Novel rhodium(I) complexes with (2-hydroxyphenyl)diphenylphosphine ligand: catalytic properties and X-ray structures of Rh(OC6H4PPh2)(CO)(PPh3) and Rh(OC6H4PPh2){P(OPh)3}2 · 0.5C6H6 (original) (raw)
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Synthesis and Reactions of Cp-Linked Phosphine Complexes of Rhodium
Organometallics, 1998
The linked Cp ligand [C 5 H 4 SiMe 2 CH 2 PPh 2 ]has been used to synthesize several rhodium derivatives. Reaction with [RhClL 2 ] 2 , where L) C 2 H 4 , C 8 H 14 , or CO, gives (η 5 :η 1-C 5 H 4 SiMe 2-CH 2 PPh 2)Rh(L) complexes, which have been characterized by single-crystal X-ray diffraction. Reaction of the ethylene complex with CO or PMe 3 gives the carbonyl-and phosphinesubstituted derivatives, respectively. Irradiation of the ethylene complex in the presence of hydrogen gives a new binuclear polyhydride, also structurally characterized, in which the chelating ligand spans the two metal centers. Reaction of the ethylene complex with iodine leads to the formation of the diiodide (η 5 :η 1-C 5 H 4 SiMe 2 CH 2 PPh 2)RhI 2 , which in turn can be converted to the dihydride (η 5 :η 1-C 5 H 4 SiMe 2 CH 2 PPh 2)RhH 2 by reaction with NaAl(OCH 2-CH 2 OCH 3) 2 H 2. The reactivity of the dihydride toward C-H bond activation has been investigated. While benzene does not give a stable oxidative addition adduct, pentafluorobenzene yields (η 5 :η 1-C 5 H 4 SiMe 2 CH 2 PPh 2)Rh(C 6 F 5)H, which was structurally characterized as its chloro derivative. Reaction of the dihydride with C 6 F 6 gives the η 2 complex (η 5 :η 1-C 5 H 4 SiMe 2 CH 2 PPh 2)Rh(η 2-C 6 F 6), also structurally characterized.
Rhenium(I) Tricarbonyl Complexes with (2-Hydroxyphenyl)diphenylphosphine as PO Bidentate Ligand
Inorganic chemistry, 2017
In the present work, we investigated potential means to obtain neutral tricarbonyl mixed-ligand fac-[M(CO)3L(1)L(2)] complexes (M = Re, (99m)Tc) containing the (2-hydroxyphenyl)diphenylphosphine (POH) bidentate ligand (L(1)H) and a series of monodentate ligands (L(2)). First, fac-[Re(CO)3(PO)(H2O)], 1, was synthesized by reaction of POH and [Et4N]2[Re(CO)3Br3] in equimolar amounts in MeOH at room temperature. Interestingly, with excess of POH this reaction afforded fac-[Re(CO)3(PO)(POH)], 2, with POH operating both as a bidentate and as a monodentate ligand. Owing to the presence of the labile aqua ligand, which can be readily replaced by various monodentate ligands, 1 was further used as a precursor to generate a small library of the desired fac-[M(CO)3L(1)L(2)] complexes. Specifically, by reaction of triphenylphosphine (PPh3), imidazole (im), pyridine (py), cyclohexyl isocyanide (cisc), and tert-butyl isocyanide (tbi), the following products were readily obtained in excellent yiel...
Isostructural Phosphine−Phosphite Ligands in Rhodium-Catalyzed Asymmetric Hydroformylation
Organometallics, 2010
Isostructural phosphine-phosphite ligands 7-10 have been synthesized from the condensation of chiral 3,3 0-bis(trialkylsilyl)-2,2 0-bisnaphthol phosphorochloridites and phenol-phosphanes 3-6. These ligands were evaluated as chiral inducers in the rhodium-catalyzed asymmetric hydroformylation reaction (AHF) of vinyl acetate and a series of styrene derivatives. The highest enantioselectivity, 78% ee, was observed in the AHF of vinyl acetate using phenylphosphino-based ligand 10. A direct correlation between the enantioselectivity and the Hammett constant σ of the substituent in the substrates was found (4-Me-styrene, 15% ee; styrene, 23% ee; 4-Cl-styrene, 51% ee) under mild reaction conditions for phenylphosphole-based ligand 8. Several rhodium-hydride and rhodium-acyl complexes were prepared and characterized by HP-NMR and HP-IR spectroscopy. Rhodiumhydride complexes of the formula [HRh(L)(CO) 2 ] A with ligands 7, 8, and 10 were found to be highly conformationally fluxional in solution. The reaction of 4-Cl-styrene with rhodium-hydride complexes of ligands 7 and 8 gave the corresponding rhodium-acyl derivatives [(RCO)Rh(CO) 2 (L)] E. A comparative analysis of the spectroscopic properties of these rhodium-acyl complexes revealed that [(RCO)Rh(CO) 2 (7)] was more conformationally labile than [(RCO)Rh(CO) 2 (8)].
