Methylidynetricobaltnonacarbonyl

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Methylidynetricobalt­nonacarbonyl
HCCo3(CO)9.png
HCCo3sample.jpg
Names
Other names
methylidyne-tris(tricarbonylcobalt)
Identifiers
3D model (JSmol)
PubChem CID
  • InChI=1S/9CO.CH.3Co/c9*1-2;;;;/h;;;;;;;;;1H;;;/q9*+1;;3*-3
    Key: WPOHNFRRRVAWSE-UHFFFAOYSA-N
  • [O+]#C[Co-3]12(C#[O+])(C#[O+])[Co-3]3(C#[O+])(C#[O+])(C#[O+])[Co-3]1(C#[O+])(C#[O+])(C#[O+])C23
Properties
C10HCo3O9
Molar mass 441.909 g·mol−1
Appearancepurple solid
Density 2.01 g/cm3
Melting point 105–107 °C (221–225 °F; 378–380 K)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

Methylidynetricobaltnonacarbonyl is an organometallic cobalt cluster with the chemical formula Co3(CO)9CH that contains a metal carbonyl core with the methylidyne ligand, first discovered in the late 1950s. A variety of substituents can be added to the methylidyne group to form derivatives of the parent compound that have unique spectroscopic properties and reactivity. This page will explore the discovery and synthesis of methylidynetricobaltnonacarbonyl, the structure and bonding of the parent compound, as well as some examples reactivity and catalysis with the cluster.

Contents

Synthesis

Methylidynetricobaltnonacarbonyl and derivatives were discovered in the late 1950s by Markby and Wender by reactions of the alkyne complexes Co2(CO)6(R2C2) with acids. The structure of the cluster was however misformulated. [1] In 1962, the class of compounds were properly formulated methylidynetricobaltnonacarbonyl as well as several derivatives. [2]

The synthetic procedure developed by Bor and coworkers relied on the reaction of [Co(CO)4]- anion with chloroform, bromoform, or iodoform in a solution of acetone or THF. Dark violet crystals were obtained in ~20% yield with chloroform, ~18% yield with bromoform, and ~1-2% yield with iodoform. The chloride derivative Co3(CO)9CCl was obtained with CCl4 and was isolated as shiny, lilac crystals. Several other functional groups could be installed, including C6H5 and CO2CH3, all of which afforded dark violet crystals. Solutions of these compounds are air stable in organic solvents. Treatment of the parent compound with 100 atm CO at 160 °C resulted in the destruction of the complex and the formation of dicobaltoctacarbonyl. [2]

3NaCo(CO)4 + CHCl3 → HC[Co(CO)3]3 + 3 NaCl

Structure and Bonding

The Co-Co bond lengths are ~2.47 Å and the Co-C bond distances are ~1.88 Å. [2] [3] These bond lengths do not change significantly depending on the substituent on the carbon group. The Co-C-Co angle is approximately 80°, indicating a significant bending of the carbon tetrahedral structure, and the ligands are arranged to provide maximum cobalt-carbon interaction. [4] The IR spectra show four absorption bands of varying intensities in the region of terminal C-O groups between 2111 and 2018 cm-1. The 13C NMR spectra have also been analyzed. [5] The mass spectra demonstrate parent molecular ions (Co3(CO)9CH .+) in good abundance, which demonstrates the high stability of the Co3(CO)9 clusters towards oxidation. Initial loss of CO, which is characteristic of most metal-carbonyls, though rupture of the metal-metal bond also often occurs. [4]

Series of mixed organic and inorganic tetrahedrane structures illustrating that Co(CO)3 and methylidyne are isolobal. ClusterScheme.png
Series of mixed organic and inorganic tetrahedrane structures illustrating that Co(CO)3 and methylidyne are isolobal.

