The Heck reaction is the chemical reaction of an unsaturated halide with an alkene in the presence of a base and a palladium catalyst to form a substituted alkene. It is named after Tsutomu Mizoroki and Richard F. Heck. Heck was awarded the 2010 Nobel Prize in Chemistry, which he shared with Ei-ichi Negishi and Akira Suzuki, for the discovery and development of this reaction. This reaction was the first example of a carbon-carbon bond-forming reaction that followed a Pd(0)/Pd(II) catalytic cycle, the same catalytic cycle that is seen in other Pd(0)-catalyzed cross-coupling reactions. The Heck reaction is a way to substitute alkenes.
Palladium(II) chloride, also known as palladium dichloride and palladous chloride, are the chemical compounds with the formula PdCl2. PdCl2 is a common starting material in palladium chemistry – palladium-based catalysts are of particular value in organic synthesis. It is prepared by the reaction of chlorine with palladium metal at high temperatures.
Cycloocta-1,5-diene is a cyclic hydrocarbon with the chemical formula C8H12, specifically [−(CH2)2−CH=CH−]2.
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. Many analogous complexes are known with different phosphine ligands.
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:
Nickel(II) bis(acetylacetonate) is a coordination complex with the formula [Ni(acac)2]3, where acac is the anion C5H7O2− derived from deprotonation of acetylacetone. It is a dark green paramagnetic solid that is soluble in organic solvents such as toluene. It reacts with water to give the blue-green diaquo complex Ni(acac)2(H2O)2.
Ruthenium(III) acetylacetonate is a coordination complex with the formula Ru(O2C5H7)3. O2C5H7− is the ligand called acetylacetonate. This compound exists as a dark violet solid that is soluble in most organic solvents. It is used as a precursor to other compounds of ruthenium.
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-cyclooctadiene to give dichloro(1,5‐cyclooctadiene)palladium.
Metal acetylacetonates are coordination complexes derived from the acetylacetonate anion (CH
3COCHCOCH−
3) 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
5H
7O−
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).
Vanadyl acetylacetonate is the chemical compound with the formula VO(acac)2, where acac– is the conjugate base of acetylacetone. It is a blue-green solid that dissolves in polar organic solvents. The coordination complex consists of the vanadyl group, VO2+, bound to two acac– ligands via the two oxygen atoms on each. Like other charge-neutral acetylacetonate complexes, it is not soluble in water.
Barium acetylacetonate is a compound with formula Ba(C5H7O2)2. It is the Ba2+ complex of the anion acetylacetonate. The compound is typically encountered as an ill-defined hydrate, which would accord with the high coordination number characteristic of barium.
Iridium acetylacetonate is the iridium coordination complex with the formula Ir(O2C5H7)3, which is sometimes known as Ir(acac)3. The molecule has D3-symmetry. It is a yellow-orange solid that is soluble in organic solvents.
Rhodium acetylacetonate is the coordination complex with the formula Rh(C5H7O2)3, which is sometimes known as Rh(acac)3. The molecule has D3-symmetry. It is a yellow-orange solid that is soluble in organic solvents.
Titanium bis(acetylacetonate)dichloride is the coordination complex with the formula Ti(C5H7O2)2Cl2. It is a common acetylacetonate complex of titanium. It is a red-orange solid that hydrolyzes slowly in air.
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.
Chromium(II) acetylacetonate is the coordination compound with the formula Cr(O2C5H7)2. It is the homoleptic acetylacetonate complex of chromium(II). It is an air-sensitive, paramagnetic yellow brown solid. According to X-ray crystallography, the Cr center is square planar. In contrast to the triplet ground state for this complex, the bis(pyridine) adduct features noninnocent acac2- ligand attached to Cr(III).
Platinum(II) bis(acetylacetonate) is the coordination compound with the formula Pt(O2C5H7)2, abbreviated Pt(acac)2. The homoleptic acetylacetonate complex of platinum(II), it is a yellow, benzene-soluble solid. According to X-ray crystallography, the Pt center is square planar. The compound is a widely used precursor to platinum-based catalysts.
Gallium acetate is a salt composed of a gallium atom trication and three acetate groups as anions where gallium exhibits the +3 oxidation state. It has a chemical formula of Ga(CH3COO)3 although it can be informally referred to as GaAc because Ac is an informal symbol for acetate. Gallium is moderately water-soluble and decomposes to gallium oxide when heated to around 70 °C. Gallium acetate, like other acetate compounds, is a good precursor to ultra-pure compounds, catalysts and nanoscale materials. Gallium acetate is being considered as a substitute in de-icing compounds like calcium chloride and magnesium chloride.
Palladium forms a variety of ionic, coordination, and organopalladium compounds, typically with oxidation state Pd0 or Pd2+. Palladium(III) compounds have also been reported. Palladium compounds are frequently used as catalysts in cross-coupling reactions such as the Sonogashira coupling and Suzuki reaction.
Bis(acetylacetonato)iron(II) is a coordination complex of iron with the formula Fe(C5H7O2)2. It can be prepared by reacting iron(II) chloride with 2,4-pentanedione in presence of piperidine.
