Organoruthenium chemistry

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Organoruthenium chemistry is the chemistry of organometallic compounds containing a carbon to ruthenium chemical bond. Several organoruthenium catalysts are of commercial interest [1] and organoruthenium compounds have been considered for cancer therapy. [2] The chemistry has some stoichiometric similarities with organoiron chemistry, as iron is directly above ruthenium in group 8 of the periodic table. The most important reagents for the introduction of ruthenium are ruthenium(III) chloride and triruthenium dodecacarbonyl.

Contents

In its organometallic compounds, ruthenium is known to adopt oxidation states from -2 ([Ru(CO)4]2−) to +6 ([RuN(Me)4]−). Most common are those in the 2+ oxidation state, as illustrated below.

Ligands

As with other late transition metals, ruthenium binds more favorably with soft ligands. [3] The most important ligands for ruthenium are:

Phosphine ligands

While monodentate phosphine ligands such as triphenylphosphine and tricyclohexylphosphine are most common, bidentate phosphine ligands can also be useful in organoruthenium compounds. BINAP, in particular, is a useful asymmetric ligand for many asymmetric ruthenium catalysts. [4] [5] [6] [7]

N-Heterocyclic carbene ligands

NHC ligands have become very common in organoruthenium complexes. [8] [9] NHC ligands can be prepared with precise steric and electronic parameters, and can be chiral for use in asymmetric catalysis. [10] NHCs, as strongly donating L-type ligands, are often used to replace phosphine ligands. A notable example is 2nd generation Grubbs catalyst, in which a phosphine of the 1st generation catalyst is replaced by an NHC.

Cyclopentadienyl ligands

The parent compound ruthenocene is unreactive because it is coordinatively saturated and contains no reactive groups. Shvo catalyst ([Ph4(η5-C4CO)]2H]}Ru2(CO)4(μ-H)) is also coordinatively saturated, but features reactive OH and RuH groups that enable it to function in transfer hydrogenation. [11] It is used in hydrogenation of aldehydes, ketones, via transfer hydrogenation, in disproportionation of aldehydes to esters and in the isomerization of allylic alcohols.

Chloro(cyclopentadienyl)bis(triphenylphosphine)ruthenium features a reactive chloro group, which is readily substituted by organic substrates.

Arene and alkene ligands

One example of an Ru-arene complex is (cymene)ruthenium dichloride dimer, which is the precursor to a versatile catalyst for transfer hydrogenation. [12] Acenaphthylene forms a useful catalyst derived from triruthenium dodecacarbonyl. [13] The hapticity of the hexamethylbenzene ligand in Ru(C6Me6)2 depends on the oxidation state of the metal centre: [14] The compound Ru(COD)(COT) is capable of dimerizing norbornadiene:

Norbornadiene dimerization Norbornadiene dimerization.svg
Norbornadiene dimerization

Multinuclear organo-ruthenium complexes have been investigated for anti-cancer properties. The compounds studied include di-, tri-, and tetra-nuclear complexes and tetrara-, hexa-, and octa- metalla-cages. [2]

Carbonyls

The main ruthenium carbonyl is triruthenium dodecacarbonyl, Ru3(CO)12. The analogues of the popular reagents Fe(CO)5 and Fe2(CO)9 are not very useful. Ruthenium pentacarbonyl decarbonylates readily:

Ru3(CO)12 + 3 CO 3 Ru(CO)5

Carbonylation of ruthenium trichloride gives a series of Ru(II) chlorocarbonyls. These are the precursors to Ru3(CO)12.

Organoosmium compounds

In the same group 8 elements osmium resembles ruthenium in its complexes. [15] Because Os is more expensive than Ru, the chemistry is less developed and has fewer applications. Of course the cost of the catalyst is offset if turnover numbers are high. [16] Thus, osmium tetroxide is an important oxidizing agent in organic chemistry especially in the conversion of alkenes to 1,2-diols. [17]

The 5d-orbitals in Os are higher in energy that the 4d-orbitals in Ru. Thus, π backbonding to alkenes and CO is stronger for Os compounds, which leads to more stable organic derivatives. This effect is illustrated by the stability of the alkene derivatives of the type [Os(NH3)5(alkene)]2+ or [Os(NH3)5(arene)]2+ [18] as in the example below.

