cas 12092-47-6, Chloro(1,5-cyclooctadiene)rhodium(I) dimer

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Application of microwave dielectric loss heating effects for the rapid and convenient synthesis of organometallic compounds
Diolefin-rhodium(I) and -iridium(I) complexes have been synthesised in a sealed Teflon container by use of microwave heating.The products are obtained in excellent yields and in less than 1 minute compared with many hours by conventional reflux techniques
Baghurst, David R.,Mingos, D. Michael P.,Watson, Michael J.
p. C43 - C45
(1989)
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Design and application of a reflux modification for the synthesis of organometallic compounds using microwave dielectric loss heating effects
A commercially available microwave oven has been modified so that synthese involving the refluxing of organic solvents can be safely and conveniently undertaken.The application of this technique for accelerating the rates of reactions leading to the synth
Baghurst, David R.,Mingos, D. Michael P.
p. C57 - C60
(1990)
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Immobilized chiral rhodium nanoparticles stabilized by chiral P-ligands as efficient catalysts for the enantioselective hydrogenation of 1-phenyl-1,2-propanedione
This work reports the efficient synthesis of enantio-enriched alcohols by asymmetric hydrogenation of 1-phenyl-1,2-propanedione using chiral nanoparticles (NPs) supported on SiO2. The chiral catalysts were synthesized by reducing the [Rh(μ?OCH3)(C8H12)]2 precursor under H2 in the presence of P-chiral ligands as stabilizers and SiO2 as support. Synthesis of catalysts in mild conditions was performed from labile organometallic precursor and chiral ligands provided small and well defined chiral nanoparticles (≤ 3 nm). The catalysts were characterized by XPS, HR-TEM, EDS, XRD and N2 physisorption isotherm. The physical chemical properties of the materials were correlated with the catalytic results obtained in the asymmetric hydrogenation of 1-phenyl-1,2-propanedione. In 1-phenyl-1,2-propanedione hydrogenation the best results using chiral catalysts allowed 98% conversion and enantiomeric excess of 67% to (R)-1-hydroxy-1-phenyl-propan-2-one and 59% for (R)-2-hydroxy-1-phenylpropan-1-one. Catalyst recycling studies revealed that chiral nanoparticles immobilized on SiO2 are stable. These catalysts do not need extra amount of chiral modifier or inducer added in situ and could be reused without loss of enantioselectivity.
Ruiz, Doris,M?ki-Arvela, P?ivi,Aho, Atte,Chiment?o, Ricardo,Claver, Carmen,Godard, Cyril,Fierro, José L.G.,Murzin, Dmitry Yu.
(2019)
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Synthesis of M2Rh2 Bis(μ3-carbon dioxide) complexes from the reaction between [Rh(OH) (η4-COD)]2 and cationic metal carbonyls
The M2Rh2 bis(μ3-CO2) complexes [Cp*(CO)(NO)Re(CO2)Rh(η4-cod)]2 (1) and [Cp*(CO)2-MCO2Rh(η4-cod)] 2, M = Fe (2) and Ru (3), were synthesized in moderate to high yields from treating [Rh(OH)(η4-cod)]2 (cod = 1,5-cyclooctadiene) with the carbonyl salts Cp*(L)(CO)2M+ (L = CO, M = Fe, Ru; L = NO, M = Re) and a base. [An alternative synthesis of 1 and its crystallographic structure determination has been reported.] Although details on using several bases in the synthesis of 2 are reported, the use of volatile EtMe2N in excess as the base is especially useful. IR and NMR spectral data are in accord with a M2Rh2 bis(μ3-CO2) core for 2 and 3: they retain two μ3-[η1-C(M):η1-O(Rh):η 1-O′(Rh′)] carboxylate ligands that resemble those that were found for 1 and the Rh(I) carboxylates [(RCO2)Rh(diene)]2. Complexes 2 and 3 with their open-book structures are not fluxional at room temperature. Complex 2, its norbornadiene analogue, [Cp*(CO)2FeCO2Rh(η4-nbd)]2 (4), and their 13C-labeled derivatives also are accessible from reactions of Cp*(CO)2FeCO2K [or Cp*(CO)2-Fe13CO2K] with [Rh(OSO2CF3)(η4-cod)x. [Cp*(CO)2Fe(13CO2)Rh(η 4-diene)]2 [diene = cod (2-13C); nbd (4-13C)] underwent carboxylate-carbonyl label shuttle to yield 1:1 mixtures of [Cp*(CO)(13CO)FeCO2Rh(diene)]2 (2a-C13) and 4a-C13. IR spectral assignments for the metallocarboxylate νOCO absorptions are also presented.
Tetrick, Stephen M.,Xu, Chongfu,Pinkes, John R.,Cutler, Alan R.
p. 1861 - 1867
(1998)
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A New Reaction Vessel for Accelerated Syntheses using Microwave Dielectric Super-heating Effects
Using a thick-walled glass reaction vessel a number of transition-metal organometallic and co-ordination compounds have been synthesised using microwave dielectric super-heating effects.Super-heating by 40-60 deg C is maintained by controlling the pressure at 10 atm and results in a decrease in the reaction time required for conventional reflux reactions by a factor of ca. 102.Full details of the design of the apparatus, the modification of a conventional microwave oven and the electrical circuitry for the pressure control are provided.
Baghurst, David R.,Mingos, D. Michael P.
p. 1151 - 1156
(1992)
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Rhodium complexes of a chelating bisphosphoniobenzophospholide cation
The 1-(diphenyl(2-diphenylphosphinoethyl)phosphonio)-3-triphenylphosphoniobenzo[c]ph ospholide cation 1 reacts with [RhCl(C2H4)2]2 to form a dinuclear chelate complex, [RhCl(κ2-P(?2), P′(?)-1)]2 (5). Treatment of 5 with PPh3 affords mononuclear [RhCl(PPh3)(κ2- P(?2),P′(?3)-1)] (8), whereas reaction with 1,5-cyclooctadiene proceeds via cleavage of the Cl bridges to give [RhCl(cod)(κ-P(?3)-1)] (6). The chelating binding mode of 1 can be reconstituted by abstraction of chloride with TlOTf to give the dicationic complex [Rh(cod)(κ2-P(?2),P′(?3 )-1)]2+ (7). All complexes have been characterized by 1H, 31P, and 103Rh NMR spectroscopy, and 5[BPh4]2 was characterized as well by single-crystal X-ray diffraction. The structural parameters and metal NMR data confirm the different electronic properties of the two types of phosphorus centers in 1 and support in particular the assumption of distinct ?-acceptor character for the ?2-P atom, which should render the complexes potentially interesting precatalysts for hydroformylation. In accord with this hypothesis, complexes 5[BPh4]2 and 7[BPh4]2 display good activities and chemoselectivities as catalysts for the hydroformylation of 1-hexene at room temperature, even though the regioselectivities for n-aldehydes are low.
Haep, Stefan,Nieger, Martin,Gudat, Dietrich,Betke-Hornfeck, Michael,Schramm, Daniel
p. 2679 - 2685
(2008/10/08)

