Polyphosphine Ligands Research Articles

Tetranuclear zigzag Ag4 and Ag2Pt2 complexes supported by rac-Ph2PCH2P(Ph)CH2P(Ph)CH2PPh2 (rac-dpmppm)

Reaction of AgOTf with a tetraphosphine, rac-bis[(diphenylphosphinomethyl) phenylphosphino]methane (rac-dpmppm), afforded [Ag4(rac-dpmppm)2](TfO)4 (3) which consists of zigzag-arrayed tetranuclear silver(I) ions supported by syn-arrangement of two enantiomeric (RR/SS) dpmppm ligands. Complex 3 readily reacted with XylNC (Xyl = 2,6-dimethylphenyl) to give [Ag4(rac-dpmppm)2(XylNC)2](TfO)4 (4), where two terminal isocyanides attach to the outer Ag sites. Complex 3 has been shown a good precursor for Pt-Ag-Ag-Pt mixed metal array as incubation of 3 with trans-[Pt(CCPh)2(PPh3)2] yielded [Ag2Pt2(CCPh)4(rac-dpmppm)2](TfO)2 (5). Two trans-Pt(CCPh)2 units are incorporated into the terminal positions in a site-selective fashion and the Pt-Ag-Ag-Pt tetranuclear core also adopts a zigzag array supported by syn-arrangement of two rac-dpmppm ligands. The d8 and d10 closed-shell mixed metal centers of 5 exhibited an intense photoluminescence at 534 nm, mainly from an unsymmetric triplet state generated by charge transfer transitions from ligand (acetylide π) to metal centers (Ag2 and PtAg s/pσ), 3LMCT, and to ligands (acetylide π* and dpmppm), 3LLCT. The present results provide fundamental and useful information to construct multinuclear closed-shell metal alignments by utilizing polyphosphine ligands.

Multinuclear Copper Hydride Complexes Supported by Polyphosphine Ligands

Copper hydride compounds have attracted interest in diverse fields as base metallic material in place of rare and noble metals, which have widely been utilized in hydrogenation catalysts, hydrogen storage, and electrochemical materials. Since the first report on the synthesis of copper hydride complex [Cu6H6(PPh3)6] in 1971, copper hydride reagents have been utilized in a variety of organic transformation. While well‐characterized copper hydride complexes have been long limited to a few examples, recently several research groups have reported the synthesis of phosphine‐stabilized copper hydride complexes with various metal‐frameworks and unique reactivity. Here we review recent progress on the synthesis and structures of copper hydride complexes supported by phosphine ligands, including di‐, tri‐, and tetraphosphines, and also describe their reactivity with CO2.

Ammonia Borane Dehydrogenation Catalyzed by (κ4-EP3)Co(H) [EP3 = E(CH2CH2PPh2)3; E = N, P] and H2 Evolution from Their Interaction with NH Acids.

Two Co(I) hydrides containing the tripodal polyphosphine ligand EP3, (κ4-EP3)Co(H) [E(CH2CH2PPh2)3; E = N (1), P (2)], have been exploited as ammonia borane (NH3BH3, AB) dehydrogenation catalysts in THF solution at T = 55 °C. The reaction has been analyzed experimentally through multinuclear (11B, 31P{1H}, 1H) NMR and IR spectroscopy, kinetic rate measurements, and kinetic isotope effect (KIE) determination with deuterated AB isotopologues. Both complexes are active in AB dehydrogenation, albeit with different rates and efficiency. While 1 releases 2 equiv of H2 per equivalent of AB in ca. 48 h, with concomitant borazine formation as the final "spent fuel", 2 produces 1 equiv of H2 only per equivalent of AB in the same reaction time, along with long-chain poly(aminoboranes) as insoluble byproducts. A DFT modeling of the first AB dehydrogenation step has been performed, at the M06//6-311++G** level of theory. The combination of the kinetic and computational data reveals that a simultaneous B-H/N-H activation occurs in the presence of 1, after a preliminary AB coordination to the metal center. In 2, no substrate coordination takes place, and the process is better defined as a sequential BH3/NH3 insertion process on the initially formed [Co]-NH2BH3 amidoborane complex. Finally, the reaction of 1 and 2 with NH-acids [AB and Me2NHBH3 (DMAB)] has been followed via VT-FTIR spectroscopy (in the -80 to +50 °C temperature range), with the aim of gaining a deeper experimental understanding of the dihydrogen bonding interactions that are at the origin of the observed H2 evolution.