OsA5(eta-2-benzene).png

Important compounds, at least for academic studies, are the carbonyls such as triosmium dodecacarbonyl and decacarbonyldihydridotriosmium. The phosphine complexes are analogous to those or ruthenium, but hydride derivatives, e.g. OsHCl(CO)(PPh3)3, tend to be more stable. [19]

Related Research Articles

Grubbs catalysts are a series of transition metal carbene complexes used as catalysts for olefin metathesis. They are named after Robert H. Grubbs, the chemist who supervised their synthesis. Several generations of the catalyst have also been developed. Grubbs catalysts tolerate many functional groups in the alkene substrates, are air-tolerant, and are compatible with a wide range of solvents. For these reasons, Grubbs catalysts have become popular in synthetic organic chemistry. Grubbs, together with Richard R. Schrock and Yves Chauvin, won the Nobel Prize in Chemistry in recognition of their contributions to the development of olefin metathesis.

A transition metal carbene complex is an organometallic compound featuring a divalent carbon ligand, itself also called a carbene. Carbene complexes have been synthesized from most transition metals and f-block metals, using many different synthetic routes such as nucleophilic addition and alpha-hydrogen abstraction. The term carbene ligand is a formalism since many are not directly derived from carbenes and most are much less reactive than lone carbenes. Described often as =CR2, carbene ligands are intermediate between alkyls (−CR3) and carbynes (≡CR). Many different carbene-based reagents such as Tebbe's reagent are used in synthesis. They also feature in catalytic reactions, especially alkene metathesis, and are of value in both industrial heterogeneous and in homogeneous catalysis for laboratory- and industrial-scale preparation of fine chemicals.

<span class="mw-page-title-main">Ruthenium(III) chloride</span> Chemical compound

Ruthenium(III) chloride is the chemical compound with the formula RuCl3. "Ruthenium(III) chloride" more commonly refers to the hydrate RuCl3·xH2O. Both the anhydrous and hydrated species are dark brown or black solids. The hydrate, with a varying proportion of water of crystallization, often approximating to a trihydrate, is a commonly used starting material in ruthenium chemistry.

<span class="mw-page-title-main">Triruthenium dodecacarbonyl</span> Chemical compound

Triruthenium dodecacarbonyl is the chemical compound with the formula Ru3(CO)12. Classified as metal carbonyl cluster, it is a dark orange-colored solid that is soluble in nonpolar organic solvents. The compound serves as a precursor to other organoruthenium compounds.

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.

<span class="mw-page-title-main">Metallacycle</span>

In organometallic chemistry, a metallacycle is a derivative of a carbocyclic compound wherein a metal has replaced at least one carbon center; this is to some extent similar to heterocycles. Metallacycles appear frequently as reactive intermediates in catalysis, e.g. olefin metathesis and alkyne trimerization. In organic synthesis, directed ortho metalation is widely used for the functionalization of arene rings via C-H activation. One main effect that metallic atom substitution on a cyclic carbon compound is distorting the geometry due to the large size of typical metals.

<span class="mw-page-title-main">Organoiridium chemistry</span> Chemistry of organometallic compounds containing an iridium-carbon bond

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.

Organoiron chemistry is the chemistry of iron compounds containing a carbon-to-iron chemical bond. Organoiron compounds are relevant in organic synthesis as reagents such as iron pentacarbonyl, diiron nonacarbonyl and disodium tetracarbonylferrate. Although iron is generally less active in many catalytic applications, it is less expensive and "greener" than other metals. Organoiron compounds feature a wide range of ligands that support the Fe-C bond; as with other organometals, these supporting ligands prominently include phosphines, carbon monoxide, and cyclopentadienyl, but hard ligands such as amines are employed as well.

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.

<span class="mw-page-title-main">Shvo catalyst</span> Chemical compound

The Shvo catalyst is an organoruthenium compound that catalyzes the hydrogenation of polar functional groups including aldehydes, ketones and imines. The compound is of academic interest as an early example of a catalyst for transfer hydrogenation that operates by an "outer sphere mechanism". Related derivatives are known where p-tolyl replaces some of the phenyl groups. Shvo's catalyst represents a subset of homogeneous hydrogenation catalysts that involves both metal and ligand in its mechanism.

<span class="mw-page-title-main">Dichlorotris(triphenylphosphine)ruthenium(II)</span> Chemical compound

Dichlorotris(triphenylphosphine)ruthenium(II) is a coordination complex of ruthenium. It is a chocolate brown solid that is soluble in organic solvents such as benzene. The compound is used as a precursor to other complexes including those used in homogeneous catalysis.