Rhodium(I) acetylacetonato complexes with functionalized phosphines
Journal of Organometallic Chemistry, 1998
Rhodium(I) complexes [Rh(acac)(CO)(PR 3)] with 1,3,5-triaza-7-phosphatricyclo[3.3.1.1 3,7 ]decane (tpa), tris(2-cyanoethyl)phosphine (cyep), tris(3-sodium sulfonatophenyl)phosphine (tppts), tris(o-methoxyphenyl)phosphine (ompp), tris(pmethoxyphenyl)phosphine (pmpp), tris(2,4,6-trimethoxyphenyl)phosphine (tmpp), PPh 2 (pyl), PPh(pyl) 2 and P(pyl) 3 (pyl =2-pyridyl) have been synthesized and characterized with 1 Hand 31 P-NMR and IR spectra. The measured 31 P coordination chemical shifts, Dl 31 P{ 1 H}, correlate well with w(CO). Differences in 1 H chemical shifts of methyl groups of acac ligand, Dl Me , depend both on steric and electronic properties of phosphine ligand. Thus Dl Me increases with decrease of Dl 31 P{ 1 H} and increases with increase of the cone angle of phosphine. Catalytic activity of complexes with tpa, cyep and tppts has been investigated. They are efficient catalysts for hydrogenation of C C and C O bonds, isomerization of alkenes and hydroformylation of alkenes. The mechanism of isomerization of allyl alcohol to propanal has been elucidated.
New Phosphacyclic Diphosphines for Rhodium-Catalyzed Hydroformylation
Organometallics, 1999
The use of phosphacyclic diphosphines based on the xanthene backbone as ligands in rhodium-catalyzed hydroformylation was studied. New phosphacyclic xantphos ligands with wide natural bite angles were synthesized, and a short, efficient route toward the synthesis of 10-chlorophenoxaphosphine and 10-chlorophenothiaphosphine was developed. The effect of the phosphacyclic moieties on the coordination chemistry in the (diphosphine)Rh(CO) 2 H complexes was investigated using NMR and IR spectroscopy. Both NMR and IR spectroscopy showed that the phosphacyclic xantphos ligands exhibit an enhanced preference for diequatorial (ee) chelation compared to the diphenylphosphino-substituted parent compound. In the hydroformylation of 1-octene the introduction of the phosphacyclic moieties leads to higher reaction rates. More importantly, the dibenzophospholyl-and phenoxaphosphinosubstituted xantphos ligands exhibit an unprecedented high activity and selectivity in the hydroformylation of trans 2-and 4-octene to linear nonanal. The high activities of the phosphacyclic xantphos ligands are explained by the lower phosphine basicity and the wider natural bite angles of the phosphacyclic ligands. The extraordinary high activity of the phenoxaphosphino-substituted xantphos ligand can be attributed to the 4-to 6-fold higher rate of CO dissociation compared to the other xantphos ligands. CO dissociation rates from the (diphosphine)Rh(CO) 2 H complexes were determined using 13 CO labeling in rapid-scan IR experiments.
