Tris(triphenylphosphine)rhodium carbonyl hydride

Last updated
Tris(triphenylphosphine)rhodium carbonyl hydride
HRh(CO)P3again.png
Identifiers
  • 17185-29-4 Yes check.svgY
3D model (JSmol)
ECHA InfoCard 100.037.467 OOjs UI icon edit-ltr-progressive.svg
EC Number
  • 241-230-3
UNII
  • InChI=1S/3C18H15P.CO.Rh.H/c3*1-4-10-16(11-5-1)19(17-12-6-2-7-13-17)18-14-8-3-9-15-18;1-2;;/h3*1-15H;;;
    Key: AACIZACVKFEETJ-UHFFFAOYSA-N
  • [C-]#[O+].C1=CC=C(C=C1)P(C2=CC=CC=C2)C3=CC=CC=C3.C1=CC=C(C=C1)P(C2=CC=CC=C2)C3=CC=CC=C3.C1=CC=C(C=C1)P(C2=CC=CC=C2)C3=CC=CC=C3.[RhH]
Properties
C55H46OP3Rh
Molar mass 918.78
Appearanceyellow solid
Melting point 172–174 °C (342–345 °F; 445–447 K)sealed capillary
Hazards
GHS pictograms GHS-pictogram-skull.svg GHS-pictogram-exclam.svg
GHS Signal word Danger
H301, H311, H315, H319, H331, H335
P261, P264, P270, P271, P280, P301+P310, P302+P352, P304+P340, P305+P351+P338, P311, P312, P321, P322, P330, P332+P313, P337+P313, P361, P362, P363, P403+P233, P405, P501
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

Carbonyl hydrido tris(triphenylphosphine)rhodium(I) [Carbonyl(hydrido)tris(triphenylphosphane)rhodium(I)] is an organorhodium compound with the formula [RhH(CO)(PPh3)3] (Ph = C6H5). It is a yellow, benzene-soluble solid, which is used industrially for hydroformylation. [1]

Contents

Preparation

[RhH(CO)(PPh3)3] was first prepared by the reduction of [RhCl(CO)(PPh3)2], e.g. with sodium tetrahydroborate, or triethylamine and hydrogen, in ethanol in the presence of excess triphenylphosphine:

[RhCl(CO)(PPh3)2] + NaBH4 + PPh3 → [RhH(CO)(PPh3)3] + NaCl + BH3

It can also be prepared from an aldehyde, rhodium trichloride and triphenylphosphine in basic alcoholic media. [2]

Structure

The complex adopts a trigonal bipyramidal geometry with trans CO and hydrido ligands, resulting in pseudo -C3v symmetry. The Rh-P, Rh-C, and Rh-H distances are 2.32, 1.83, and 1.60 Å, respectively. [3] [4] This complex is one of a small number of stable pentacoordinate rhodium hydrides.

Use in hydroformylation

This precatalyst was uncovered in attempts to use tris(triphenylphosphine)rhodium chloride as a hydroformylation catalyst. It was found that the complex would quickly carbonylate and that the catalytic activity of the resulting material was enhanced by a variety of additives but inhibited by halides. This inhibition did not occur in the presence of base, suggesting that the hydrido-complex represented the catalytic form of the complex. [5]

Mechanistic considerations

[RhH(CO)(PPh3)3] is a catalyst for the selective hydroformylation of 1-olefins to produce aldehydes at low pressures and mild temperatures. The selectivity for n-aldehydes increases in the presence of excess PPh3 and at low CO partial pressures. [1] The first step in the hydroformylation process is the dissociative substitution of an alkene for a PPh3. The migratory insertion of this 18-electron complex can result in either a primary or secondary rhodium alkyl. This step sets the regiochemistry of the product, however it is rapidly reversible. The 16-electron alkyl complex undergoes migratory insertion of a CO to form the coordinately unsaturated acyl. This species once again gives an 18-electron acyl complex. [6] The last step involves β-H elimination via hydrogenolysis which results in the cleavage of the aldehyde product and regeneration of the rhodium catalyst.

Related Research Articles

Hydroformylation, also known as oxo synthesis or oxo process, is an industrial process for the production of aldehydes from alkenes. This chemical reaction entails the net addition of a formyl group (CHO) and a hydrogen atom to a carbon-carbon double bond. This process has undergone continuous growth since its invention: Production capacity reached 6.6×106 tons in 1995. It is important because aldehydes are easily converted into many secondary products. For example, the resulting aldehydes are hydrogenated to alcohols that are converted to detergents. Hydroformylation is also used in speciality chemicals, relevant to the organic synthesis of fragrances and drugs. The development of hydroformylation is one of the premier achievements of 20th-century industrial chemistry.

