, pp. 2712–2716, December 1990.     

Rhodium/tris-binaphthyl chiral monophosphite complexes: Efficient catalysts for the hydroformylation of disubstituted aryl olefins

A family of threefold symmetry phosphite ligands, P(O–BIN–OR)₃ (BIN = 2,2′-binaphthyl; R = Me, Bn, CHPh₂, 1-adamantyl), derived from enantiomerically pure (R)-BINOL, was developed. Cone angles within the range 240–270° were calculated for the phosphite ligands, using the computational PM6 Hamiltonian. Their rhodium complexes formed in situ showed remarkable catalytic activity in the hydroformylation of hindered phenylpropenes, under relatively mild reaction conditions, with full chemoselectivity for aldehydes, high regioselectivity, however with low enantioselectivity. The ether substituents at the ligand affected considerably the catalytic activity on the hydroformylation of 1,1- and 1,2-disubstituted aryl olefins. The kinetics of the hydroformylation of trans-1-phenyl-1-propene, using tris[(R)-2′-benzyloxy-1,1′-binaphthyl-2-yl]phosphite as model ligand, was investigated. A first order dependence in the hydroformylation initial rate with respect to substrate and catalyst concentrations was found, as well as a positive order with respect to the partial pressure of H₂, and a slightly negative order with respect to phosphite concentration and CO partial pressure.     

Low pressure,highly active rhodium catalyst for the homogeneous hydroformylation of olefins

Hex-1-ene hydroformylation was examined at pressures of 1–11 atm and 40 °C, using Rh(acac)[P(OPh)₃]₂ + P(OPh)₃ as catalyst. The highest efficiency of aldehydes was achieved employing a small P(OPh₃)₃ excess-[P(OPh)₃]:[Rh] = 2:1. For reactions carried out at 1 atm, very high n/iso ratios i.e. 10–80 were obtained. Pressure increase caused a systematic drop of the n/iso ratio to ca. 5 at 11 atm. Simultaneously with hydroformylation, isomerisation of hex-1-ene to hex-2-ene occurs, but the contribution of the latter declines with increasing pressure. IR examination of the reaction mixture revealed that HRh(CO)[P(OPh)₃]₃ was the active form of the catalyst.The same catalytic system was applied in propylene hydroformylation at 5–10 atm pressure and 40 °C. In such conditions the yield of aldehydes was 10–70%, with a n/iso selectivity of 2–10.     

Synthesis and reactivity of rhodium(I) complexes of the type Rh(L-L)(CO)[P(OPh)3] and Rh(L-L)[P(OPh)3]2

Summary The carbonyl ligands in the Rh¹ complexes Rh(L-L)(CO)₂ [L-L=anthranilate (AA) orN-phenylanthranilate(FA) ions] are replaced by P(OPh)₃ to form the mono-or disubstituted products, Rh(L-L)(CO)[P(OPh)₃] and Rh(L-L)[P(OPh)₃]₂ respectively depending on the [P(OPh)₃]/[Rh] molar ratio, at room temperature and in air. Under argon at [P(OPh)₃]/[Rh]4 theortho-metallated Rh¹ complex Rh[P(OPh)₃]₃[P(OC₆H₄)-OPh)₂] is formed. The new route forortho-metallated Rh¹ complex synthesis is described.The Rh(AA)(CO)₂ complex was used as a catalyst precursor in hydroformylation of olefins.     

New trends in the kinetics of hydroformylation of vinyl acetate using Rh complex catalysts

The kinetics of hydroformylation of vinyl acetate using [Rh(CO)₂Cl]₂ complex catalyst has been investigated at 80 °C. The trends are quite different from those observed for the HRh(CO)(PPh₃)₃-catalyzed systems. The dependence of the rate on P(H₂) and P(CO) was found to be linear, whereas the dependence of rate on vinyl acetate concentration was found to be first order, followed by substrate-inhibited kinetics at higher olefin concentrations. The rate dependence on the catalyst concentration was found to be fractional order. A rate equation has been proposed and kinetic parameters evaluated.     