Reactions of [RhCl(diene)]2 with Bi- and terdentate nitrogen ligands. X-ray structures of five-coordinate complexes
Reaction of [RhCl(diene)]2 (diene = 1,5-cyclooctadiene (COD) or bicyclo[2.2.1] hepta-2,5-diene (NBD)) with the N-N-N nitrogen ligands 2,6-(C(R1)=N-R2)2C5H3N in CD2Cl2 or CH2Cl2 yielded the five-coordinate complexes [RhCl(2,6-(C(H)=N-R2)2C5H3N)(diene)] (diene = NBD; R2 = i-Pr, t-Bu, and p-anisyl), which has been isolated for NBD but not for COD. A single-crystal X-ray determination showed that [RhCl(2,6-(C(H)=N-p-anisyl)2C5H3N)(NBD)] has a distorted trigonal bipyramidal configuration with the pyridyl N-atom, one imine N-atom, and one alkene double bond in the equatorial plane, while the second alkene bond and the chloride atom occupy the axial positions. This conformation containing one noncoordinated imine moiety is clearly retained at 183 K in CD2Cl2, as is also the case for the other complexes. For the COD complexes, the reaction is more complicated, as the intermediates that are observed depend on the substituents R1 and R2 of the N-N-N nitrogen ligand. The five-coordinate complexes [RhCl(2,6-(C(R1)=N-R2)2C5H 3N)(COD)] could be observed at low temperatures for R1 = H and R2 = i-Pr, t-Bu, and p-anisyl, while for R1 = Me and R2 = p-anisyl, this intermediate could not be observed; instead, [Rh(2,6-(C(Me)=N-p-anisyl)2C5H3N) 2]+Cl- was found, which shows the presence of one N-N-N ligand bonded as a bidentate ligand and one N-N-N ligand bonded as a terdentate ligand at low temperatures. Further reaction of [Rh(2,6-(C(Me)=N-p-anisyl)2C5H3N) 2]+Cl- with [RhCl-(COD)]2 afforded [RhCl(2,6-(C(Me)=N-p-anisyl)2C5H3N)] and subsequently, via oxidative addition of CD2Cl2, the complex [RhCl2(CD2Cl)(2,6-(C(Me)=N-p-anisyl)2C 5H3N)]. The dynamic properties of the five-coordinate diene complexes [RhCl(2-(C(H)=N-R2)-6-(Me)-C5H3N)(NBD)] (R2 = i-Pr, t-Bu, and p-anisyl), which contain N-N nitrogen ligands, and of the new complexes [Rh(2-(C(H)=N-R2)-6-(Me)C5H3N)(NBD)]OTf (R2 = i-Pr, t-Bu, and p-anisyl) and of [Rh(2,2′-bipyrimidine)(NBD)]OTf have been investigated. A single-crystal X-ray determination of [RhCl(2-(C(H)=N-i-Pr)-6-(Me)C5H3N)(NBD)] showed structural features which are analogous to those of [RhCl(2,6-(C(H)=N-p-anisyl)2C5H3N)(NBD)].
Haarman, Hendrikus F.,Bregman, Frank R.,Ernsting, Jan-Meine,Veldman, Nora,Spek, Anthony L.,Vrieze, Kees
p. 54 - 67
(2008/10/08)