Synthesis, structures and fluorescent properties of metal complexes based on polyphosphine ligands

Based on polyphosphine ligands, four complexes, [Cu2(pba)2(pipzdtc)]·2DMF (1), [Cu2(pbaa) (Et-dtc)2]·2DMF (2), [Cu2(pnaa) (Et-dtc)2] (3) and [Ag2(pnaa) (Et-dtc)2] ·2CH3CN (4) (pba = N,N-bis((diphenylphosphino)methyl)benzenamine, pbaa = N,N,N′,N'-tetrakis((di-phenylphosphino)methyl)benzene-1,4-diamine, pnaa = N,N,N′,N'-tetrakis((diphenylphosphino)- methyl)naphthalene-1,5-diamine, Et-dtc = N-ethyldithiocarbamate and pipzdtc = piperazine- 1,4-dicarbodithiolate), have been synthesized and characterized by IR, ESI-MS and X-ray crystal structure analysis. The structural analysis shows that each Cu+/Ag+ in complexes 1–4 is four coordinate P2S2, and adopts a distorted-tetrahedral geometry, and 1D infinite chain of complexes 2 and 4 is built by CH⋯π interaction of phenyl rings from pbaa and pnaa. All these indicate that the change of polyphosphine ligands and metal ions might be the key of construction of 1D infinite chain. Moreover, the emission spectra of complexes 2–4 in DMF solvent are also observed.

Synthesis, structures and properties of Ag+ complexes containing polyphosphine ligands with extended Ag⋯C, N-O⋯π and C-H⋯π interactions

Based on ligands of N,N-bis((diphenylphosphino)methyl)benzenamine (pba), 4-(4-(bis((diphenylphosphino)methyl)amino)benzyl)-N-((diphenylphosphino)methyl)benzenamine (dptp) and N,N,N′,N′-tetrakis((diphenylphosphino)methyl)benzene-1,4-diamine (pbaa), three new silver(I) complexes [Ag(pba)2]ClO4 (1), [Ag2(dptp)2](ClO4)2·2DMF (2) and [Ag4(pbaa)(NO3)4]n (3), have been synthesized and characterized. Structural analysis reveals that all of these complexes contain the 1D infinite chains, with different variations in the weak interactions. Complexes 1 and 2 are interconnected by intermolecular C-H⋯π interactions to form 1D infinite chains and 2D networks, and the ordered-layer-lattic ClO4− and DMF in 2 are between 2D networks. For 3, the pbaa ligand adopts a tetradentate coordination mode to link two adjacent stair-like [Ag4O4] cores resulting in a 1D chain, respectively, with Ag⋯C, N-O⋯π and C-H⋯π interactions. All these show that phosphine ligands play an important role in the construction of interesting topological structures with different types of the weak interactions.

Functionalized Tri‐ and Tetraphosphine Ligands as a General Approach for Controlled Implantation of Phosphorus Donors with a High Local Density in Immobilized Molecular Catalysts

AbstractSupported phosphine ligands are auxiliaries of topical academic and industrial interest in catalysis promoted by transition metals. However, both controlled implantation and controlled conformation of ligands should be achieved to produce immobilized catalysts that are able to structurally “copy” efficient homogeneous systems. We provide herein a general synthetic strategy for assembling a new class of branched tetra‐ and triphosphine ligands with a unique controlled rigid conformation, and thus providing a high local density of phosphorus atoms for extended coordination to the metal center. We prepared new functionalized cyclopentadienyl (Cp) salts to design polyphosphines that were “ready for immobilization”. These protected Cp fragments might also be of synthetic utility for generating other supported metallocenes. Tetra‐ and triphosphines were then formed and diversely functionalized for immobilization on virtually any kind of support. As evidenced by 31P NMR spectroscopy and the strong “through‐space” spin–spin TSJ(P,P) coupling observed between P atoms, these modified polyphosphines induce, when immobilized on a support, a high local concentration of phosphorus donors that are spatially very close to each other (3–5 Å). These functionalized ligands have been incorporated into polystyrene to give either soluble or insoluble polymers and on inorganic supports such as silica. We report the catalytic performance at 0.05–0.5 mol % low palladium loading of the resulting immobilized polyphosphine ligands. This study provides proof‐of‐concept of supported catalytic materials built from modular polyphosphines with a novel approach to structurally controlled polydentate heterogeneous catalysts.