The carbonium ion had the correct symmetry to accept electron density from the apex carbon via s-p stabilization. They explained that apex carbon stabilize the carbonium ion via s-p conjugation. [7]

Visual representation of methylidynetricobaltnonacarbonyl isolobal analogy with the CH fragment Methylidynetricobaltnonacarbonyl isolobal analogy.png
Visual representation of methylidynetricobaltnonacarbonyl isolobal analogy with the CH fragment

Reactivity

14CO labelling studies on the kinetics have been reported. [8] The group concluded the exchange rate of the carbonyl ligands decreases according to the order F > Cl > Br > H, which they attributed to the electronegativity of the atom bound to the methylidyne carbon. Additionally, they demonstrated that the nine carbonyl groups are not kinetically equivalent, and that only 3 CO groups exchange within the 35–55 °C temperature range studied, which agrees with the calculated frontier molecular orbitals discussed above. In the case with the COOCH3 group, the exchange occurs for only one CO group which they attributed to the more electron deficient nature of the complex. [8]

Methylidynetricobaltnonacarbonyls reacts with variety of organomercury compounds of the R2Hg and RHgX type; the side product Hg[Co(CO)4]2 was formed. [9]

Azobisisobutryonitrile (AIBN), a reagent for the initiation of radical reactions, to a solution of Co3(CO)9CH and allyl acetate afforded a red crystalline solid that they believed formed via a radical mechanism. [10] The radical reactivity of Co3(CO)9CX varies with X. The order of initiator activity was found to be X = Cl > H > Br > Ph > F > i-Pr > C2F5, which aligns with the trend seen for CO ligand exchange studies. [11] [12] These cobalt carbonyl clusters undergo reversible, one-electron reduction in the range of -0.7 to -0.9V versus the saturated calomel electrode. [13]

Methylidynetricobaltnonacarbonyl catalyzes the Pauson-Khand reaction, a [2+2+1] cycloaddition. [14] Methylidynetricobaltnonacarbonyl is more air-stable than the parent dicobalt octacarbonyl, making it a more attractive catalyst. The clusters demonstrated no need for additives such as trimethylphosphite, as is necessary with the dicobalt octacarbonyl, and the best results were obtained with the parent methylidyne cluster. [14]

Pauson-Khand reaction using methlylidynetricobaltnonacarbonyl as a catalyst PausonKhand.png
Pauson-Khand reaction using methlylidynetricobaltnonacarbonyl as a catalyst

Methylidynetricobaltnonacarbonyl derivatives are precatalysts for the asymmetric intramolecular Pauson-Khand reaction. The chiral diphosphine Josiphos provides the asymmetry. Despite the unique approach, the clusters are inferior compared to other metal clusters with NORPHOS or Me-DuPHOS ligands, which gave higher yields and fewer side products. [15]

Related Research Articles

<span class="mw-page-title-main">Pauson–Khand reaction</span> Chemical reaction

The Pauson–Khand (PK) reaction is a chemical reaction, described as a [2+2+1] cycloaddition. In it, an alkyne, an alkene, and carbon monoxide combine into a α,β-cyclopentenone in the presence of a metal-carbonyl catalyst Ihsan Ullah Khand (1935–1980) discovered the reaction around 1970, while working as a postdoctoral associate with Peter Ludwig Pauson (1925–2013) at the University of Strathclyde in Glasgow. Pauson and Khand's initial findings were intermolecular in nature, but the reaction has poor selectivity. Some modern applications instead apply the reaction for intramolecular ends.

<span class="mw-page-title-main">Molybdenum hexacarbonyl</span> Chemical compound

Molybdenum hexacarbonyl (also called molybdenum carbonyl) is the chemical compound with the formula Mo(CO)6. This colorless solid, like its chromium, tungsten, and seaborgium analogues, is noteworthy as a volatile, air-stable derivative of a metal in its zero oxidation state.

<span class="mw-page-title-main">Dicobalt octacarbonyl</span> Chemical compound

Dicobalt octacarbonyl is an organocobalt compound with composition Co2(CO)8. This metal carbonyl is used as a reagent and catalyst in organometallic chemistry and organic synthesis, and is central to much known organocobalt chemistry. It is the parent member of a family of hydroformylation catalysts. Each molecule consists of two cobalt atoms bound to eight carbon monoxide ligands, although multiple structural isomers are known. Some of the carbonyl ligands are labile.

<span class="mw-page-title-main">Methylidyne radical</span> Chemical compound

Methylidyne, or (unsubstituted) carbyne, is an organic compound whose molecule consists of a single hydrogen atom bonded to a carbon atom. It is the parent compound of the carbynes, which can be seen as obtained from it by substitution of other functional groups for the hydrogen.

The Nicholas reaction is an organic reaction where a dicobalt octacarbonyl-stabilized propargylic cation is reacted with a nucleophile. Oxidative demetallation gives the desired alkylated alkyne. It is named after Kenneth M. Nicholas.

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

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

<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.