Polyoxoanion-supported catalyst precursors. Synthesis and characterization of the iridium(I) and rhodium(I) precatalysts [(n-C4H9)4N]5Na 3[(1,5-COD)M·P2W15Nb3O 62] (M = Ir, Rh)
The reaction of the triniobium-substituted polyoxometalate [(n-C4H9)4N]9P2W 15Nb3O62 with an equimolar amount of [Ir(1,5-COD)(CH3CN)2]BF4 or [Rh(1,5-COD)(CH3CN)2]BF4 (1,5-COD = 1,5-cyclooctadiene) leads to the formation of the air-sensitive polyoxometalate-supported organometallic complexes [(1,5-COD)IrP2W15Nb3O62] 8-, 1, and [(1,5-COD)Rh·P2W15Nb3O 62]8-, 2. These complexes were isolated as their mixed 5[(n-C4H9)4N]+/3Na+ salts and have been characterized by 1H, 13C, 31P, and 183W NMR spectroscopy as well as IR spectroscopy, sedimentation-equilibrium molecular-weight measurements, and complete elemental analyses. Additional studies of 1 by 17O NMR demonstrate that the iridium binds in overall average C3v (pseudo) symmetry to the Nb3O93- minisurface (pseudo due to the 2-fold axis in 1,5-COD and thus the local Cs symmetry at iridium). For 2, the results of the 17O NMR studies are definitive in showing that 2 can also be successfully 17O-enriched in the niobium-oxygen sites. However, the 17O NMR data subsequently acquired for 2 require the formulation of two or more (possibly rapidly interconverting) support-site isomers in solution. These 17O NMR results provide direct evidence for the M-ONb2 bonding between [(1,5-COD)M]+ (M = Ir, Rh) and P2W15Nb3O629- in solution, where catalysis beginning with 1 and 2 as a precatalyst has been demonstrated.
Pohl, Matthias,Lyon, David K.,Mizuno, Noritaka,Nomiya, Kenji,Finke, Richard G.
p. 1413 - 1429
(2008/10/08)

Synthesis of the Mixed-metal Clusters ; Reactions of > (R = Ph or Et) and Crystal Structure of 3-Au(PPh3)>>
Treatment of the pentaruthenium salt 2 with an excess of (cod = cycloocta-1,5-diene) yielded the monoanion (1-) which has been isolated as its (1+) salt 1.Reaction of the monoanion with HBF4*Et2O gave the hydrido derivative 2.Compound 1 reacted with the gold salts Cl and Cl, respectively, to yield the cluster compounds > 3 and > 4.Compound 3 crystallises in the triclinic space group P (no. 2) with a = 15.993(3), b = 9.728(2), c = 13.900(3) Angstroem, α = 90.29(2), β = 99.97(2), γ = 88.36(2) deg.The metal core geometry consists of a central Ru5Rh octahedron with one Ru3 face capped by a μ3-Au(PPh3) fragment .The reactions of 3 and 4 with norbornadiene, PPh3 and P(OMe)3 are reported.
Adatia, Trushar,Curtis, Hilary,Johnson, Brian F. G.,Lewis, Jack,McPartlin, Mary,Morris, Jill
p. 3069 - 3074
(2007/10/02)