<span class="mw-page-title-main">Tolman electronic parameter</span>

The Tolman electronic parameter (TEP) is a measure of the electron donating or withdrawing ability of a ligand. It is determined by measuring the frequency of the A1 C-O vibrational mode (ν(CO)) of a (pseudo)-C3v symmetric complex, [LNi(CO)3] by infrared spectroscopy, where L is the ligand of interest. [LNi(CO)3] was chosen as the model compound because such complexes are readily prepared from tetracarbonylnickel(0). The shift in ν(CO) is used to infer the electronic properties of a ligand, which can aid in understanding its behavior in other complexes. The analysis was introduced by Chadwick A. Tolman.

A metal carbido complex is a coordination complex that contains a carbon atom as a ligand. They are analogous to metal nitrido complexes. Carbido complexes are a molecular subclass of carbides, which are prevalent in organometallic and inorganic chemistry. Carbido complexes represent models for intermediates in Fischer–Tropsch synthesis, olefin metathesis, and related catalytic industrial processes. Ruthenium-based carbido complexes are by far the most synthesized and characterized to date. Although, complexes containing chromium, gold, iron, nickel, molybdenum, osmium, rhenium, and tungsten cores are also known. Mixed-metal carbides are also known.

<span class="mw-page-title-main">Half sandwich compound</span> Class of coordination compounds

Half sandwich compounds, also known as piano stool complexes, are organometallic complexes that feature a cyclic polyhapto ligand bound to an MLn center, where L is a unidentate ligand. Thousands of such complexes are known. Well-known examples include cyclobutadieneiron tricarbonyl and (C5H5)TiCl3. Commercially useful examples include (C5H5)Co(CO)2, which is used in the synthesis of substituted pyridines, and methylcyclopentadienyl manganese tricarbonyl, an antiknock agent in petrol.

A metal-centered cycloaddition is a subtype of the more general class of cycloaddition reactions. In such reactions "two or more unsaturated molecules unite directly to form a ring", incorporating a metal bonded to one or more of the molecules. Cycloadditions involving metal centers are a staple of organic and organometallic chemistry, and are involved in many industrially-valuable synthetic processes.

<span class="mw-page-title-main">Palladium–NHC complex</span>

In organometallic chemistry, palladium-NHC complexes are a family of organopalladium compounds in which palladium forms a coordination complex with N-heterocyclic carbenes (NHCs). They have been investigated for applications in homogeneous catalysis, particularly cross-coupling reactions.

Metal arene complexes are organometallic compounds of the formula (C6R6)xMLy. Common classes are of the type (C6R6)ML3 and (C6R6)2M. These compounds are reagents in inorganic and organic synthesis. The principles that describe arene complexes extend to related organic ligands such as many heterocycles (e.g. thiophene) and polycyclic aromatic compounds (e.g. naphthalene).

A transition metal phosphido complex is a coordination complex containing a phosphido ligand (R2P, where R = H, organic substituent). With two lone pairs on phosphorus, the phosphido anion (R2P−) is comparable to an amido anion (R2N−), except that the M-P distances are longer and the phosphorus atom is more sterically accessible. For these reasons, phosphido is often a bridging ligand. The -PH2 ion or ligand is also called phosphanide or phosphido ligand.

<span class="mw-page-title-main">Dichlororuthenium tricarbonyl dimer</span> Chemical compound

Dichlororuthenium tricarbonyl dimer is an organoruthenium compound with the formula [RuCl2(CO)3]2. A yellow solid, the molecule features a pair of octahedral Ru centers bridged by a pair of chloride ligands. The complex is a common starting material in ruthenium chemistry.

<span class="mw-page-title-main">Tris(cyclooctatetraene)triiron</span> Chemical compound

Tris(cyclooctatetraene)triiron or Fe3(COT)3, also referred to as the Lavallo-Grubbs compound (after its discoverers) is an organoiron compound with the formula Fe3(C8H8)3. It is a pyrophoric, black crystalline solid, which is insoluble in common organic solvents.The compound represents a rare example of a hydrocarbon analogue of the well-known Triiron dodecacarbonyl (Fe3(CO)12), originally prepared by Dewar and Jones in the early 20th century.

