A transition metal carbene complex is an organometallic compound featuring a divalent carbon ligand, itself also called a carbene. Carbene complexes have been synthesized from most transition metals and f-block metals, using many different synthetic routes such as nucleophilic addition and alpha-hydrogen abstraction. The term carbene ligand is a formalism since many are not directly derived from carbenes and most are much less reactive than lone carbenes. Described often as =CR2, carbene ligands are intermediate between alkyls (−CR3) and carbynes (≡CR). Many different carbene-based reagents such as Tebbe's reagent are used in synthesis. They also feature in catalytic reactions, especially alkene metathesis, and are of value in both industrial heterogeneous and in homogeneous catalysis for laboratory- and industrial-scale preparation of fine chemicals.
Chromium hexacarbonyl is a chromium(0) organometallic compound with the formula Cr(CO)6. It is a homoleptic complex, which means that all the ligands are identical. It is a colorless crystalline air-stable solid, with a high vapor pressure.
Robert Howard Crabtree is a British-American chemist. He is serving as Conkey P. Whitehead Professor Emeritus of Chemistry at Yale University in the United States. He is a naturalized citizen of the United States. Crabtree is particularly known for his work on "Crabtree's catalyst" for hydrogenations, and his textbook on organometallic chemistry.
Vanadium(III) chloride describes the inorganic compound with the formula VCl3 and its hydrates. It forms a purple anhydrous form and a green hexahydrate [VCl2(H2O)4]Cl·2H2O. These hygroscopic salts are common precursors to other vanadium(III) complexes and is used as a mild reducing agent.
Organotitanium chemistry is the science of organotitanium compounds describing their physical properties, synthesis, and reactions. Organotitanium compounds in organometallic chemistry contain carbon-titanium chemical bonds. They are reagents in organic chemistry and are involved in major industrial processes.
Organoscandium chemistry is an area with organometallic compounds focused on compounds with at least one carbon to scandium chemical bond. The interest in organoscandium compounds is mostly academic but motivated by potential practical applications in catalysis, especially in polymerization. A common precursor is scandium chloride, especially its THF complex.
Organovanadium chemistry is the chemistry of organometallic compounds containing a carbon (C) to vanadium (V) chemical bond. Organovanadium compounds find only minor use as reagents in organic synthesis but are significant for polymer chemistry as catalysts.
Organosilver chemistry is the study of organometallic compounds containing a carbon to silver chemical bond. The theme is less developed than organocopper chemistry.
Organorhenium chemistry describes the compounds with Re−C bonds. Because rhenium is a rare element, relatively few applications exist, but the area has been a rich source of concepts and a few useful catalysts.
A transition metal oxo complex is a coordination complex containing an oxo ligand. Formally O2-, an oxo ligand can be bound to one or more metal centers, i.e. it can exist as a terminal or (most commonly) as bridging ligands (Fig. 1). Oxo ligands stabilize high oxidation states of a metal. They are also found in several metalloproteins, for example in molybdenum cofactors and in many iron-containing enzymes. One of the earliest synthetic compounds to incorporate an oxo ligand is potassium ferrate (K2FeO4), which was likely prepared by Georg E. Stahl in 1702.
Vanadocene, bis(η5-cyclopentadienyl) vanadium, is the organometallic compound with the formula V(C5H5)2, commonly abbreviated Cp2V. It is a violet crystalline, paramagnetic solid. Vanadocene has relatively limited practical use, but it has been extensively studied.
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).
Tetramesityldiiron is an organoiron compound with the formula Fe2(C6H2(CH3)3)4. It is a red, air-sensitive solid that is used as a precursor to other iron complexes. It adopts a centrosymmetric structure. The complex is a Lewis acid, forming monomeric adducts, e.g. Fe(C6H2(CH3)3)2pyridine2. The complex is prepared by treating ferrous halides with the Grignard reagent formed from mesityl bromide:
Transition metal alkyl complexes are coordination complexes that contain a bond between a transition metal and an alkyl ligand. Such complexes are not only pervasive but are of practical and theoretical interest.
William J. Evans is a Distinguished Professor at the University of California, Irvine, who specializes in the inorganic and organometallic chemistry of heavy metals, specifically the rare earth metals, actinides, and bismuth. He has published over 500 peer-reviewed research papers on these topics.
Bis(cyclopentadienyl)titanium(III) chloride, also known as the Nugent–RajanBabu reagent, is the organotitanium compound which exists as a dimer with the formula [(C5H5)2TiCl]2. It is an air sensitive green solid. The complex finds specialized use in synthetic organic chemistry as a single electron reductant.
Hexa(tert-butoxy)ditungsten(III) is a coordination complex of tungsten(III). It is one of the homoleptic alkoxides of tungsten. A red, air-sensitive solid, the complex has attracted academic attention as the precursor to many organotungsten derivatives. It an example of a charge-neutral complex featuring a W≡W bond, arising from the coupling of a pair of d3 metal centers.
Marinella Mazzanti is an Italian inorganic chemist specialized in coordination chemistry. She is a professor at EPFL and the head of the group of Coordination Chemistry at EPFL's School of Basic Sciences.
Homoleptic tetra-mesityl complexes of transition metal (IV), denoted as M(mes)4, constitute a category of organometallic substances that remain relatively unexplored. Characterized by tetrahedral coordination geometry, these compounds exhibit distinctive electrochemical, magnetic, and optical properties. Their unique attributes surpass those of their isostructural counterparts in group 14, commonly employed as fundamental components in advanced molecular materials like covalent- and metal–organic frameworks, polymers, self-assembled monolayers, and single-molecule electronic devices. Recent advancements, showcase the potential of modular, isostructural M(aryl) units in providing novel avenues for adjusting the electrochemical energy storage capacity, electrocatalytic functionality, and electrical conductivity/conductance of such materials, opening up various applications.
Tris(silox)tantalum, Ta(SiOtBu3)3, is an organotantalum complex bound with three siloxide (this siloxide has three tert-butyl groups attached to silicon, attached via oxygen (tBu3SiO-)) ligands. The tantalum center has a d-electron count of 2 and an oxidation state of III. The complex is trigonal planar whose point group is assigned as D3h. It is a crystalline light blue solid which forms blue-green solutions in tetrahydrofuran (THF).