Steric effects of the 2-(diphenylphosphino)-6-methoxypyridine short-bite bridging ligand in the synthesis of binuclear complexes. Crystal and molecular structure of [Rh2Cu(CO)2(Ph2PPyOMe) 2(μ-Cl)2]BF4·CH2Cl 2
Treatment of [Rh(COD)(μ-Cl)]2 (COD = cycloocta-1,5-diene) with 2-(diphenylphosphino)-6-methoxypyridine (Ph2PPyOMe) in benzene solution yielded the complex [Rh(COD)(Ph2PPyOMe)Cl] (1), in which Ph2PPyOMe acts as an η1 P-bonded ligand. The COD ligand was easily displaced when CO was bubbled into a CH2Cl2 solution of 1, and the presence in solution of cis-[Rh(CO)2(Ph2PPyOMe)Cl] (2) was established by IR and NMR spectroscopy. By the addition of Ph2PPyOMe to a CH2Cl2 solution containing 2 (molar ratio 1:1) or [Rh(CO)2(μ-Cl)]2 (molar ratio 4:1), trans-[Rh(CO)(Ph2PPyOMe)2Cl] (3) was obtained. The lack of formation in these reactions of the A-frame complex [Rh2(μ-CO)(Ph2PPyOMe)2Cl2], as was observed in the analogous reactions with 2-(diphenylphosphino)pyridine (Ph2PPy), is discussed. The reaction of 3 with [Cu(NCCH3)4]BF4, in CH2Cl2 solution, gave nearly quantitatively the complex [Rh2Cu(CO)2(Ph2PPyOMe) 2(μ-Cl)2]BF4·CH2Cl 2 (4), whose structure was established by an X-ray diffraction study. Attempts to obtain a Rh2Au complex, analogous to 4, failed. Crystals of 4 are monoclinic, of space group P21/a with Z = 4 in a unit cell of dimensions a = 32.852 (8) A?, b = 10.452 (4) A?, c = 12.945 (5) A?, and β = 97.17 (2)°. The structure was solved from diffractometric data by Patterson and Fourier methods and refined by full-matrix least-squares techniques on the basis of 4842 observed reflections to R and Rw values of 0.0500 and 0.0661, respectively. The cationic complex of 4 is a trinuclear Rh2Cu species containing two rhodium atoms linked by two bridging chloride ligands; the CO and the Ph2PPyOMe (P-bonded to Rh) ligands complete the coordination of each rhodium center. The two CO ligands are mutually trans. The copper center is almost linearly coordinated by the pyridine nitrogen atoms of the Ph2PPyOMe ligands. The copper and rhodium atoms are not involved in a metal-metal bond. The reaction of 1 with [AuPPh3]PF6 afforded [Rh(COD)(μ-C l)]2 and [Au(PPh3)(Ph2PPyOMe)]PF6 (6). Transfer of the Ph2PPyOMe ligand from one metal center to another occurred also in the reactions of 1 with cis-[Pd(CNtBu)2Cl2] and [Pd(COD)Cl2]. The reaction products were [Rh(CO)2(μ-Cl)]2 and respectively cis-[Pd(CNtBu)(Ph2PPyOMe)Cl2] (7) and [Pd(Ph2PPyOMe)Cl(μ-Cl)]2 (8), Ph2PPyOMe acting as an η1 P-bonded ligand in the last two. The effect of the small bite angle of the Ph2PPyOMe ligand on the pathway of these reactions is discussed, and a comparison with the results of analogous reactions of complexes containing the Ph2PPy ligand is made.
Arena, Carmela Grazia,Faraone, Felice,Lanfranchi, Maurizio,Rotondo, Enrico,Tiripicchio, Antonio
p. 4797 - 4802
(2008/10/08)

