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.
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.
Molybdenum(V) chloride is the inorganic compound with the empirical formula MoCl5. This dark volatile solid is used in research to prepare other molybdenum compounds. It is moisture-sensitive and soluble in chlorinated solvents.
In coordination chemistry, hapticity is the coordination of a ligand to a metal center via an uninterrupted and contiguous series of atoms. The hapticity of a ligand is described with the Greek letter η ('eta'). For example, η2 describes a ligand that coordinates through 2 contiguous atoms. In general the η-notation only applies when multiple atoms are coordinated. In addition, if the ligand coordinates through multiple atoms that are not contiguous then this is considered denticity, and the κ-notation is used once again. When naming complexes care should be taken not to confuse η with μ ('mu'), which relates to bridging ligands.
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).
In organometallic chemistry, a sandwich compound is a chemical compound featuring a metal bound by haptic, covalent bonds to two arene (ring) ligands. The arenes have the formula CnHn, substituted derivatives and heterocyclic derivatives. Because the metal is usually situated between the two rings, it is said to be "sandwiched". A special class of sandwich complexes are the metallocenes.
Tungsten hexacarbonyl (also called tungsten carbonyl) is an organometallic compound with the formula W(CO)6. This complex gave rise to the first example of a dihydrogen complex.
Dicarbonylbis(cyclopentadienyl)titanium is the chemical compound with the formula (η5-C5H5)2Ti(CO)2, abbreviated Cp2Ti(CO)2. This maroon-coloured, air-sensitive species is soluble in aliphatic and aromatic solvents. It has been used for the deoxygenation of sulfoxides, reductive coupling of aromatic aldehydes and reduction of aldehydes.
In organometallic chemistry, a transition metal indenyl complex is a coordination compound that contains one or more indenyl ligands. The indenyl ligand is formally the anion derived from deprotonation of indene. The η5-indenyl ligand is related to the η5cyclopentadienyl anion (Cp), thus indenyl analogues of many cyclopentadienyl complexes are known. Indenyl ligands lack the 5-fold symmetry of Cp, so they exhibit more complicated geometries. Furthermore, some indenyl complexes also exist with only η3-bonding mode. The η5- and η3-bonding modes sometimes interconvert.
Cyclopentadienylcobalt dicarbonyl is an organocobalt compound with formula (C5H5)Co(CO)2, abbreviated CpCo(CO)2. It is an example of a half-sandwich complex. It is a dark red air sensitive liquid. This compound features one cyclopentadienyl ring that is bound in an η5-manner and two carbonyl ligands. The compound is soluble in common organic solvents.
Organomolybdenum chemistry is the chemistry of chemical compounds with Mo-C bonds. The heavier group 6 elements molybdenum and tungsten form organometallic compounds similar to those in organochromium chemistry but higher oxidation states tend to be more common.
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.
Molybdocene dichloride is the organomolybdenum compound with the formula (η5-C5H5)2MoCl2 and IUPAC name dichlorobis(η5-cyclopentadienyl)molybdenum(IV), and is commonly abbreviated as Cp2MoCl2. It is a brownish-green air- and moisture-sensitive powder. In the research laboratory, it is used to prepare many derivatives.
Cyclopentadienyliron dicarbonyl dimer is an organometallic compound with the formula [(η5-C5H5)Fe(CO)2]2, often abbreviated to Cp2Fe2(CO)4, [CpFe(CO)2]2 or even Fp2, with the colloquial name "fip dimer". It is a dark reddish-purple crystalline solid, which is readily soluble in moderately polar organic solvents such as chloroform and pyridine, but less soluble in carbon tetrachloride and carbon disulfide. Cp2Fe2(CO)4 is insoluble in but stable toward water. Cp2Fe2(CO)4 is reasonably stable to storage under air and serves as a convenient starting material for accessing other Fp (CpFe(CO)2) derivatives (described below).
Half sandwich compounds, also known as piano stool complexes, are organometallic complexes that feature a cyclic polyhapto ligand bound to an MLn center, where L is a unidentate ligand. Thousands of such complexes are known. Well-known examples include cyclobutadieneiron tricarbonyl and (C5H5)TiCl3. Commercially useful examples include (C5H5)Co(CO)2, which is used in the synthesis of substituted pyridines, and methylcyclopentadienyl manganese tricarbonyl, an antiknock agent in petrol.
trans-Bis(dinitrogen)bis[1,2-bis(diphenylphosphino)ethane]molybdenum(0) is a coordination complex with the formula Mo(N2)2(dppe)2. It is a relatively air stable yellow-orange solid. It is notable as being the first discovered dinitrogen containing complex of molybdenum.
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.
Transition metal nitrile complexes are coordination compounds containing nitrile ligands. Because nitriles are weakly basic, the nitrile ligands in these complexes are often labile.
Cyclopentadienyltungsten tricarbonyl dimer is the organotungsten compound with the formula Cp2W2(CO)6, where Cp is C5H5. A dark red crystalline solid, it is the subject of research, although it has no or few practical uses.
Cyclopentadienylchromium tricarbonyl dimer is the organochromium compound with the formula Cp2Cr2(CO)6, where Cp is C5H5. A dark green crystalline solid. It is the subject of research it exists in measureable equilibrium quantities with the monometallic radical CpCr(CO)3.