<span class="mw-page-title-main">Organocobalt chemistry</span> Chemistry of compounds with a carbon to cobalt bond

Organocobalt chemistry is the chemistry of organometallic compounds containing a carbon to cobalt chemical bond. Organocobalt compounds are involved in several organic reactions and the important biomolecule vitamin B12 has a cobalt-carbon bond. Many organocobalt compounds exhibit useful catalytic properties, the preeminent example being dicobalt octacarbonyl.

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.

<span class="mw-page-title-main">Organosilver chemistry</span> Study of chemical compounds containing carbon-silver chemical bonds

Organosilver chemistry is the study of organometallic compounds containing a carbon to silver chemical bond. The theme is less developed than organocopper chemistry.

<span class="mw-page-title-main">Iron tetracarbonyl dihydride</span> Chemical compound

Iron tetracarbonyl dihydride is the organometallic compound with the formula H2Fe(CO)4. This compound was the first transition metal hydride discovered. The complex is stable at low temperatures but decomposes rapidly at temperatures above –20 °C.

<span class="mw-page-title-main">Rhodocene</span> Organometallic chemical compound

Rhodocene is a chemical compound with the formula [Rh(C5H5)2]. Each molecule contains an atom of rhodium bound between two planar aromatic systems of five carbon atoms known as cyclopentadienyl rings in a sandwich arrangement. It is an organometallic compound as it has (haptic) covalent rhodium–carbon bonds. The [Rh(C5H5)2] radical is found above 150 °C (302 °F) or when trapped by cooling to liquid nitrogen temperatures (−196 °C [−321 °F]). At room temperature, pairs of these radicals join via their cyclopentadienyl rings to form a dimer, a yellow solid.

Transition metal carbyne complexes are organometallic compounds with a triple bond between carbon and the transition metal. This triple bond consists of a σ-bond and two π-bonds. The HOMO of the carbyne ligand interacts with the LUMO of the metal to create the σ-bond. The two π-bonds are formed when the two HOMO orbitals of the metal back-donate to the LUMO of the carbyne. They are also called metal alkylidynes—the carbon is a carbyne ligand. Such compounds are useful in organic synthesis of alkynes and nitriles. They have been the focus on much fundamental research.

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">Tetracobalt dodecacarbonyl</span> Chemical compound

Tetracobalt dodecacarbonyl is the chemical compound with the formula Co4(CO)12. It is a black crystalline compound that is insoluble in water and easily oxidized by air. It is an example of a metal carbonyl cluster.

In organometallic chemistry, a transition metal alkyne complex is a coordination compound containing one or more alkyne ligands. Such compounds are intermediates in many catalytic reactions that convert alkynes to other organic products, e.g. hydrogenation and trimerization.

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).

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

In chemistry, a metallaborane is a compound that contains one or more metal atoms and one or more boron hydride. These compounds are related conceptually and often synthetically to the boron-hydride clusters by replacement of BHn units with metal-containing fragments. Often these metal fragments are derived from metal carbonyls or cyclopentadienyl complexes. Their structures can often be rationalized by polyhedral skeletal electron pair theory. The inventory of these compounds is large, and their structures can be quite complex.

The stabilization of bismuth's +3 oxidation state due to the inert pair effect yields a plethora of organometallic bismuth-transition metal compounds and clusters with interesting electronics and 3D structures.

<span class="mw-page-title-main">Disulfidobis(tricarbonyliron)</span> Chemical compound

Disulfidobis(tricarbonyliron), or Fe2(μ-S2)(CO)6, is an organometallic molecule used as a precursor in the synthesis of iron-sulfur compounds. Popularized as a synthetic building block by Dietmar Seyferth, Fe2(μ-S2)(CO)6 is commonly used to make mimics of the H-cluster in [FeFe]-hydrogenase. Much of the reactivity of Fe2(μ-S2)(CO)6 proceeds through its sulfur-centered dianion, [Fe2(μ-S)2(CO)2]2-.

