A metallocene is a compound typically consisting of two cyclopentadienyl anions (C
5H−
5, abbreviated Cp) bound to a metal center (M) in the oxidation state II, with the resulting general formula (C5H5)2M. Closely related to the metallocenes are the metallocene derivatives, e.g. titanocene dichloride or vanadocene dichloride. Certain metallocenes and their derivatives exhibit catalytic properties, although metallocenes are rarely used industrially. Cationic group 4 metallocene derivatives related to [Cp2ZrCH3]+ catalyze olefin polymerization.
Ferrocene is an organometallic compound with the formula Fe(C5H5)2. The molecule is a complex consisting of two cyclopentadienyl rings bound to a central iron atom. It is an orange solid with a camphor-like odor, that sublimes above room temperature, and is soluble in most organic solvents. It is remarkable for its stability: it is unaffected by air, water, strong bases, and can be heated to 400 °C without decomposition. In oxidizing conditions it can reversibly react with strong acids to form the ferrocenium cation Fe(C5H5)+2. Ferrocene and the ferrocenium cation are sometimes abbreviated as Fc and Fc+ respectively.
Cyclopentadiene is an organic compound with the formula C5H6. It is often abbreviated CpH because the cyclopentadienyl anion is abbreviated Cp−.
A cyclopentadienyl complex is a coordination complex of a metal and cyclopentadienyl groups. Cyclopentadienyl ligands almost invariably bind to metals as a pentahapto (η5-) bonding mode. The metal–cyclopentadienyl interaction is typically drawn as a single line from the metal center to the center of the Cp ring.
Nickelocene is the organonickel compound with the formula Ni(η5-C5H5)2. Also known as bis(cyclopentadienyl)nickel or NiCp2, this bright green paramagnetic solid is of enduring academic interest, although it does not yet have any known practical applications.
Cobaltocene, known also as bis(cyclopentadienyl)cobalt(II) or even "bis Cp cobalt", is an organocobalt compound with the formula Co(C5H5)2. It is a dark purple solid that sublimes readily slightly above room temperature. Cobaltocene was discovered shortly after ferrocene, the first metallocene. Due to the ease with which it reacts with oxygen, the compound must be handled and stored using air-free techniques.
Titanocene dichloride is the organotitanium compound with the formula (η5-C5H5)2TiCl2, commonly abbreviated as Cp2TiCl2. This metallocene is a common reagent in organometallic and organic synthesis. It exists as a bright red solid that slowly hydrolyzes in air. It shows antitumour activity and was the first non-platinum complex to undergo clinical trials as a chemotherapy drug.
Chromocene is the organochromium compound with the formula [Cr(C5H5)2]. Like structurally related metallocenes, chromocene readily sublimes in a vacuum and is soluble in non-polar organic solvents. It is more formally known as bis(η5-cyclopentadienyl)chromium(II).
Ruthenocene is an organoruthenium compound with the formula (C5H5)2Ru. This pale yellow, volatile solid is classified as a sandwich compound and more specifically, as a metallocene.
Sodium cyclopentadienide is an organosodium compound with the formula C5H5Na. The compound is often abbreviated as NaCp, where Cp− is the cyclopentadienide anion. Sodium cyclopentadienide is a colorless solid, although samples often are pink owing to traces of oxidized impurities.
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. While iron adopts oxidation states from Fe(−II) through to Fe(VII), Fe(IV) is the highest established oxidation state for organoiron species. 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.
Organosodium chemistry is the chemistry of organometallic compounds containing a carbon to sodium chemical bond. The application of organosodium compounds in chemistry is limited in part due to competition from organolithium compounds, which are commercially available and exhibit more convenient reactivity.
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.
Manganocene or bis(cyclopentadienyl)manganese(II) is an organomanganese compound with the formula [Mn(C5H5)2]n. It is a thermochromic solid that degrades rapidly in air. Although the compound is of little utility, it is often discussed as an example of a metallocene with ionic character.
Osmocene is an organoosmium compound found as a white solid. It is a metallocene with the formula Os(C5H5)2.
In organometallic chemistry, bent metallocenes are a subset of metallocenes. In bent metallocenes, the ring systems coordinated to the metal are not parallel, but are tilted at an angle. A common example of a bent metallocene is Cp2TiCl2. Several reagents and much research is based on bent metallocenes.
Trimethylsilyl cyclopentadiene is an organosilicon compound with the chemical formula C5H5Si(CH3)3. It exists as a colorless liquid. It is used in the synthesis of some metal cyclopentadienyl complexes and has attracted interest for its fluxional structure.
Molybdocene dihydride is the organomolybdenum compound with the formula (η5-C5H5)2MoH2. Commonly abbreviated as Cp2MoH2, it is a yellow air-sensitive solid that dissolves in some organic solvents.
Magnesocene, also known as bis(cyclopentadienyl)magnesium(II) and sometimes abbreviated as MgCp2, is an organometallic compound with the formula Mg(η5-C5H5)2. It is an example of an s-block main group sandwich compound, structurally related to the d-block element metallocenes, and consists of a central magnesium atom sandwiched between two cyclopentadienyl rings.
Lithium cyclopentadienide is an organolithium compound with the formula C5H5Li. The compound is often abbreviated as LiCp, where Cp− is the cyclopentadienide anion. Lithium cyclopentadienide is a colorless solid, although samples often are pink owing to traces of oxidized impurities.