Chemical Hydrogen Storage: Ammonia Borane Dehydrogenation Catalyzed by NP3Ruthenium Hydrides (NP3=N(CH2CH2PPh2)3)

Two novel RuII hydrides containing the tripodal polyphosphine ligand NP3 (N(CH2CH2PPh2)3) have been prepared and characterized: (κ4-NP3)Ru(H)2 (1) and [(κ4-NP3)Ru(H)(η2-H2)]BArCl4 (2; ArCl=3,5-dichlorophenyl, C6H3Cl2). The classical and nonclassical nature of the hydride ligand in 1 and 2, respectively, has been confirmed by solution NMR studies and single-crystal X-ray diffraction. The reaction of 1 and 2 with excess ammonia borane (NH3⋅BH3, AB) has been analyzed experimentally through variable-temperature multinuclear (11B, 31P, 1H) NMR spectroscopy, kinetic rate measurements, and kinetic isotope effect determination with deuterated AB isotopologues. Both complexes are active in AB dehydrogenation, with release of two H2 equivalents per AB equivalent, with concomitant polyborazylene and cyclic polyaminoborane formation as the final “spent fuel”. A DFT modeling of the AB first dehydrogenation step has been finally performed, at the M06//6-31G* level of theory. The combination of the kinetic and computational data reveals that the initial AB activation step is different for the two catalysts: a simultaneous BH/NH activation occurs in the presence of 1, whereas the NH activation only is the rate-determining step if 2 is employed as a catalyst.

Flexible Syntheses of Tripodal Phosphine Ligands 1,1,2-Tris(diarylphosphino)ethane and Their Ruthenium η5-C5Me5 Complexes

A series of four tripodal polyphosphine ligands (PAr2)2CHCH2PAr2 (1a–d) were synthesized and coordinated to ruthenium to produce the complexes [Ru(η5-C5Me5)((PAr2)2CHCH2PAr2)]PF6 (2a–d) (Ar = phenyl (a), p-tolyl (b), o-tolyl (c), m-xylyl (d)). The 1,1,2-tris(diarylphosphino)ethane compounds were generated in a novel trisubstitution reaction of diarylphosphorylacetaldehyde diethyl acetal, a useful synthetic precursor that was used previously for the synthesis of phosphonium dimers. The tridentate ligands were subsequently combined with the ruthenium(II) precursor Ru(η5-C5Me5)(1,5-COD)Cl, in order to probe the coordination geometry of 1a–d. The resulting complexes 2a–d displayed piano-stool type structures where the phosphine ligands were coordinated in a fac geometry. Despite the large steric bulk of the ligands, as well as the ring strain caused by the formation of a four-membered ring and two five-membered rings with the ruthenium center, complexes 2a–d were quite stable. The ruthenium salts were air and...

Gold(I) Chloride Complexes of Polyphosphine Ligands with Electron-Rich Arene Spacer: Gold–Arene Interactions

The reactions of Au(tht)Cl (tht = tetrahydrothiophene) with the electron-rich-arene-spacer-containing polyphosphine ligands N,N′-bis((diphenylphosphino)methyl)benzene-1,4-diamine (Dpba), N,N′-bis((...

Synthesis, structural characterization and luminescent properties of a series of Cu(i) complexes based on polyphosphine ligands