The synthesis,structure and reactivity of new tetra- and pentacoordinated rhodium(I) complexes

Summary Tetracoordinated complexes of the [Rh{P(OPh)₃}₃X] type (X=N₃, NO₂ or NCS) were obtained in the reaction of [Rh{P(OPh)₃}₃Cl] with NaX. Pentacoordinated [Rh{P(OPh)₃}₄X] complexes (X=HSO₄, H₂PO₄, MeCO₂, HCO₂ or ClO₄) were prepared by treating [Rh{P(OPh)₃}₃ {P(OC₆H₄)(OPh)₂}] or [Rh(acac) {P(OPh)₃}₂]+P(OPh)₃ (Hacac=acetylacetone) with acids HX.The groups of complex differ in reactivity towards CO and H₂; [Rh{P(OPh)₃}₃X] complexes do not react with dihydrogen and with CO they produce [Rh{P(OPh)₃}₂(CO)X]. The [Rh{P(OPh)₃}₄X] complexes take up H₂ reversibly, and with CO they give [Rh{P(OPh)₃}₃(CO)₂X] compounds.     

The reaction of mixtures of [Rh4(CO)12] and triphenylphosphite with carbon monoxide or syngas as studied by high-resolution, high-pressure NMR spectroscopy

The fragmentation and redistribution reactions of [Rh4(CO)12-x{P(OPh)3}x] (x = 1-4) with carbon monoxide have been studied using high-resolution, high-pressure NMR spectroscopy. Under the conditions of efficient gas mixing in a high-pressure NMR bubble column, [Rh4(CO)9{P(OPh)3}3] fragments to give mainly [Rh2(CO)6{P(OPh)3}2]; [Rh4(CO)11{P(OPh)3}] is also observed,implying redistribution of the phosphite ligand and/or recombination of the dimers to tetrameric clusters. Fragmentation of[Rh4(CO)10{P(OPh)3}2] is found to be pressure-dependent giving predominantly [Rh2(CO)6{P(OPh)3}2] at low CO pressure (1-40 bar), and increasing amounts of [Rh2(CO)7{P(OPh)3}] at higher (40-80 bar) pressure. Using Syngas (CO : H2 (1 : 1)) instead of CO in the above fragmentations, homolytic addition of H2 to the dimer [Rh2(CO)6{P(OPh)3}2] to give [RhH(CO)3{P(OPh3}] and [RhH(CO)2{P(OPh)3}2] is observed. The distribution of tetrameric species obtained is similar to that obtained under the same partial pressure of CO. On depressurisation/out-gassing of the sample, the original mixture of tetrameric clusters is obtained.     

Ferrofluid catalyzed water gas shift reaction to give carbon-dioxide and hydrogen

A ferrofluid consisting of colloidally dispersed magnetite particles in water was found to be an efficient selective catalyst for water gas shift reaction at 15–25 atmosphere of CO pressure in the temperature range of 423–553 K where the products obtained were only CO₂ and H₂. The reaction was studied as a function of variation of the concentration of catalyst, pressure of CO gas and temperature. Kinetic parameters suggested a mechanism involving first order dependence in CO and catalyst concentrations.     

Direct synthesis of acetals by rhodium catalysed hydroformylation of alkenes in the presence of orthoformate

The two catalyst precursors [Rh₂(μ-penicillamine)₂(CO)₄][OTf]₂ and [Rh₂(μ-cysteine)₂(CO)₄][OTf]₂ in the presence of 4 equivalents of P(OPh)₃ in triethyl orthoformate as solvent and reactant, permit the low pressure hydroformylation of various alkenes into the corresponding acetals. Apart from a few low-yield by-products resulting from isomerization of the substrates, the carbonylated products obtained directly and exclusively are acetals.     

