Tris(dibenzylideneacetone)dipalladium(0)

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Tris(dibenzylideneacetone)dipalladium(0)
Pd2(dba)3.png
Tris(dibenzylideneacetone)dipalladium(0)-3D-balls.png
Names
IUPAC name
Tris(dibenzylideneacetone)dipalladium
Other names
Pd2(dba)3
Identifiers
ECHA InfoCard 100.122.794
PubChem CID
Properties
C51H42O3Pd2
Molar mass 915.73 g·mol−1
Melting point 152 to 155 °C (306 to 311 °F; 425 to 428 K)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

Tris(dibenzylideneacetone)dipalladium(0) or [Pd2(dba)3] is an organopalladium compound. The compound is a complex of palladium(0) with dibenzylideneacetone (dba). It is a dark-purple/brown solid, which is modestly soluble in organic solvents. Because the dba ligands are easily displaced, the complex is used as a homogeneous catalyst in organic synthesis. [1]

Palladium Chemical element with atomic number 46

Palladium is a chemical element with symbol Pd and atomic number 46. It is a rare and lustrous silvery-white metal discovered in 1803 by William Hyde Wollaston. He named it after the asteroid Pallas, which was itself named after the epithet of the Greek goddess Athena, acquired by her when she slew Pallas. Palladium, platinum, rhodium, ruthenium, iridium and osmium form a group of elements referred to as the platinum group metals (PGMs). These have similar chemical properties, but palladium has the lowest melting point and is the least dense of them.

Dibenzylideneacetone chemical compound

Dibenzylideneacetone or dibenzalacetone, often abbreviated dba, is an organic compound with the formula C17H14O. It is a pale-yellow solid insoluble in water, but soluble in ethanol. Dibenzylideneacetone is used as a component in sunscreens and as a ligand in organometallic chemistry.

Organic synthesis is a special branch of chemical synthesis and is concerned with the intentional construction of organic compounds. Organic molecules are often more complex than inorganic compounds, and their synthesis has developed into one of the most important branches of organic chemistry. There are several main areas of research within the general area of organic synthesis: total synthesis, semisynthesis, and methodology.

Contents

Preparation and structure

Pd2(dba)3 Tris(dibenzylideneacetone)dipalladium(0).jpg
Pd2(dba)3

First reported in 1970, [2] it is prepared from dibenzylideneacetone and sodium tetrachloropalladate. Because it is commonly recrystallized from chloroform, the complex is often supplied as the adduct [Pd2(dba)3·CHCl3]. [1] The purity of samples can be variable. [3]

Sodium tetrachloropalladate is an inorganic compound with the chemical formula Na2PdCl4. This salt, and the analogous alkali metal salts of the form M2PdCl4, may be prepared simply by reacting palladium(II) chloride with the appropriate alkali metal chloride in aqueous solution. Palladium(II) chloride is insoluble in water, whereas the product dissolves:

In [Pd2(dba)3], the pair of Pd atoms are separated by 320  pm but are tied together by dba units. [4] The Pd(0) centres are bound to the alkene parts of the dba ligands.

Ligand molecule or functional group that binds or can bind to the central atom in a coordination complex

In coordination chemistry, a ligand is an ion or molecule that binds to a central metal atom to form a coordination complex. The bonding with the metal generally involves formal donation of one or more of the ligand's electron pairs. The nature of metal–ligand bonding can range from covalent to ionic. Furthermore, the metal–ligand bond order can range from one to three. Ligands are viewed as Lewis bases, although rare cases are known to involve Lewis acidic "ligands".

Applications

[Pd2(dba)3] is used as a source of soluble Pd(0), in particular as a catalyst for various coupling reactions. Examples of reactions using this reagent are the Negishi coupling, Suzuki coupling, Carroll rearrangement, and Trost asymmetric allylic alkylation, as well as Buchwald–Hartwig amination. [5]

The Negishi coupling is a widely employed transition metal catalyzed cross-coupling reaction. The reaction couples organic halides or triflates with organozinc compounds, forming carbon-carbon bonds (c-c) in the process. A palladium (0) species is generally utilized as the metal catalyst, though nickel is sometimes used:

The Carroll rearrangement is a rearrangement reaction in organic chemistry and involves the transformation of a β-keto allyl ester into a α-allyl-β-ketocarboxylic acid. This organic reaction is accompanied by decarboxylation and the final product is a γ,δ-allylketone. The Carroll rearrangement is an adaptation of the Claisen rearrangement and effectively a decarboxylative Allylation.