A series of Cu(I) complexes with a [Cu(NN)(PP)](+) moiety, [Cu(phen)(pba)](BF(4)) (1a), [Cu(2)(phen)(2)(pbaa)](BF(4))(2) (2a), [Cu(2)(phen)(2)(pnaa)](BF(4))(2) (3a), [Cu(2)(phen)(2)(pbbaa)](BF(4))(2) (4a), [Cu(dmp)(pba)](BF(4)) (1b), [Cu(2)(dmp)(2)(pbaa)](BF(4))(2) (2b), [Cu(2)(dmp)(2)(pnaa)](BF(4))(2) (3b) and [Cu(2)(dmp)(2)(pbbaa)](BF(4))(2) (4b) (phen = 1,10-phenanthroline, dmp = 2,9-dimethyl-1,10-phenanthroline, pba = N,N-bis((diphenylphosphino)methyl)benzenamine, pbaa = N,N,N',N'-tetrakis((diphenylphosphino)methyl)benzene-1,4-diamine, pnaa = N,N,N',N'-tetrakis((diphenylphosphino)methyl)naphthalene-1,5-diamine and pbbaa = N,N,N',N'-tetrakis((diphenylphosphino)methyl)biphenyl-4,4'-diamine), were rationally designed and synthesized. These complexes were characterized by (1)H and (31)P NMR, electrospray mass spectrometry, elemental analysis and X-ray crystal structure analysis. Introduction of different central arene spacers (phenyl, naphthyl, biphenyl) into ligands, resulting in the size variation of these complexes, aims to tune the photophysical properties of the complexes. Each Cu(I) ion in these complexes adopts a distorted tetrahedral geometry constructed by the chelating diimine and phosphine groups. Intermolecular C-H···π and/or π···π interactions are involved in the solid states. The dmp-containing complex exhibits better emission relative to the corresponding phen complex due to the steric encumbrance of bulky alkyl groups. Furthermore, for complexes with identical diimine but different phosphine ligands, the tendency of increased emission lifetime as well as blue-shifted emission in the solid state follows with the decrease in size of complexes. Intermolecular C-H···π interactions have an influence on the final solid state photophysical properties through vibrationally relaxed non-radiative energy transfer in the excited state. Smaller-sized complexes show better photophysical properties due to less vibrationally relaxed behavior related to flexible C-H···π bonds. Nevertheless, the tendency for increased quantum yield and emission lifetime, as well as blue-shifted emission in dilute solution goes with the increase in size of complexes. The central arene ring (phenyl, naphthyl or biphenyl) has an influence on the final photophysical properties. The larger the π-conjugated extension of central arene ring is, the better the photophysical properties of complex are. The rigid and large-sized complex 3b, with a high quantum yield and long lifetime, is the best luminophore among these complexes.

ChemInform Abstract: Stoichiometric and Catalytic Functionalization Reactions of Alkynes at Transition Metal Complexes Stabilized by Tripodal Polyphosphine Ligands

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Copper(I) Iodide Polyphosphine Adducts at Low Loading for Sonogashira Alkynylation of Demanding Halide Substrates: Ligand Exchange Study between Copper and Palladium

The prestabilization of copper iodide with a multidentate ferrocenyl phosphine ligand promotes the palladium-catalyzed cross-coupling of demanding halides with phenylacetylene in a selective way. Novel CuI-triphosphine adducts are described in the solid state and in solution. Their use allowed the introduction of the copper iodide cocatalyst in unprecedented low amounts (0.4 to 0.1 mol %) in systems also employing low amounts of “ligand-free” [PdII(η3-allyl)Cl]2 precursor (0.2 to 0.05 mol %). The scope of substrates is reported, and electronically or sterically deactivated bromides were efficiently coupled. Concerning aryl chlorides, electron-poor activated substrates were also coupled using this innovative low-metal-content catalytic system. Some rarely tackled mechanistic aspects are discussed herein. In particular, the transfer of ligand from copper to palladium monitored by NMR was found to be different depending on the polyphosphine ligand. The inhibition of diyne formation was also an interesting fe...

Synthesis, Structural Characterization and Luminescence Studies of Di‐ and Trinuclear Gold(I) Alkynyl‐phosphine Complexes

AbstractReactions of the polymer {AuIC2Ph}n with polyphosphine ligands [1,4‐bis(2‐diphenylphosphino‐1H‐imidazol‐1‐yl)‐benzene (dpib), 1,3,5‐tris(4‐diphenylphosphinophenyl)benzene (tppb), 2,2′‐bis(diphenylphosphanyl)‐4,4′‐bipyridine (dpbp), and 3,6‐bis(diphenylphosphanyl)pyridazine (dppz)] afforded four gold(I) alkynyl‐polyphosphine complexes [{AuC2Ph}2(μ‐dpib)] (1), [{AuC2Ph}3(μ3‐tppb)] (2), [{AuC2Ph}2(μ‐dpbp)] (3), and [{AuC2Ph}2(μ‐dppz)] (4) in nearly quantitative yield. The compounds obtained were characterized using elemental analysis, ESI‐MS, X‐ray crystallography, and polynuclear NMR spectroscopy. Intermolecular aurophilic interaction together with π–π and σ–π stacking build up the supramolecular 3D network of complex 3, whereas none of these intermolecular bondings were found in the crystal structures of compounds 1, 2, and 4. Complexes 1–4 are luminescent both in solution (CH2Cl2) and in solid state under laser irradiation (λex = 308 nm). In solution, the diphosphine complexes 1–4 display dual emission corresponding to ligand centered transitions (λem = 360–375 nm) along with weaker contribution from MLCT excited states at ca. 490 nm. The long wavelength component of the emission plays a dominant role in the solid state luminescence spectra of complexes 1, 3, and 4 (460, 544, 520 nm, respectively) whereas the triphosphine complex 2 shows dual luminescence (372 and 520 nm) with considerable contribution from ligand centered excited state.