Organometallics, 2002
The influence of electronic ligand properties on the catalyst performance in the rhodiumcatalyzed hydroformylation of alkenes has been investigated. Two bidentate phosphorus amidite and phosphinite ligands have been synthesized: 1,1′-biphenyl-2,2′-diyl-bis(dipyrrolylphosphoramidite) (3) and 1,1′-biphenyl-2,2′-diyloxy-bis(diphenylphosphinite) (4). Their monodentate analogues have also been studied: phenyldipyrrolylphosphoramidite (1) and phenyl diphenylphosphinite (2). These two sets of ligands have very similar steric properties but the amidites are much stronger π-acceptor ligands. Spectroscopic studies showed that under hydroformylation reaction conditions the monodentate ligands 1 and 2 form mixtures of HRhL 2 (CO) 2 and HRhL 3 (CO) complexes depending on the ligand and rhodium concentrations and the carbon monoxide pressure. Depending on the reaction conditions, the bidentate ligands 3 and 4 form mixtures of HRh(L∩L)(CO) 2 and HRh(L∩L)(L∩L′)(CO), where L∩L′ functions as a monodentate. All ligands have been tested in the hydroformylation reaction of oct-1-ene. A high π-acidity of the ligand resulted in a high rate of hydroformylation. The monodentate ligands 1 and 2 showed moderate selectivity for the linear aldehyde. The catalyst formed with the bidentate phosphorus amidite ligand 3 revealed high regioselectivity for the linear aldehyde (ratio l/b) ∼100) at a high rate together with a moderate selectivity for isomerization (∼7%). Deuterioformylation experiments of 1-hexene showed that the hydride (deuteride) migration is reversible in the hydroformylation system formed by 3. Surprisingly, both the linear rhodium-alkyl and the branched rhodium-alkyl complex undergo-hydride elimination. Furthermore, the 2-hexylrhodium intermediate regenerates more often monodeuterated 1-hexene than 2-hexene. The rhodium hydride species formed this way reacts relatively slowly with the excess of D 2 and as a result large amounts of monodeuterated heptanal (40% D 1 vs 60% D 2) and monodeuterated 1-hexene are formed. At higher conversions the latter gives trisdeuterated heptanal as well as bisdeuterated heptanal.
Organometallics, 1990
The crystal structure of the complex [(triphos)RhC1(C2H4)] (1) has been determined by X-ray methods (triphos = MeC(CH2PPh2),). The rhodium atom is coordinated to an ethylene molecule, a chlorine atom, and the triphos ligand, which occupies three fac positions of an octahedron. The Rh-C2H coordination exhibits a CC distance that is among the longest found in metal-ethylene structures (1.49 (4) A). Compound 1 is the starting point to synthesize a number of ethylene complexes of rhodium containing hydride or a-organyl coligands: [ (triphos)RhH(C2H4)], [(triphos)Rh(C2H5)(C2H4)], [ (triphos)Rh(CH,)(CzH4)], [ (triphos)Rh(C,H5)(C2H4)]. All of the ethylene complexes but 1 react with CO, forming u-acyl carbonyls of general formula [ (triphos)Rh(COR)(CO)] via the u-organyl carbonyls [ (triphos)Rh(R)(CO)] (R = CH,, C2H5, C6H5). Compound 1 reacts with CO, yielding the carbonyl [ (triphos)RhCl(CO)]. The hydrogenolysis reactions of the u-organyl ethylene complexes invariably give the trihydride [ (triphos)Rh(H),] and the corresponding hydrocarbon. In contrast, the a-acyl carbonyls and the u-organyl carbonyls react with H2 to form the hydride carbonyl [(triphos)RhH(CO)] and the corresponding hydrocarbon or aldehyde. Another excellent synthetic entry to organorhodium complexes of triphos is the +alkyne complex [ (triphos)Rh-(+DMAD)]BPh4 (DMAD = dimethyl acetylenedicarboxylate). This reacts with H2 to give the tetrahydride [ (triphos)RhH(j~H)~HRh(triphos)] (BPh4I2 and dimethyl succinate. Reaction of the q2-alkyne complex with CO affords the dicarbonyl [ (tripho~)Rh(CO)~]BPh~ which is converted into the ethylene carbonyl [ (triphos)Rh(CO)(C2H4)]BPh4 by treatment with Me,NO under a CzH4 atmosphere. The ethylene carbonyl is much better synthesized by protonation of [(triphos)RhH(CO)] under C2H4. In the absence of ethylene, the reaction gives [ (tripho~)Rh(H)~(CO)]BPh~ The hydrogenolysis and carbonylation reactions have been carried out at room temperature and 1 atm of H2 or CO. All of the compounds have been properly characterized by spectroscopic technique, including the computer simulation of the second-order 'H and 31P NMR spectra. The activities of all of the compounds as catalyst precursors for the homogeneous hydrogenation, isomerization, and hydroformylation reactons of alkenes and alkynes have been studied in detail. Particular attention has been focused on the substrates 1-hexene, &stilbene, diphenylacetylene, dimethyl maleate, and dimethyl acetylenedicarboxylate.