Wilkinsons catalyst Chemical compound

Wilkinson's catalyst is the common name for chloridotris(triphenylphosphine)rhodium(I), a coordination complex of rhodium with the formula [RhCl(PPh3)3] (Ph = phenyl). It is a red-brown colored solid that is soluble in hydrocarbon solvents such as benzene, and more so in tetrahydrofuran or chlorinated solvents such as dichloromethane. The compound is widely used as a catalyst for hydrogenation of alkenes. It is named after chemist and Nobel laureate Sir Geoffrey Wilkinson, who first popularized its use.

Triphenylphosphine Chemical compound

Triphenylphosphine (IUPAC name: triphenylphosphane) is a common organophosphorus compound with the formula P(C6H5)3 and often abbreviated to PPh3 or Ph3P. It is widely used in the synthesis of organic and organometallic compounds. PPh3 exists as relatively air stable, colorless crystals at room temperature. It dissolves in non-polar organic solvents such as benzene and diethyl ether.

Rhodium(III) chloride Chemical compound

Rhodium(III) chloride refers to inorganic compounds with the formula RhCl3(H2O)n, where n varies from 0 to 3. These are diamagnetic solids featuring octahedral Rh(III) centres. Depending on the value of n, the material is either a dense brown solid or a soluble reddish salt. The soluble trihydrated (n = 3) salt is widely used to prepare compounds used in homogeneous catalysis, notably for the industrial production of acetic acid and hydroformylation.

Tetrakis(triphenylphosphine)platinum(0) Chemical compound

Tetrakis(triphenylphosphine)platinum(0) is the chemical compound with the formula Pt(P(C6H5)3)4, often abbreviated Pt(PPh3)4. The bright yellow compound is used as a precursor to other platinum complexes.

Tetrarhodium dodecacarbonyl Chemical compound

Tetrarhodium dodecacarbonyl is the chemical compound with the formula Rh4(CO)12. This dark-red crystalline solid is the smallest stable binary rhodium carbonyl. It is used as a catalyst in organic synthesis.

Organophosphines are organophosphorus compounds with the formula PRnH3−n, where R is an organic substituent. These compounds can be classified according to the value of n: primary phosphines (n = 1), secondary phosphines (n = 2), tertiary phosphines (n = 3). All adopt pyramidal structures. Organophosphines are generally colorless, lipophilic liquids or solids. The parent of the organophosphines is phosphine (PH3).

Martin Arthur Bennett FRS is an Australian inorganic chemist. He gained recognition for studies on the co-ordination chemistry of tertiary phosphines, olefins, and acetylenes, and the relationship of their behaviour to homogeneous catalysis.

Bite angle

In coordination chemistry the bite angle is the ligand–metal–ligand bond angle of coordination complex containing a bidentate ligand. This geometric parameter is used to classify chelating ligands, including those in organometallic complexes. It is most often discussed in terms of catalysis, as changes in bite angle can affect not just the activity and selectivity of a catalytic reaction but even allow alternative reaction pathways to become accessible.

A migratory insertion is a type of reaction in organometallic chemistry wherein two ligands on a metal complex combine. It is a subset of reactions that very closely resembles the insertion reactions, and both are differentiated by the mechanism that leads to the resulting stereochemistry of the products. However, often the two are used interchangeably because the mechanism is sometimes unknown. Therefore, migratory insertion reactions or insertion reactions, for short, are defined not by the mechanism but by the overall regiochemistry wherein one chemical entity interposes itself into an existing bond of typically a second chemical entity e.g.:

Organoiridium compound

Organoiridium chemistry is the chemistry of organometallic compounds containing an iridium-carbon chemical bond. Organoiridium compounds are relevant to many important processes including olefin hydrogenation and the industrial synthesis of acetic acid. They are also of great academic interest because of the diversity of the reactions and their relevance to the synthesis of fine chemicals.

Organoplatinum chemistry is the chemistry of organometallic compounds containing a carbon to platinum chemical bond, and the study of platinum as a catalyst in organic reactions. Organoplatinum compounds exist in oxidation state 0 to IV, with oxidation state II most abundant. The general order in bond strength is Pt-C (sp) > Pt-O > Pt-N > Pt-C (sp3). Organoplatinum and organopalladium chemistry are similar, but organoplatinum compounds are more stable and therefore less useful as catalysts.

Organorhodium chemistry

Organorhodium chemistry is the chemistry of organometallic compounds containing a rhodium-carbon chemical bond, and the study of rhodium and rhodium compounds as catalysts in organic reactions.

