Rhodium acetate is the chemical compound

Chemical compound

A chemical compound is a pure chemical substance consisting of two or more different chemical elements that can be separated into simpler substances by chemical reactions. Chemical compounds have a unique and defined chemical structure; they consist of a fixed ratio of atoms that are held together...

 with the formula

Chemical formula

A chemical formula or molecular formula is a way of expressing information about the atoms that constitute a particular chemical compound....

 Rh

RH

RH, Rh, rH, or rh can stand for:* Riemann hypothesis, an important unsolved problem in mathematics* Ryan's Hope, a soap opera* Rhesus factor, a classification to describe blood types in humans* Rhodium, a chemical element...

₂(AcO)₄, where AcO⁻ is the acetate

Acetate

An acetate is a derivative of acetic acid. This term includes salts and esters, as well as the anion found in solution. Most of the approximately 5 billion kilograms of acetic acid produced annually in industry are used in the production of acetates, which usually take the form of polymers. In...

 ion (CH₃CO₂⁻). This emerald green powder is a catalyst for cyclopropanation of alkene

Alkene

In organic chemistry, an alkene, olefin, or olefine is an unsaturated chemical compound containing at least one carbon-to-carbon double bond...

s. It is also used as catalyst for insertion into C-H and X-H bonds (X = N/S/O) and for ylide

Ylide

An ylide or ylid is a neutral dipolar molecule containing a formally negatively charged atom directly attached to a hetero atom with a formal positive charge , and in which both atoms have full octets of electrons. Ylides are thus 1,2-dipolar compounds...

 formation for organic syntheses

Organic Syntheses

Organic Syntheses is a scientific journal that since 1921 has provided the chemistry community with annual collections of detailed and checked procedures for the organic synthesis of organic compounds. The journal is peer reviewed...

.

Preparation

Rhodium(II) acetate is usually prepared by the heating hydrated rhodium(III) chloride

Rhodium(III) chloride

Rhodium chloride refers to inorganic compounds with the formula RhCl3n, where n varies from 0 to 3. These are diamagnetic solids featuring octahedral Rh centres. Depending on the value of n, the material is either a dense brown solid or a soluble reddish salt...

 in acetic acid

Acetic acid

Acetic acid is an organic compound with the chemical formula CH3CO2H . It is a colourless liquid that when undiluted is also called glacial acetic acid. Acetic acid is the main component of vinegar , and has a distinctive sour taste and pungent smell...

 (CH₃COOH): Rhodium(II) acetate dimer undergoes ligand exchange, the replacement of the acetate group by other carboxylates and related groups.

Rh₂(OAc)₄ + 4 HO₂Y → Rh₂(O₂Y)₄ + 4 HOAc

Structure and Properties

The structure of rhodium(II) acetate features a pair of rhodium

Rhodium

Rhodium is a chemical element that is a rare, silvery-white, hard and chemically inert transition metal and a member of the platinum group. It has the chemical symbol Rh and atomic number 45. It is composed of only one isotope, 103Rh. Naturally occurring rhodium is found as the free metal, alloyed...

 atoms, each with octahedral molecular geometry

Octahedral molecular geometry

In chemistry, octahedral molecular geometry describes the shape of compounds where in six atoms or groups of atoms or ligands are symmetrically arranged around a central atom, defining the vertices of an octahedron...

, defined by four acetate oxygen atoms, a water ligand, and a Rh-Rh bond (2.39 Å.. Copper(II) acetate

Copper(II) acetate

Copper acetate, also referred to as cupric acetate, is the chemical compound with the formula Cu2 where OAc- is acetate . The hydrated derivative, which contains one molecule of water for each Cu atom, is available commercially. Anhydrous Cu2 is a dark green crystalline solid, whereas Cu22 is...

 and chromium(II) acetate

Chromium(II) acetate

Chromium acetate hydrate, also known as chromous acetate, is the coordination compound with the formula Cr242. This formula is commonly abbreviated Cr242. This red-coloured compound features a quadruple bond...

 adopt similar structures.

Chemical Properties

The application of dirhodium tetraacetate to organic synthesis was pioneered by Teyssie and co-workers. A extensive library of successful transformations rapidly evolved, ranging from Rh(II)-catalyzed OH and NH insertions to cyclopropanation of olefins and aromatic systems. Nowadays, it is used mainly as a catalyst. It can help distinguish between ribonucleosides and deoxynucleosides by binding selectively to ribonucleosides at their 2' and 3' OH groups. Rhodium(II) acetate dimer, compared to copper(II) acetate, is more reactive and useful in differentiating ribonucleosides and deoxynucleosides because it is soluble in aqueous solution like water whereas copper(II) acetate only dissolves in non-aqueous solution.

Selected catalytic reactions

1. Cyclopropanation

through the decomposition

Decomposition

Decomposition is the process by which organic material is broken down into simpler forms of matter. The process is essential for recycling the finite matter that occupies physical space in the biome. Bodies of living organisms begin to decompose shortly after death...

 of diazocarbonyl compounds, the intra- and intermolecular cyclopropanation reactions occurs.

2. Aromatic cycloaddition

Rhodium acetate is a very efficient catalyst for two-component cycloaddition

Cycloaddition

A cycloaddition is a pericyclic chemical reaction, in which "two or more unsaturated molecules combine with the formation of a cyclic adduct in which there is a net reduction of the bond multiplicity." The resulting reaction is a cyclization reaction.Cycloadditions are usually described by the...

 as well as three-component 1,3-dipolar cycloaddition reactions.

3. C-H insertion

Rh(II)-catalyzed regioselective intramolecular and regiospecific intermolecular C-H insertion

Carbene C-H insertion

Carbene C−H insertion in organic chemistry concerns the insertion reaction of a carbene into a carbon–hydrogen bond. This organic reaction is of some importance in the synthesis of new organic compounds . Simple carbenes such as methylene and dichlorocarbene are not regioselective towards...

 into aliphatic and aromatic C-H bonds is a useful method for the synthesis of a diverse range of organic compounds.

4. Oxidation of alcohols

Allylic and benzylic alcohols were oxidized to the corresponding carbonyl compounds using tert-butyl hydroperoxide in stoichiometric amounts and Rh₂(OAc)₄ as catalyst in dichloromethane

Dichloromethane

Dichloromethane is an organic compound with the formula CH2Cl2. This colorless, volatile liquid with a moderately sweet aroma is widely used as a solvent. Although it is not miscible with water, it is miscible with many organic solvents...

 at ambient temperature.

5. X-H insertion (X = N/S/O)

Rh(II) carbenoid

Carbenoid

In chemistry a carbenoid is a reactive intermediate that shares reaction characteristics with a carbene. In the Simmons-Smith reaction the carbenoid intermediate is a zinc / iodine complex that takes the form of...

 reacts with amine

Amine

Amines are organic compounds and functional groups that contain a basic nitrogen atom with a lone pair. Amines are derivatives of ammonia, wherein one or more hydrogen atoms have been replaced by a substituent such as an alkyl or aryl group. Important amines include amino acids, biogenic amines,...

s, alcohols or thiols to yield the product of a formal intra- or intermolecular X-H bond (X = N/O/S) insertion via the formation of an ylide

Ylide

An ylide or ylid is a neutral dipolar molecule containing a formally negatively charged atom directly attached to a hetero atom with a formal positive charge , and in which both atoms have full octets of electrons. Ylides are thus 1,2-dipolar compounds...

 intermediate

Intermediate

Intermediate means "occurring between two extremes, or in the middle of a range". It comes from the Latin word 'intermedia' which literally means 'among the middle' and may refer to:...

.