References

  1. ↑ Markby, Raymond; Wender, Irving; Friedel, R. A.; Cotton, F. A.; Sternberg, Heinz W. (1958). "The Association of an Acetylene with Three Metal Atoms; A New Trinuclear Cobalt Complex". Journal of the American Chemical Society. 80 (24): 6529–6533. doi:10.1021/ja01557a018.
  2. 1 2 3 Bor, György; Markó, László; Markó, Bernadett (1962). "Kobaltcarbonylderivate des Tetrachlorkohlenstoffs und organischer 1.1.1-Trihalogenverbindungen: Trikobalt-enneacarbonyl-kohlenstoff-Verbindungen". Chemische Berichte. 95 (2): 333–340. doi:10.1002/cber.19620950207.
  3. ↑ Castellani, Michael P.; Smith, William G.; Patel, Nimish G.; Bott, Simon G.; Richmond, Michael G. (1999). "Reaction of ethyl diazoacetate with Co3(CO)9(μ3-CCL): Isolation and X-ray structures of Co3(CO)9(μ3-CCO2Et), Co3(CO)9(μ3-CCH2CO2Et), and [Co3(CO)9(μ3-CCHCO2Et)]2". Journal of Chemical Crystallography. 29 (5): 609–617. doi:10.1023/A:1009561205829.
  4. 1 2 Robinson, B. H.; Tham, W. S. (1968). "Chemistry of methinyltricobalt enneacarbonyls. Part I. Mass spectra". Journal of the Chemical Society A: Inorganic, Physical, Theoretical: 1784. doi:10.1039/J19680001784..
  5. ↑ Aime, S.; Milone, L.; Valle, M. (1976). "13C NMR study of methynyltricobalt enneacarbonyls". Inorganica Chimica Acta. 18: 9–11. doi:10.1016/S0020-1693(00)95577-4.
  6. ↑ Schilling, Birgitte E. R.; Hoffmann, Roald (1979). "M3L9(ligand) complexes". Journal of the American Chemical Society. 101 (13): 3456–3467. doi:10.1021/ja00507a006.
  7. ↑ Seyferth, D.; Williams, G. H.; Hallgren, J. E. J. Am. Chem. Soc. 1973, 95 (1), 266-267. DOI: 10.1021/ja00782a060.
  8. 1 2 Cetini, N.; Ercoli, R.; Gambino, O.; Vaglio, G. Atti della Accademia delle Scienze di Torino, Clase di Scienze Fisiche, Matematiche e Naturali 1965, 99, 1123-1126.
  9. ↑ Seyferth, Dietmar; Hallgren, John E.; Spohn, Ralph J. (1970). "The C-arylation and alkylation of methylidynetricobalt nonacarbonyls by organomercury compounds". Journal of Organometallic Chemistry. 23 (2): C55–C57. doi:10.1016/S0022-328X(00)92937-1.
  10. ↑ Seyferth, Dietmar; Hallgren, John E. (1973). "Organocobalt cluster complexes X. Evidence for the methylidynetricobalt nonacarbonyl radical". Journal of Organometallic Chemistry. 49: C41–C42. doi:10.1016/S0022-328X(00)84929-3.
  11. ↑ Pályi, G.; Baumgartner, F.; Czájlik, I. (1973). "Methynyltricobalt enneacarbonyl compounds". Journal of Organometallic Chemistry. 49 (2): C85–C87. doi:10.1016/S0022-328X(00)84216-3.
  12. ↑ Seyferth, Dietmar; Hallgren, John E.; Spohn, Ralph J.; Williams, Gary H.; Nestle, Mara O.; Hung, Paul L.K. (1974). "Organocobalt cluster complexes". Journal of Organometallic Chemistry. 65: 99–118. doi:10.1016/S0022-328X(00)83893-0.
  13. ↑ Kotz, John C.; Petersen, James V.; Reed, Richard C. (1976). "The electrochemistry of some alkylidynetricobalt nonacarbonyl cluster complexes". Journal of Organometallic Chemistry. 120 (3): 433–437. doi:10.1016/S0022-328X(00)98054-9.
  14. 1 2 Sugihara, Takumichi; Yamaguchi, Masahiko (1998). "The Pauson−Khand Reaction Catalyzed by the Methylidynetricobalt Nonacarbonyl Cluster". Journal of the American Chemical Society. 120 (41): 10782–10783. doi:10.1021/ja982635s.
  15. ↑ Mottalib, M. Abdul; Haukka, Matti; Nordlander, Ebbe (2016). "Chiral diphosphine derivatives of alkylidyne tricobalt carbonyl clusters – A comparative study of different cobalt carbonyl (Pre)catalysts for (Asymmetric) intermolecular Pauson–Khand reactions". Polyhedron. 103: 275–282. doi:10.1016/j.poly.2015.04.021.
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