Cobalt tetracarbonyl hydride Chemical compound

Cobalt tetracarbonyl hydride is an organometallic compound with the formula HCo(CO)4. It is a volatile, yellow liquid that forms a colorless vapor and has an intolerable odor. The compound readily decomposes upon melt and in absentia of high CO partial pressures forms Co2(CO)8. Despite operational challenges associated with its handling, the compound has received considerable attention for its ability to function as a catalyst in hydroformylation. In this respect, HCo(CO)4 and related derivatives have received significant academic interest for their ability to mediate a variety of carbonylation (introduction of CO into inorganic compounds) reactions.

Metal-phosphine complex

A metal-phosphine complex is a In coordination complex containing one or more phosphine ligands. Almost always, the phosphine is an organophosphine of the type R3P (R = alkyl, aryl). Metal phosphine complexes are useful in homogeneous catalysis. Prominent examples of metal phosphine complexes include Wilkinson's catalyst (Rh(PPh3)3Cl), Grubbs' catalyst, and tetrakis(triphenylphosphine)palladium(0).

Rhodium carbonyl chloride Chemical compound

Rhodium carbonyl chloride is an organorhodium compound with the formula Rh2Cl2(CO)4. It is a red-brown volatile solid that is soluble in nonpolar organic solvents. It is a precursor to other rhodium carbonyl complexes, some of which are useful in homogeneous catalysis.

The Tsuji–Wilkinson decarbonylation reaction is a method for the decarbonylation of aldehydes and some acyl chlorides. The reaction name recognizes Jirō Tsuji, whose team first reported the use of Wilkinson's catalyst (RhCl(PPh3)3) for these reactions:

Hydridotetrakis(triphenylphosphine)rhodium(I) Chemical compound

Hydridotetrakis(triphenylphosphine)rhodium(I) is the coordination complex with the formula HRh[P(C6H5)3]4. It consists of a Rh(I) center complexed to four triphenylphosphine (PPh3) ligands and one hydride. The molecule has idealized C3v symmetry. The compound is a homogeneous catalyst for hydrogenation and related reactions. It is a yellow solid that dissolves in aromatic solvents.

Bis(triphenylphosphine)rhodium carbonyl chloride Chemical compound

Bis(triphenylphosphine)rhodium carbonyl chloride is the organorhodium complex with the formula [RhCl(CO)(PPh3)2]. This complex of rhodium(I) is a bright yellow, air-stable solid. It is the Rh analogue of Vaska's complex, the corresponding iridium complex. With regards to its structure, the complex is square planar with mutually trans triphenylphosphine (PPh3) ligands. The complex is a versatile homogeneous catalyst.

Transition metal acyl complexes

Transition metal acyl complexes describes organometallic complexes containing one or more acyl (RCO) ligands. Such compounds occur as transient intermediates in many industrially useful reactions, especially carbonylations.

References

  1. 1 2 J. F. Hartwig; Organotransition metal chemistry - from bonding to catalysis. University Science Books. 2009. 753, 757-578. ISBN   978-1-891-38953-5.
  2. Ahmad, N.; Levison, J. J.; Robinson, S. D.; Uttley, M. F. (1990). "Hydrido Phosphine Complexes of Rhodium(I)". Inorganic Syntheses. Inorganic Syntheses. 28. pp. 81–83. doi:10.1002/9780470132593.ch19. ISBN   9780470132593.
  3. I. S. Babra, L. S. Morley, S. C. Nyburg, A. W. Parkins "The crystal and molecular structure of a new polymorph of a carbonlyhydridotris(triphenylphosphine)rhodium(I) having a Rh-H stretching absorption at 2013 cm−1" Journal of Crystallographic and Spectroscopic Research 23. 1993. 999. doi : 10.1007/BF01185550.
  4. S. J. la Placa, J. A. Ibers "Crystal and Molecular Structure of Tristriphenylphosphine Rhodium Carbonyl Hydride" Acta Crystallogr. 1965, p. 511. doi : 10.1107/S0365110X65001093
  5. D. Evans, J. A. Osborn, G. Wilkinson "Hydroformylation of Alkenes by Use of Rhodium Complex Catalysts" J. Chem. Soc. 1968, pp. 3133-3142. doi : 10.1039/J19680003133
  6. R. V. Kastrup, J. S. Merola, A. A. Oswald; P-31 NMR Studies of Equilibria and Ligand Exchange in Triphenylphosphine Rhodium Complex and Related Chelated Bisphosphine Rhodium Complex Hydroformylation Catalyst Systems. J. Am. Chem. Soc. 1982.44-16. doi : 10.1021/ba-1982-0196.ch003.