31P-NMR and X-ray studies of new rhodium(I) β-ketoiminato complexes Rh(R1C(O)CHC(NH)R2)(CO)(PZ3) where PZ3=PPh3, PCy3, P(OPh)3 or P(NC4H4)3

The substitution of the CO ligand in rhodium(I) β-ketoiminato complexes Rh(R₁{O,N}R₂)(CO)₂ ({O,N}=R₁C(O)CHC(NH)R₂; R₁, R₂=CF₃, Me, CMe₃ in several combinations) by phosphorus ligands PZ₃ (PZ₃=PCy₃, PPh₃, P(OPh)₃, P(NC₄H₄)₃) leads to Rh(R₁{O,N}R₂)(CO)(PZ₃) complexes characterised by ³¹P{¹H}-NMR and X-ray methods. The stronger σ-donor PZ₃ ligands (PZ₃=PCy₃, PPh₃) substitute almost exclusively the CO group trans to N, forming P-trans-to-N isomers. The complexes Rh(CF₃{O,N}Me)(CO)(PCy₃) (II), Rh(CF₃{O,N}CMe₃)(CO)(PCy₃) (III), Rh(CF₃{O,N}Me)(CO)(PPh₃) (IV) and Rh(CF₃{O,N}CMe)(CO)(PPh₃) (V) are of a square-planar geometry with a slight tetrahedral distortion around the rhodium atom in II, III and V. The RhP(PCy₃) bonds are slightly longer than the RhP(PPh₃) bonds. The reaction of stoichiometric amounts of the less basic P(OPh)₃ or P(NC₄H₄)₃ ligands leads to the formation of both isomers of the Rh(R₁{O,N}R₂)(CO)(P(OPh)₃) or Rh(R₁{O,N}R₂)(CO)(P(NC₄H₄)₃) complex in comparable yields. The RhP(P(OPh)₃) distance (2.195(2) Å) in the isomer of Rh(CF₃{O,N}CMe₃)(CO)(P(OPh)₃) with P(OPh)₃ coordinated trans to N (VI) is ca. 0.04 Å longer than in the isomer of that complex with P(OPh)₃ coordinated trans to O (VII). The CO substitution in Rh(R₁{O,N}R₂)(CO)₂ by PZ₃ ligands (PPh₃, PCy₃, P(OPh)₃) causes the shortening of the RhC(CO) bond by ca. 0.04 Å compared to Rh(CF₃{O,N}Me)(CO)₂ (I), making difficult the coordination of another PZ₃ ligand, especially one with stronger σ-donor properties. The more π-acceptor P(OPh)₃ ligands form bis-phosphito complexes and Rh(CF₃{O,N}CMe₃){P(OPh)₃}₂ (VIII) exhibits inequivalence of the two P(OPh)₃ ligands in solution (³¹P-NMR) as well as in solid form (X-ray).     

Metallorganische lewis-säuren; metallkomplexe mit schwach koordinierten anionischen liganden: XIII. Nachweis der koordination von tetrafluoroborat in carbonylmolybdän- und -wolfram-komplexen durch 19F- und 31P-NMR-spektroskopie

In the tetrafluoroborato complexes (η⁵-C₅H₅)(CO)₂LMFBF₃ (M = Mo, W; L = CO, PPh₃, P(OPh)₃) and (η⁵-C₉H₇)(CO)₃WFBF₃ the coordinated fluorine atom and the terminal F atoms of the BF₄ ligand can be distinguished by their ¹⁹F NMR signals. ¹⁹F and ³¹P NMR spectra of (η⁵-C₅H₅)(CO)₂P(OPh)₃WFBF₃ allow to establish cis → trans isomerization at elevated temperatures as well as rapid rotation of the coordinated BF₄ ligand.     