References

  1. ↑ Synthesis of Organometallic Compounds: A Practical Guide Sanshiro Komiya Ed. S. Komiya, M. Hurano 1997
  2. 1 2 Babak, Maria V.; Wee, Han Ang (2018). "Chapter 6. Multinuclear Organometallic Ruthenium-Arene Complexes for Cancer Therapy". In Sigel, Astrid; Sigel, Helmut; Freisinger, Eva; Sigel, Roland K. O. (eds.). Metallo-Drugs:Development and Action of Anticancer Agents. Metal Ions in Life Sciences. Vol. 18. Berlin: de Gruyter GmbH. pp. 171–198. doi:10.1515/9783110470734-012. PMID   29394025.
  3. ↑ Barthazy, P.; Stoop, R. M.; Wörle, M.; Togni, A.; Mezzetti, A. (2000). "Toward Metal-Mediated C-F Bond Formation. Synthesis and Reactivity of the 16-Electron Fluoro Complex [RuF(dppp)2]PF6 (dppp = 1,3-Bis(diphenylphosphino)propane)". Organometallics. 19: 2844–2852. doi:10.1021/om0000156.
  4. ↑ Example: Organic Syntheses, Coll. Vol. 10, p.276 (2004); Vol. 77, p.1 (2000). Link
  5. ↑ Example: Organic Syntheses, Organic Syntheses, Coll. Vol. 9, p.589 (1998); Vol. 71, p.1 (1993). Link
  6. ↑ Example: Organic Syntheses, Coll. Vol. 9, p.169 (1998); Vol. 72, p.74 (1995). Link
  7. ↑ Example: Organic Syntheses, Vol. 81, p.178 (2005). Link
  8. ↑ Öfele, K.; Tosh, E.; Taubmann, C.; Herrmann, W.A. (2009). "Carbocyclic Carbene Metal Complexes". Chemical Reviews. 109 (8): 3408–3444. doi:10.1021/cr800516g. PMID   19449832.
  9. ↑ Samojłowicz, C.; Bieniek, M.; Grela, K. (2009). "Ruthenium-Based Olefin Metathesis Catalysts Bearing N-Heterocyclic Carbene Ligands". Chemical Reviews. 109 (8): 3708–3742. doi:10.1021/cr800524f. PMID   19534492.
  10. ↑ Benhamou, L.; Chardon, E.; Lavigne, G.; Bellemin-Laponnaz, S.; César, V. (2011). "Synthetic Routes to N-Heterocyclic Carbene Precursors" (PDF). Chemical Reviews. 111 (12): 2705–2733. doi:10.1021/cr100328e. PMID   21235210.
  11. ↑ Conley, B.; Pennington-Boggio, M.; Boz, E.; Williams, T. (2010). "Discovery, Applications, and Catalytic Mechanisms of Shvo's Catalyst". Chemical Reviews. 110 (4): 2294–2312. doi:10.1021/cr9003133. PMID   20095576.
  12. ↑ Organic Syntheses, Organic Syntheses, Vol. 82, p.10 (2005).Link
  13. ↑ Example: Organic Syntheses, Organic Syntheses, Vol. 82, p.188 (2005). Link
  14. ↑ Huttner, Gottfried; Lange, Siegfried; Fischer, Ernst O. (1971). "Molecular Structure of Bis(Hexamethylbenzene)-Ruthenium(0)". Angewandte Chemie International Edition in English . 10 (8): 556–557. doi:10.1002/anie.197105561.
  15. ↑ Cerón-Camacho, Ricardo; Roque-Ramires, Manuel A.; Ryabov, Alexander D.; Le Lagadec, Ronan (2021-03-12). "Cyclometalated Osmium Compounds and beyond: Synthesis, Properties, Applications". Molecules. 26 (6): 1563. doi: 10.3390/molecules26061563 . ISSN   1420-3049. PMC   7999153 . PMID   33809231.
  16. ↑ Ogba, O. M.; Warner, N. C.; O’Leary, D. J.; Grubbs, R. H. (2018). "Recent advances in ruthenium-based olefin metathesis". Chemical Society Reviews. 47 (12): 4510–4544. doi:10.1039/C8CS00027A. ISSN   0306-0012. PMC   6107346 . PMID   29714397.
  17. ↑ Ouellette, Robert J.; Rawn, J. David (2019). "6 - Alkenes: Addition Reactions". Organic Chemistry (2nd ed.). Academic Press. pp. 167–193. doi:10.1016/C2016-0-04004-4. ISBN   978-0-12-812838-1.
  18. ↑ Gilbert, Thomas M. (2023-05-29). "π Acceptor Abilities of Anionic Ligands: Comparisons Involving Anionic Ligands Incorporated into Linear d 10 [(NH 3 )Pd(A)] − , Square Planar d 8 [(NN 2 )Ru(A)] − , and Octahedral d 6 [(AsN 4 )Tc(A)] − Complexes". Inorganic Chemistry. 62 (21): 8069–8079. doi:10.1021/acs.inorgchem.2c03778. ISSN   0020-1669. PMID   37195088.
  19. ↑ Perry, Paxtan (2022). "The Synthesis and Analysis of Triosmium Carbonyl Clusters with Potential Biological Activity" (PDF). Drew University . Retrieved 2024-05-08.
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