Synthesis and X-ray structural characterization of heterobimetallic rhodium-platinum and rhodium-palladium benzothiazole-2-thiolate compounds. The first binuclear complexes having two short-bite anionic bridging ligands in a trans disposition
Reactions of the binuclear complex [Rh(μ-bzta)(CO)(PPh3)]2 (1) (bzta = benzothiazole-2-thiolate) with the complexes MCl2(cod) (M = Pd, Pt; cod = 1,5-cyclooctadiene) afford the new diamagnetic heterobinuclear compounds (Ph3P)M(μ-bzta)2RhCl(CO) [M = Pt (2), Pd (3)] as well as MCl2(PPh3)2 and [Rh(μ-Cl)(cod)]2 through a complicated process. The new mononuclear complexes trans-Pt(bzta)2(PPh3)2 and trans-PtH(bzta)(PPh3)2 react with [Rh(μ-Cl)(CO)2]2 to give (Ph3P)Pt(μ-bzta)2RhCl(CO) (2) in moderate or low yield. Characteristic features of the structures of compounds 2 and 3 are revealed by their IR and 1H and 31P NMR spectra. 2 crystallizes with a molecule of CH2Cl2 in the triclinic space group P1 with a = 11.425 (1) A?, b = 11.819 (1) A?, c = 14.393 (1) A?, α = 107.88 (1)°, β = 99.85 (1)°, γ = 93.43 (1)°, V = 1809.3 (3) A?3, and Z = 2. On the basis of 4546 independent observations and 332 parameters, the structure was refined to R = 0.0224 and Rw = 0.0247. The metal centers, which are joined by a short metal-metal bond [2.6266 (4) A?], are bridged in a mutually trans and head-to-head fashion by the two benzothiazole-2-thioiate groups, which are bound to platinum through the exocyclic sulfur and to rhodium through the nitrogen. One triphenylphosphine on platinum, and chloro and carbonyl ligands on rhodium, complete the square planar and square pyramidal coordinations around the platinum and rhodium atoms, respectively.
Ciriano, Miguel A.,Pérez-Torrente, Jesús J.,Lahoz, Fernando J.,Oro, Luis A.
p. 969 - 974
(2008/10/08)

Heterobinuclear IrRh, RuRh and RuIr Complexes with Pyrazolate Bridging Ligands: Reactivity towards Chelating Diphosphines; Crystal Structure of BPh4*0.5MeOH
Complexes of general formula 1-5 and i-p)Ru(μ-pz)(μ-Cl)2Rh(cod)> 7 were prepared starting from mononuclear acetylacetonate and pyrazole or pyrazolate-containing moieties.Complexes 1-5 react with CO yielding derivatives 8-12.Complexes 13 and i-p)ClRu(μ-pz)2Ir(CO)2> 12 react with NaX to give (X = I; 14; or N3, 15) and i-p)Ru(μ-pz)2IrX(CO)2> (X = Br, 16; or I, 17.The dicarbonyl compound 10 and i-p)ClRu(μ-pz)2M'(CO)2> (M' = Rh, 11; or Ir, 12) react with diphosphines (L-L) or 1,2-bis(diphenylarsino)ethane (dpae) and NaBPh4 or AgBF4 affording cationic complexes >A 23-31 A = BPh4 or BF4 (not all possible combinations)>.In this reaction intermediates >A have been isolated in some cases.The crystal structure of one of these BPh4*0.5MeOH 19 has been determined by X-ray diffraction methods.Crystals are monoclinic, space group P21/c, a = 15.996(2), b = 22.199(4), c = 18.874(3) Angstroem, β = 115.04(1) deg and Z = 4.The complex cation consists of two iridium atoms bridged by two pyrazolates and one ketonic carbonyl group.An η5-C5Me5 ligand, a chelate dppen and a terminal CO group complete the co-ordination spheres of the iridium atoms, which are separated by 3.440(5) Angstroem.
Carmona, Daniel,Ferrer, Joaquina,Lahoz, Fernando J.,Oro, Luis A.,Reyes, Josefa,Esteban, Montserrat
p. 2811 - 2820
(2007/10/02)