The Buchwald–Hartwig amination is a chemical reaction used in organic chemistry for the synthesis of carbon–nitrogen bonds via the Palladium-catalyzed coupling reactions of amines with aryl halides. Although Pd-catalyzed C-N couplings were reported as early as 1983, Stephen L. Buchwald and John F. Hartwig have been credited, whose publications between 1994 and the late 2000s established the scope of the transformation. The reaction's synthetic utility stems primarily from the shortcomings of typical methods for the synthesis of aromatic C–N bonds, with most methods suffering from limited substrate scope and functional group tolerance. The development of the Buchwald–Hartwig reaction allowed for the facile synthesis of aryl amines, replacing to an extent harsher methods while significantly expanding the repertoire of possible C–N bond formation.

Related Pd(0) complexes are [Pd(dba)2] [6] and tetrakis(triphenylphosphine)palladium(0).

Tetrakis(triphenylphosphine)palladium(0) chemical compound

Tetrakis(triphenylphosphine)palladium(0) (sometimes called quatrotriphenylphosphine) is the chemical compound Pd[P(C6H5)3]4, often abbreviated Pd(PPh3)4, or rarely PdP4. It is a bright yellow crystalline solid that becomes brown upon decomposition in air.

Related Research Articles

The Suzuki reaction is an organic reaction, classified as a coupling reaction, where the coupling partners are a boronic acid and an organohalide catalyzed by a palladium(0) complex. It was first published in 1979 by Akira Suzuki and he shared the 2010 Nobel Prize in Chemistry with Richard F. Heck and Ei-ichi Negishi for their effort for discovery and development of palladium-catalyzed cross couplings in organic synthesis. In many publications this reaction also goes by the name Suzuki–Miyaura reaction and is also referred to as the Suzuki coupling. It is widely used to synthesize poly-olefins, styrenes, and substituted biphenyls. Several reviews have been published describing advancements and the development of the Suzuki Reaction. The general scheme for the Suzuki reaction is shown below where a carbon-carbon single bond is formed by coupling an organoboron species (R1-BY2) with a halide (R2-X) using a palladium catalyst and a base.

The Sonogashira reaction is a cross-coupling reaction used in organic synthesis to form carbon–carbon bonds. It employs a palladium catalyst as well as copper co-catalyst to form a carbon–carbon bond between a terminal alkyne and an aryl or vinyl halide.

A coupling reaction in organic chemistry is a general term for a variety of reactions where two fragments are joined together with the aid of a metal catalyst. In one important reaction type, a main group organometallic compound of the type R-M reacts with an organic halide of the type R'-X with formation of a new carbon-carbon bond in the product R-R'

Organopalladium chemistry is a branch of organometallic chemistry that deals with organic palladium compounds and their reactions. Palladium is often used as a catalyst in the reduction of alkenes and alkynes with hydrogen. This process involves the formation of a palladium-carbon covalent bond. Palladium is also prominent in carbon-carbon coupling reactions, as demonstrated in tandem reactions.

Nanomaterial-based catalysts are usually heterogeneous catalysts broken up into metal nanoparticles in order to speed up the catalytic process. Metal nanoparticles have a higher surface area so there is increased catalytic activity because more catalytic reactions can occur at the same time. Nanoparticle catalysts can also be easily separated and recycled with more retention of catalytic activity than their bulk counterparts. These catalysts can play two different roles in catalytic processes: they can be the site of catalysis or they can act as a support for catalytic processes. They are typically used under mild conditions to prevent decomposition of the nanoparticles at extreme conditions.

In organic chemistry, the Kumada coupling is a type of cross coupling reaction, useful for generating carbon–carbon bonds by the reaction of a Grignard reagent and an organic halide. The procedure uses transition metal catalysts, typically nickel or palladium, to couple a combination of two alkyl, aryl or vinyl groups. The groups of Robert Corriu and Makoto Kumada reported the reaction independently in 1972.

Bis(triphenylphosphine)palladium chloride chemical compound

Bis(triphenylphosphine)palladium chloride is a coordination compound of palladium containing two triphenylphosphine and two chloride ligands. It is a yellow solid that is soluble in some organic solvents. It is used for palladium-catalyzed coupling reactions, e.g. the Sonogashira–Hagihara reaction. The complex is square planar. Both cis and trans isomers are known, but the cis isomer is more common. Many analogous complexes are known with different phosphine ligands.

Palladium-catalyzed coupling reactions

Palladium-catalyzed coupling reactions comprise a family of cross-coupling reactions that employ palladium complexes as catalysts. It is an active area of research and applications in homogeneous catalysis. In 2010, the Nobel Prize in Chemistry was awarded to Richard F. Heck, Ei-ichi Negishi and Akira Suzuki for their work on palladium-catalyzed cross couplings in organic synthesis.

Dichlorotris(triphenylphosphine)ruthenium(II) 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.

Dichloro(1,3-bis(diphenylphosphino)propane)nickel chemical compound

Dichloro[1,3-bis(diphenylphosphino)propane]nickel a coordination complex with the formula NiCl2(dppp); where dppp is the diphosphine 1,3-bis(diphenylphosphino)propane. It is used as a catalyst in organic synthesis. The compound is a bright orange-red crystalline powder.