Katalytische isomerisierung von heptenen mit IrX(CO)L2

1-, 2-cis-, 2-trans-, and 3-trans-heptenes (C₇)are isomerized either very slowly or not at all with IrX(CO)L₂ at 80°C in toluene and under N₂. However, under the conditions of hydrogenation fast isomerisation takes place. With IrCl(CO)L₂ as catalyst the rate of isomerisation decreases the order: 1-C₇ ∼ 2-cis-C₇ > 3-trans-C₇ > 2-trans-C₇. This sequence is independent of the ligand L in lrCl(CO)L₂, however, with a particular isomer the rate of isomerisation is a function of L in the order L = PPh₃ > P(C₆H₁₁)3 > P(OPh)₃.     

Erratum

The reaction of Ir₆(CO)₁₆ with P(OPh)₃ in toluene yields Ir₆(CO)₁₂[P(OPh)₃]₄ which has been shown by X-ray diffraction to contain an octahedral cluster bearing four terminal P(OPh)₃ ligands, one face-bridging, three edge-bridging and eight terminal carbonyl groups. The carbonyl arrangement is different from that found in the analogous rhodium complex.     

Ligand substitution kinetics in M(CO)4(η-norbornadiene) complexes (M=Cr, Mo, W): displacement of norbornadiene by bis(diphenylphosphino)alkanes

The thermal substitution kinetics of norbornadiene (NBD) by bis(diphenylphosphino)alkanes (PP), (C₆H₅)₂P(CH₂)_nP(C₆H₅)₂ (n=1, 2, 3) in M(CO)₄(η^2:2-NBD) complexes (M=Cr, Mo, W), were studied by quantitative FT-IR spectroscopy. The reaction rate exhibits first-order dependence on the concentration of the starting complex, and the observed rate constant depends on the concentration of the leaving NBD ligand and on the concentration and the nature of the entering PP ligand. In the proposed mechanism there are two competing initial steps: an associative reaction involving the attachment of the entering PP ligand to the transition metal center and a dissociative reaction involving the stepwise detachment of the diolefin ligand from the transition metal center. A rate law is derived from the proposed mechanism. The activation parameters are obtained from the evaluation of the kinetic data. It is found that at higher concentrations of the entering ligand, the associative path is dominant, while at lower concentrations the contribution of the dissociative path becomes significant. Both the observed rate constant and the activation parameters show noticeable variation with the chain length of the diphosphine ligand.     

Synthesis of octahedral carbonyl complexes of manganese(I) with SCN or CN ligands. Crystal structure of fac-[SCNMn(CO)3(dppm)]

The complexes fac-[XMn(CO)₃(dppm)], cis,cis-[XMn(CO)₂(dppm)(P(OPh)₃)] and trans-[XMn(CO)(dppm)₂] with X = SCN or CN have been prepared from the corresponding bromocarbonyls and the salts AgX or KX, or, in the case of the di- and mono-carbonyls, from fac-[XMn(CO)₃(dppm)] with X = SCN or CN by thermal or photochemical CO substitution by the ligands P(OPh)₃ or dppm. The structure of fac-[SCNMn(CO)₃(dppm)] has been determined by X-ray diffraction. The crystals are monoclinic, space group P2₁/n, and the structure has been refined to R = 0.058 for 4123 reflexions measured in the range 2 ⩽ θ ⩽ 30 at room temperature. The cis,cis-[NCMn(CO)₂(dppm)(P(OPh)₃)] complex can be oxidized and subsequently reduced to the isomer trans-[NCMn(CO)₂(dppm)(P(OPh)₃)]. All the neutral cyanide complexes react readily with MeI and KPF₆ to give the corresponding methylisocyanide derivatives [Mn(CO)₂(dppm)(P(OPh)₃)(CNMe)]PF₆ and [Mn(CO)(dppm)₂(CNMe)]PF₆. The stereochemistries of the compounds is discussed in relation to the ³¹P NMR spectra.     