Steric effects of the 2-(diphenylphosphino)pyridine bridging ligand in the synthesis of binuclear RhPd complexes. Crystal structures of [(CNtBu)2Cl2Rh(μ-Ph 2PPy)Pd(μ-Cl)]2 and [(C8H12)Rh(μ-Cl)(μ-Ph2PPy)PdCl 2]
The reaction of [Rh(COD)(μ-Cl)]2 (COD = cycloocta-1,5-diene) with 2-(diphenylphosphino)pyridine (Ph2PPy), in benzene solution, gave the complex [Rh(COD)(Ph2PPy)Cl], (1) in which the Ph2PPy acts as monodentate P-bonded ligand. The P,N chelation of the Ph2PPy to the rhodium(I) center to give the cationic complex [Rh(COD)(Ph2PPy)]X (X = ClO4, 2a; X = PF6,2b) was achieved by treating 1 with AgClO4 or AgPF6. The uncoordinated pyridine nitrogen atom of 1 was protonated by HPF6, giving [Rh-(COD)(Ph2PPyH)Cl]PF6 (3). The known A-frame complex [Rh2Cl2(Ph2PPy)2(μ-CO)] was obtained by bubbling CO into a dichloromethane solution of 1. In the presence of PPh3, the reaction of 1 with CO gave the compound [Rh(CO)(PPh3)(Ph2PPy)Cl] (4). The reaction of 1 with cis-[Pd(CNtBu)2Cl2], in CH2Cl2 solution, gave nearly quantitatively the tetranuclear formal RhIIPdI complex {[(tBuNC)2Cl2Rh(μ-Ph 2PPy)Pd(μ-Cl)]2} (5) whose structure was also established by X-ray diffraction methods. Compound 5 was also obtained by adding in succession Ph2PPy and [Rh(COD)(μ-Cl)]2, in the appropriate stoichiometric ratio, to a CH2Cl2 solution of cis-[Pd(CNtBu)2Cl2]. The addition of Ph2PPy to a CH2Cl2 solution of cis-[Pd(CNtBu)2Cl2] afforded the mixed isocyanide-tertiary phosphine complex cis-[Pd(CNtBu)(Ph2PPy)Cl2] (6). Crystals of 5 are monoclinic, space group P21/a with Z = 2 in a unit cell of dimensions a = 19.420 (8) A?, b = 11.700 (5) A?, c = 15.006 (6) A?, and β = 110.80 (2)°. The structure has been solved from diffractometer data by Patterson and Fourier methods and refined by full-matrix least squares on the basis of 1959 observed reflections to R and Rw values of 0.0738 and 0.0987, respectively. The tetranuclear complex is centrosymmetric with the inversion center relating two PdRh dimeric units in which the Pd-Rh separation is 2.612 (3) A?. Two Cl atoms asymmetrically bridge the Pd atoms. The Ph2PPy ligand also acts as a bridge being bound to the Pd atom through the P atom and to the Rh atom through the pyridine N atom. The reaction of 1 with {Pd[CH2C(CH3)CH2]Cl}2, in CH2Cl2 solution, gave quantitatively the palladium-allyl complex {Pd[CH2C(CH3)CH2](Ph2PPy)Cl} (9), together with [Rh(COD)(μ-Cl)]2. Complexes [Pd(COD)Cl2] and [Pd(C6H5CN)2Cl2] reacted with 1 to give quantitatively the binuclear complex [(COD)Rh(μ-Cl)(μ-Ph2PPy)PdCl2] (10) characterized by IR and NMR spectroscopy. The structure of the dichloromethane solvate of 10 was determined by a X-ray diffraction study. Crystals are triclinic, space group P1, with Z = 2 in a unit cell of dimensions a = 9.282 (5) A?, b = 10.564 (5) A?, c = 14.690 (6) A?, a = 84.35 (3)°, β = 86.32 (3)°, and γ = 79.01 (3)°. The structure has been solved from diffractometer data by Patterson and Fourier methods and refined by full-matrix least squares on the basis of 1443 observed reflections to R and Rw values of 0.0730 and 0.0932, respectively. The binuclear complex consists of the (COD)Rh and PdCl2 moieties held together by Ph2PPy and chloride bridges, with the Pd?Rh separation of 3.210 (4) A?. The compound [Pd(Ph2PPy)Cl2] (11) was isolated by reacting [Pd(COD)Cl2] or [Pd(C6H5CN)2Cl2] with Ph2PPy in the molar ratio 1:1; it is a very reactive species and was found to react with [Rh(COD)(μ-Cl)]2 to give 10. Interestingly, compound 5 was also obtained almost quantitatively, by reacting 10 with CNtBu. In the bimetallic complexes 5 and 10 important bond changes in the Ph2PPy coordination to the rhodium center, with respect to 1, occurred. Reaction sequences for the formation of these compounds were proposed. The presence of unfavorable interactions between the hydrogens of COD ligand and the phenyl groups in the bimetallic intermediates containing the bridging Ph2PPy ligand P bonded to Rh was considered the factor determining the course of reaction.
Arena, Carmela Grazia,Rotondo, Enrico,Faraone, Felice,Lanfranchi, Maurizio,Tiripicchio, Antonio
p. 3877 - 3885
(2008/10/08)