Bis(acetonitrile)palladium dichloride

Bis(acetonitrile)palladium dichloride is the coordination complex with the formula PdCl2(NCCH3)2. It is the adduct of two acetonitrile ligands with palladium(II) chloride. It is a yellow-brown solid that is soluble in organic solvents. The compound is a reagent and a catalyst for reactions that require soluble Pd(II). The compound is similar to bis(benzonitrile)palladium dichloride. It reacts with 1,5-cod to give dichloro(1,5‐cyclooctadiene)palladium.

(1,1-Bis(diphenylphosphino)ferrocene)palladium(II) dichloride chemical compound

[1,1'-Bis(diphenylphosphino)ferrocene]palladium(II) dichloride is a palladium complex containing the bidentate ligand 1,1'-bis(diphenylphosphino)ferrocene (dppf), abbreviated as [(dppf)PdCl2]. This commercially available material can be prepared by reacting dppf with a suitable nitrile complex of palladium dichloride:

Metal acetylacetonates are coordination complexes derived from the acetylacetonate anion (CH
3
COCHCOCH
2
) and metal ions, usually transition metals. The bidentate ligand acetylacetonate is often abbreviated acac. Typically both oxygen atoms bind to the metal to form a six-membered chelate ring. The simplest complexes have the formula M(acac)3 and M(acac)2. Mixed-ligand complexes, e.g. VO(acac)2, are also numerous. Variations of acetylacetonate have also been developed with myriad substituents in place of methyl (RCOCHCOR′). Many such complexes are soluble in organic solvents, in contrast to the related metal halides. Because of these properties, acac complexes are sometimes used as catalyst precursors and reagents. Applications include their use as NMR "shift reagents" and as catalysts for organic synthesis, and precursors to industrial hydroformylation catalysts. C
5
H
7
O
2
in some cases also binds to metals through the central carbon atom; this bonding mode is more common for the third-row transition metals such as platinum(II) and iridium(III).

Heck–Matsuda reaction

The Heck-Matsuda (HM) reaction is an organic reaction and a type of palladium catalysed arylation of olefins that uses arenediazonium salts as an alternative to aryl halides and triflates.

Metal phosphine complex

In coordination chemistry phosphines are L-type ligands. Unlike most metal ammine complexes, metal phosphine complexes tend to be lipophilic, displaying good solubility in organic solvents. They also are compatible with metals in multiple oxidation states. Because of these two features, 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).

Early transition metal pincer complexes

A pincer ligand is a class of chelating ligand which occupies three coordination sites of a transition metal or other coordinatively unsaturated species. The ligand often occupies a meridional orientation on the metal centre due to its planarity. This invokes a planar geometry at the metal centre for three of the coordination sites.

Palladium–NHC complex

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.

Bis(benzonitrile)palladium dichloride chemical compound

Bis(benzonitrile)palladium dichloride is the coordination complex with the formula PdCl2(NCC6H5)2. It is the adduct of two benzonitrile (PhCN) ligands with palladium(II) chloride. It is a yellow-brown solid that is soluble in organic solvents. The compound is a reagent and a precatalyst for reactions that require soluble Pd(II). A closely related compound is bis(acetonitrile)palladium dichloride.

References

  1. 1 2 Jiro Tsuji and Ian J. S. Fairlamb "Tris(dibenzylideneacetone)dipalladium–Chloroform" E-EROS, 2008. doi : 10.1002/047084289X.rt400.pub2
  2. Takahashi, Y.; Ito, Ts.; Sakai, S.; Ishii, Y. (1970). "A novel palladium(0) complex; bis(dibenzylideneacetone)palladium(0)". Journal of the Chemical Society D: Chemical Communications (17): 1065. doi:10.1039/C29700001065.
  3. Zalesskiy, S. S., Ananikov, V. P., "Pd2(dba)3 as a Precursor of Soluble Metal Complexes and Nanoparticles: Determination of Palladium Active Species for Catalysis and Synthesis", Organometallics 2012, 31, 2302. doi : 10.1021/om201217r
  4. Pierpont, Cortlandt G.; Mazza, Margaret C. (1974). "Crystal and molecular structure of tris(dibenzylideneacetone)dipalladium(0)". Inorg. Chem. 13 (8): 1891. doi:10.1021/ic50138a020.
  5. Hartwig, J. F. (2010). Organotransition Metal Chemistry, from Bonding to Catalysis. New York: University Science Books. ISBN   1-891389-53-X.
  6. John R. Stille, F. Christopher Pigge, Christopher S. Regens, Ke Chen, Adrian Ortiz and Martin D. Eastgate "Bis(dibenzylideneacetone)palladium(0)" E-eros. 2013. doi : 10.1002/047084289X.rb138.pub3