Tripodal polyphosphine ligands as inductors of chelate ring-opening processes in mononuclear palladium(ii) and platinum(ii) compounds. The X-ray crystal structure of two derivatives containing dangling phosphorus

The reaction of NP(3) (tris[2-(diphenylphosphino)ethyl]amine and PP(3) (tris[2-(diphenylphosphino)ethyl]phosphine) with the five-coordinate complexes [PdCl(NP(3))]Cl (1) and [MX(PP(3))]X [M = Pd: X = Cl(2), Br(3), I(4); M = Pt: X = Cl(5), Br(6), I(7)], respectively, followed by (31)P{(1)H}NMR when X = Cl, led to the formation of unprecedented four-coordinate halides in a 1 : 2 metal to ligand ratio, [M(AP(3))(2)]X(2) [A = N, M = Pd: X = Cl(8); A = P, M = Pd: X = Cl(9), Br(10), I(11); A = P, M = Pt: X = Cl(12), Br(13), I (14)], containing reactive dangling phosphorus. Given the non characterised precursors [M(ONO(2))(PP(3))](NO(3))], the interaction between the heteronuclear species [MAg(NO(3))(3)(PP(3))] [M = Pd(15), Pt(16)] and PP(3) was explored. It was found that the addition of 1 equivalent of phosphine afforded [MAg(NO(3))(PP(3))(2)](NO(3))(2) [M = Pd(15*), Pt(16*)] containing Ag(I) bound to two dangling phosphorus while the reaction with 2 equivalents led to the complexes [M(PP(3))(2)](NO(3))(2) [M = Pd (17), Pt (18)] in coexistence with [Ag(2)(mu-PP(3))(2)](NO(3))(2). The fate of Ag(I) on the reaction of the mixed metal compounds with excess PP(3) consisted of preventing dissociation, observed in solution for halides, and acting as an assistant for crystallization. Colourless single crystals of 18 and 10, studied by X-ray diffraction, were afforded by reaction of 16 with 4 equivalents of PP(3) and from solutions of 10 in chloroform coexisting with red crystals of 3, respectively. The structures revealed the presence of dications [M(PP(3))(2)](2+) that show two five-membered chelate rings to M(II) in a square-planar arrangement and four uncoordinated phosphine arms with the counter anions being symmetrically placed at 4.431 (Br(-)) and 13.823 (NO(3)(-)) A from M(II) above and below its coordination, MP(4), plane. Complexes 9 and 12 were shown to undergo an interesting reactivity in solution versus group 11 monocations. The reactions consisted of conversions of the two five-membered chelate rings to M into three (structure I) or two (structure II) fused five-membered chelate rings, formation of species where Pt(II) retained its square-planar environment with the two dangling phosphine arms of each PP(3) bound to Cu(I) or Ag(I) (structure III) and complexes bearing distorted square-planar (P(2)MCl(2)) and presumably tetrahedral (AuP(4)+ P(2)AuCl(2)) arrangements (structure IV). The processes with Ag(I) salts also gave mixtures of I+III (chloride and nitrate) or II+III (nitrate).