Preparation and properties of inclusion compounds of transition-metal complexes of cycloocta-1,5-diene and norbornadiene with cyclodextrins
Inclusion compounds of rhodium and platinum complexes of cycloocta-1,5-diene (COD) and norbornadiene (NBD) with cyclodextrins were prepared. Two-to-one (cyclodextrin to guest) inclusion compounds were obtained in high yields in a crystalline state by the treatment of β-cyclodextrin (β-CD) with bis(μ-halo)bis(η4-cycloocta-1,5-diene)dirhodium, [Rh(μ-X)(COD)]2 (X = Cl, Br, I), and bis(μ-chloro)bis(η4-norbornadiene)dirhodium, [Rh(μ-Cl)(NBD)]2. The formation of inclusion compounds is selective. One-to-one inclusion compounds were obtained by the reaction of β-CD with (cycloocta-1,5-diene)platinum dihalides, Pt(COD)X2 (X = Cl, Br, I), in high yields, while γ-CD formed 1:1 inclusion compounds with Pt(COD)I2 but not with Pt(COD)Cl2. α-Cyclodextrin did not form inclusion compounds with any transition-metal complexes of cyclooctadiene and norbornadiene. The inclusion compounds are thermally stable and do not liberate the guest when heated to 200°C in vacuo at which temperature the nonincluded guest [Rh(μ-Cl)(COD)]2 already decomposed. The inclusion compounds were characterized by 1H NMR, IR, UV, and circular dichroism spectra. A large induced Cotton effect was observed with β-CD-[Rh(μ-Cl)(COD)]2. The 1H NMR spectrum of [Rh(μ-Cl)(COD)]2 in the presence of β-CD shows two sets of resonances for two different CD species that are assigned to free β-CD and the complexed β-CD, respectively. The binding mode will be discussed.
Harada, Akira,Yamamoto, Shyoko,Takahashi, Shigetoshi
p. 2560 - 2563
(2008/10/08)

Kinetics of the substitution of β-Diketones in β-diketonato(1,5-cyclooctadiene)rhodium(I) complexes by benzoyl-1,1,1-trifluoroacetone
The kinetics and mechanism of the reactions between and trifluorobenzoylacetone (TFBA) to give have been studied in a petroleum-ether medium at various temperatures with UV spectroscopy.The rate law is -d/dt=(ks+ky) and the reaction is shown to proceed via an associative mechanism.The value of ks and ky were determined for various β-diketone complexes with β-diketone=acac, BA, DBM, TFAA and HFAA.The reactivities of the complexes fall as the β-diketone is varied in the sequence BA>acac>DBM>TFAA>HFAA, indicating that electronegative substituents in the β-diketone increase the trans-effect and therefore the strength of the Rh-O bonds.Since the ring opening is the rate-determining step in the reaction.It can be concluded that the complex containing the β-diketone with the largest trans-effect, which gives rise to the strongest Rh-O bonds, will undergo the slowest substitution.The effect of the substituents of the β-diketone (CF3, phenyl and CH3) on the trans-effect is discussed.
Potgieter, J. H.
p. 369 - 376
(2007/10/02)

Ortho-chelated arylrhodium(I) complexes. X-ray structure of RhI[C6H3(CH2NMe2) 2-o,o′-C,N ](COD)
The reaction of Lin[C6H3(CH2NMe 2)-o-R-o′]n with [RhCl(diene)]2 yields the ortho-chelated arylrhodium(I) complexes Rh[C6H3(CH2NMe 2)-o-R-o′](diene) (R = CH2NMe2, diene = COD (1a) or NBD (1b); diene = COD, R = Me (2) or H (3)). The solid-state structure of 1a was determined by a single-crystal X-ray diffraction study. C20H31N2Rh: triclinic, space group P1, with lattice parameters a = 10.169 (1) ?, b = 13.036 (1) ?, c = 14.688 (2) ?, α = 79.54 (1)°, β = 77.04 (1)°, γ = 79.53°; V = 1845.6 (4) ?3, Z = 4; D(calcd) = 1.448 g cm-3. Refinement with 4696 observed reflections converged at R = 0.0395. The structure of 1a consists of a rhodium(I) center that has a square-planar coordination comprising the two double bonds of COD and a C atom and one of the N atoms of the monoanionic aryl ligand. In solution compounds 1 and 2 exhibit dynamic behavior which involves a reversible dissociation of the Rh-N bond and rotation of the aryl moiety around Rh-C. This process, which generates a highly unsaturated T-shaped 14 electron species, is accompanied by the relief of steric repulsions within the complex. Complex 1 reacts with a range of electrophilic reagents leading to Rh-C bond breakage (HX, X = acac, Cl, Br, OAc, OH, OMe, L-alanyl; MXnLm, SnMe2Br2, NiBr2(PBu3)2, ZrCl4, PdCl2(NCPh)2, HgCl2, PtBr2(COD), and [IrCl(COD)]2). A redox reaction of 1 with AgX (X = OAc, NO3) leads to the formation of RhIIIX2[C6H3(CH2NMe 2)2-o,o′](H2O).
Van Der Zeijden, Adolphus A. H.,Van Koten, Gerard,Nordemann, Richard A.,Koji?-Prodi?, Biserka,Spek, Anthony L.
p. 1957 - 1966
(2008/10/08)