Eisen- und Mangankomplexe mit sauerstoff-, schwefel- und methylen-verbrückten Distibanen und mit Chlorodiphenylstiban als Liganden

Complexes of Iron and Manganese with Oxygen-, Sulfur-, and Methylene-bridged Distibines and with Chlorodiphenylstibine as Ligands The photochemical reaction of CO₃Fe[P(OPh)₃]₂ and of MeCpMn(CO)₃ with the stibines Ph₂SbCl and (Ph₂Sb)₂X (X = O, S and CH₂) yields mononuclear complexes (CO)₂[P(OPh)₃]₂FeL and °Cp(CO)₂MnL (L = Ph₂SbCl, (Ph₂Sb)₂X) and the stibine bridged binuclear complexes °CO)₂[P(OPh)₃]₂Fe{(Ph₂Sb)₂X}Fe(CO)₂[P(OPh)₃]₂ and °Cp(CO)₂Mn{(Ph₂Sb)₂X}Mn(CO)₂MeCp.     

Reduction products of dinuclear [Rh2Cl2(CO)2 {μ-(PhO)2PN(Et)P(OPh)2}2]. Crystal structure of [Rh2HgCl(μ-H)(CO)2 {μ-(PhO)2PN(Et)P(OPh)2}2]

Treatment of [Rh₂Cl₂(CO)₂ {μ-(PhO)₂PN(Et)P(OPh)₂}₂] with various reducing agents gives a number of products, the type depending on the conditions employed. The products isolated include [Rh₂(CO)₂{μ-(PhO)₂PN(Et)P(OPh)₂}₂], [Rh₂(CO)₃{μ-(PhO)₂PN(Et)P(OPh)₂}₂],and [Rh₂HgCl(μ-H)(CO)₂{μ-(PhO)₂PN(Et)P(OPh)₂}₂]; the structure of the last complex was determined by X-ray diffraction.     

Solvent and hydrogen effects in the isomerisation of pentenes catalysed by substituted derivatives of H4Ru4(CO)12

Summary The influence of the solvent on the homogeneous isomerisation of 1-pentene with H₄ Ru₄ (CO)₁₁ L, L=P(OEt)₃, P(OPh)₃, PPh₃, and with H₄Ru₄(CO)₁₀[P(OEt)₃]₂ is described. The initial rates decrease in the order: chlorobenzene > benzene > toluene > cyclohexane > mesitylene with H₄Ru₄(CO)₁₁P(OEt)₃ and similarly with H₄Ru₄(CO)₁₀[P(OEt)₃]₂. In the presence of H₄ Ru₄ (CO)]₁₁ P(OPh)₃ the isomerisation rates are approximately equal in toluene and cyclohexane but reversed with H₄ Ru₄ (CO)₁₁ PPh₃ . These results are interpreted by assuming the formation of the intermediate H₄Ru₄(CO)_11–nL_nS (n=1,2; S=solvent), which is affected by the nature of the solvent and by the different strengths of the Ru-S interaction. With the H₄Ru₄(CO)₁₁[P(OEt)₃] complex, molecular hydrogen at atmospheric pressure decreases the isomerising activity whereas with H₄Ru₄(CO)_12–n [P(OEt)₃]_n, n=2 or 4, the activity is increased. These changes are ascribed to a reversible modification of the catalyst with formation of a nonisolable species.     

Electrochemical reduction of transition metal-substituted silicon,germanium and tin derivatives: I. Cobalt or cobalt and iron complexes

The complexes Ph₃ECo(CO)₃L (E = Si, Ge; L = CO, PPh₃ P(OPh)₃) have been studied by electrochemistry. The reduction potential of these derivatives is less affected by the nature of the ligand L than in the case of [CO(CO)₃L]₂. The electrochemical reduction of the tin complexes [Co(CO)₄]_n[Fe(CO)₂Cp]_3?nSnCl (n = 1–3) showed that the formation of the radical anion occurred with tin-cobalt rather than tin-chloride bond rupture. Electrolysis of these tin derivatives did not give any distannane containing transition metal groups. However it can be noted that the Fe(CO)₂Cp group stabilized these tin complexes.