Tripodal polyphosphine ligands in silver (I) coordination chemistry: Mononuclear cf. polynuclear complex dependence vis-a-vis counterion and ligand to metal ratio

1:2, 1:1, 3:2 and 6:2 AgX:L adducts (where L is a tridentate phosphine, in detail: 1,1,1-tris(diphenylphosphinomethyl)ethane (Me-triphos) and bis(2-diphenylphosphinoethyl)phenylphosphine (Ph-triphos), X = O 3SCF 3, O 3SCH 3, BF 4 or O 2CCF 3) have been synthesized and characterized by IR, NMR ( 1H, 31P and 19F) and ESI MS spectroscopy. The stoichiometry of the complexes is strongly dependent on the ligand to metal ratio employed and also on the nature of the counterion. 31P NMR (solution) data also show the complexes existing in solution, in some cases, however, disproportionating to adducts of different nuclearity. Oligonuclear species have been detected through ESI MS spectroscopy that has been demonstrated as a powerful tool for the identification of the solution species. AgBF 4:Me-triphos (1:2) has been structurally characterized as [Ag( P, P′-Me-triphos) 2](BF 4) · H 2O · 7/2 MeOH, while Ag(O 3SCF 3): Ph-triphos: H 2O (6:2:4) is a spectacular two-dimensional polymer.

New synthetic route to polyphosphine ligands bearing 1,2,4,5-tetrakis(phosphino)benzene framework: structural characterizations of 1,4-(PPh 2) 2-2,5-(PR 2) 2-C 6F 2 (R = Ph, iPr, Et)

Reactions of 1,4-dibromo-2,5-difluorobenzene with two equivalents of lithium diisopropylamide at low temperature ( T < −90 °C) followed by a quench with a slight excess of ClPPh 2 afford 1,4-dibromo-2,5-bis(diphenylphosphino)-3,6-difluorobenzene ( 1) in good yields. Reacting 1 with two equivalents of BuLi followed by a quench with a slight excess of ClPR 2 yield novel 1,2,4,5-tetrakis(phosphino)-3,6-difluorobenzenes 1,4-(PPh 2) 2-2,5-(PR 2) 2-C 6F 2 (R = Ph ( 2a); R = i Pr ( 2b); R = Et ( 2c)) in moderate yields. Compounds 1 and 2a– c were characterized by multinuclear NMR spectroscopy and elemental analyses. In addition, molecular structures of 2a– c have been determined by single crystal X-ray crystallography. Phosphorus atoms of PPh 2/PR 2 substituents in 2a– c are displaced from the plane of the central phenyl ring due to steric interactions with neighboring groups.

Hydrogenation of Indole by Phosphine-Modified Rhodium and Ruthenium Catalysts

The selective hydrogenation of indole (IN) to indoline (INE) by rhodium and ruthenium catalysts modified with the tripodal polyphosphine ligand MeC(CH2PPh2)3 (triphos) has been investigated in the homogeneous phase. Both [Rh(DMAD)(triphos)]PF6 (DMAD = dimethyl acetylenedicarboxylate) and [Ru(MeCN)3(triphos)](SO3CF3)2 have been found to generate effective catalysts for the conversion of IN to INE in THF in the presence of triflic acid. The protic acid is required to generate the 3H-indolium cation, which contains a localized CN bond. The rhodium precursor was more efficient than the ruthenium species and allowed for hydrogenation of the substrate even at 60 °C with turnover frequencies as high as 100. Catalytic experiments in autoclaves and in high-pressure sapphire NMR tubes have provided valuable information on the hydrogenation mechanism of IN.

ChemInform Abstract: Design and Synthesis of Macrocyclic Multidentate Polyphosphine Ligands with Nanosized Cavities for the Encapsulation of Vertex‐Sharing Polyicosahedral Mixed‐Metal Nanoclusters

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Hydrogenation of Quinoline by Rhodium Catalysts Modified with the Tripodal Polyphosphine Ligand MeC(CH2PPh2)3

As part of our modelling studies of the hydrodenitrogenation of N-heterocycles contained in raw oil materials, we investigated the selective hydrogenation of quinoline to 1,2,3,4-tetrahydroquinoline by rhodium catalysts modified with the tripodal polyphosphane ligand MeC(CH2PPh2)3. Experiments in standard autoclaves and in high-pressure sapphire NMR tubes, kinetic and isotope labelling studies, and independent reactions with isolated compounds have contributed to the elucidation of the catalytic mechanism as well as identification of the electronic requisites of the metal catalyst for selective and efficient hydrogenation.

Hydrogenation of Quinoline by Rhodium Catalysts Modified with the Tripodal Polyphosphine Ligand MeC(CH2PPh2)3

Hydrogenation of Quinoline by Rhodium Catalysts Modified with the Tripodal Polyphosphine Ligand MeC(CH2PPh2)3