Bimetallic reactivity. Synthesis of bimetallic complexes containing a bis(phosphino)pyrazole ligand
The ligand PNNHP has been prepared. It is a planar quadridentate ligand consisting of a central pyrazole unit with symmetrically disposed methylenediphenylphosphine arms, and its geometry provides for two metals to reside within cooperative distance but does not allow for metal-metal bond formation. Two types of planar bimetallic complexes have been isolated and characterized: those with anionic bridging groups (X) of the composition [M2(PNNP)(X)L2] (M = Pd(II), X = Cl, L = Cl; M = Rh(I), X = Cl and PPh2, L = CO; M = Ir(I), X = PPh2, L = CO) and those without bridging atoms of the composition [M2(PNNP)L4]+ (M = Pd(II), 2L = π-allyl; M = Rh(I) and Ir(I), 2L = diene and L = CO) have been identified.
Schenck, Terry G.,Downes,Milne,Mackenzie, Peter B.,Boucher, Heather,Whelan, John,Bosnich
p. 2334 - 2337
(2008/10/08)

Synthesis and reactivity of formamidinato rhodium(I) complexes
The syntheses of [Rh(diol)(formamidine)]2 complexes (diol cycloocta-1,5-diene (1); diol norbornadiene (2); formamidine N,N′-di-p-tolylformamidine) are reported. These complexes are dimeric and contain the bridging formamidino ligand. They react with CO, dppe and PPh3 with displacement of the diene ligand to yield the known [Rh(CO)2(formamidine)]2, [Rh(dppe)2]+ and [Rh(PPh3)2(formamidine)], respectively; the last complex, in which the formamidine acts as a chelating ligand, was isolated only as the O2 adduct. With HCl or HBF4 aqueous 1 and 2 do not form hydrides but instead the formamidino cation [p-tolyl-NHCHNHtolyl-p]+ and the complexes [Rh(diol)X]2 (X Cl, F); a possible scheme for the reaction with HCl is proposed. The [Rh(C8H12)(formamidine)]2 complex reacts with heterocumulenes as CS2, SO2, PhNCS and PhNCO with diene displacement; the only product isolated was [Rh(CS2)2(formamidine], to which a polymeric structure is assigned.
Piraino, Pasquale,Tresoldi, Giuseppe,Faraone, Felice
p. 305 - 312
(2007/10/02)

Ring Opening in a Non-basic Medium of 2-Methyl-6-nitrobenzothiazole and H-D Exchange at the 2-Methyl Promoted by Silver(I)
Silver(I) promotes H-D exchange at the 2-methyl group of 2-methyl-6-nitrobenzothiazole (mnbt) in the presence of CD3OD in dimethyl sulphoxide (dmso).Moreover, the alcohol in dmso causes nucleophilic attack at the c2 of mnbt with subsequent cleavage of the C-S bond and opening of the thiazole ring to afford (2-amino-5-nitrobenzenethiolato-S)silver(I).In a similar reaction, the unsubstituted benzothiazole ring is opened to afford the silver(I) salt of 2-aminobenzenethiol.The role of the electronic structure of silver(I) in the ring-opening reaction is discussed and compared with the behaviour of analogous complexes of iron(II) and rhodium(I) with MeOH.
Aresta, Michele,Ciminale, Francesco
p. 1520 - 1523
(2007/10/02)

THE PREPARATION AND REACTIONS OF BIS(PYRAZOLYL)PHENYLMETHANE COMPLEXES OF RHODIUM(I)
The complexes x (I), (II), (III) and +Cl- (IV) have been prepared via the reactions of the bis-(pyrazolyl)phenylmethane ligands PhCH(H2pz)2 (LL; H2pz = pyrazolyl) and PhCH(Me2pz)2 (MeLL; Me2pz = 3,5-dimethylpyrazolyl) with 2 and 2 (cod = cyclooctadiene).Complex IV reacts with NaBPh4 to form +BPh4- (V).III and IV react with carbon monoxide to give +- (VI).Complexes I and III give neutral solutions in methanol, while II and IV behave as 1:2 and 1:1 electrolytes, respectively.The rhodium(I) centre is typically four-coordinate in I, II, IV-VI, and five-coordinate in III.The ligands LL and MeLL show bidentate chelating behaviour in all of the above complexes, with the exception of II, where LL bridges two different RhI moieties.Reactions with H2, HCl and Ph3P are described.Complex III functions as a homogeneous catalyst, in neutral methanolic solution, for the hydrogenation of olefins, but is ineffective for the hydrogenation of α,β-unsaturated aldehydes and ketones.
Leung, Ping Y.,Peterson, Louis K.
p. 409 - 420
(2007/10/02)