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.
Thallium is a chemical element; it has symbol Tl and atomic number 81. It is a gray post-transition metal that is not found free in nature. When isolated, thallium resembles tin, but discolors when exposed to air. Chemists William Crookes and Claude-Auguste Lamy discovered thallium independently in 1861, in residues of sulfuric acid production. Both used the newly developed method of flame spectroscopy, in which thallium produces a notable green spectral line. Thallium, from Greek θαλλός, thallós, meaning "green shoot" or "twig", was named by Crookes. It was isolated by both Lamy and Crookes in 1862; Lamy by electrolysis, and Crookes by precipitation and melting of the resultant powder. Crookes exhibited it as a powder precipitated by zinc at the international exhibition, which opened on 1 May that year.
In chemistry, a hydride is formally the anion of hydrogen (H−), a hydrogen atom with two electrons. The term is applied loosely. At one extreme, all compounds containing covalently bound H atoms are called hydrides: water (H2O) is a hydride of oxygen, ammonia is a hydride of nitrogen, etc. For inorganic chemists, hydrides refer to compounds and ions in which hydrogen is covalently attached to a less electronegative element. In such cases, the H centre has nucleophilic character, which contrasts with the protic character of acids. The hydride anion is very rarely observed.
Diborane(6), commonly known as diborane, is the chemical compound with the formula B2H6. It is a toxic, colorless, and pyrophoric gas with a repulsively sweet odor. Given its simple formula, borane is a fundamental boron compound. It has attracted wide attention for its electronic structure. Several of its derivatives are useful reagents.
The inert-pair effect is the tendency of the two electrons in the outermost atomic s-orbital to remain unshared in compounds of post-transition metals. The term inert-pair effect is often used in relation to the increasing stability of oxidation states that are two less than the group valency for the heavier elements of groups 13, 14, 15 and 16. The term "inert pair" was first proposed by Nevil Sidgwick in 1927. The name suggests that the outermost s electron pairs are more tightly bound to the nucleus in these atoms, and therefore more difficult to ionize or share.
Borderline hydrides typically refer to hydrides formed of hydrogen and elements of the periodic table in group 11 and group 12 and indium (In) and thallium (Tl). These compounds have properties intermediate between covalent hydrides and saline hydrides. Hydrides are chemical compounds that contain a metal and hydrogen acting as a negative ion.
Aluminium hydride is an inorganic compound with the formula AlH3. Alane and its derivatives are part of a family of common reducing reagents in organic synthesis based around group 13 hydrides. In solution—typically in etherial solvents such tetrahydrofuran or diethyl ether—aluminium hydride forms complexes with Lewis bases, and reacts selectively with particular organic functional groups, and although it is not a reagent of choice, it can react with carbon-carbon multiple bonds. Given its density, and with hydrogen content on the order of 10% by weight, some forms of alane are, as of 2016, active candidates for storing hydrogen and so for power generation in fuel cell applications, including electric vehicles. As of 2006 it was noted that further research was required to identify an efficient, economical way to reverse the process, regenerating alane from spent aluminium product.
Magnesium hydride is the chemical compound with the molecular formula MgH2. It contains 7.66% by weight of hydrogen and has been studied as a potential hydrogen storage medium.
Zinc hydride is an inorganic compound with the chemical formula ZnH2. It is a white, odourless solid which slowly decomposes into its elements at room temperature; despite this it is the most stable of the binary first row transition metal hydrides. A variety of coordination compounds containing Zn–H bonds are used as reducing agents, however ZnH2 itself has no common applications.
Gallane, also systematically named trihydridogallium, is an inorganic compound of gallium with the chemical formula GaH
3. It is a photosensitive, colourless gas that cannot be concentrated in pure form. Gallane is both the simplest member of the gallanes, and the prototype of the monogallanes. It has no economic uses, and is only intentionally produced for academic reasons.
Scandium trihydride is an unstable molecular chemical compound with the chemical formula ScH3. It has been formed as one of a number of other molecular scandium hydride products at low temperature using laser ablation and identified by infrared spectroscopy. Scandium trihydride has recently been the subject of Dirac–Hartree–Fock relativistic calculation studies, which investigate the stabilities, geometries, and relative energies of hydrides of the formula MH3, MH2, or MH.
Binary compounds of hydrogen are binary chemical compounds containing just hydrogen and one other chemical element. By convention all binary hydrogen compounds are called hydrides even when the hydrogen atom in it is not an anion. These hydrogen compounds can be grouped into several types.
Cadmium hydride is an inorganic compound with the chemical formula (CdH
2)
n. It is a solid, known only as a thermally unstable, insoluble white powder.
Indium trihydride is an inorganic compound with the chemical formula. It has been observed in matrix isolation and laser ablation experiments. Gas phase stability has been predicted. The infrared spectrum was obtained in the gas phase by laser ablation of indium in presence of hydrogen gas InH3 is of no practical importance.
Mercury(I) hydride is an inorganic compound with the chemical formula HgH. It has not yet been obtained in bulk, hence its bulk properties remain unknown. However, molecular mercury(I) hydrides with the formulae HgH and Hg
2H
2 have been isolated in solid gas matrices. The molecular hydrides are very unstable toward thermal decomposition. As such the compound is not well characterised, although many of its properties have been calculated via computational chemistry.
Titanium(IV) hydride is an inorganic compound with the empirical chemical formula TiH
4. It has not yet been obtained in bulk, hence its bulk properties remain unknown. However, molecular titanium(IV) hydride has been isolated in solid gas matrices. The molecular form is a colourless gas, and very unstable toward thermal decomposition. As such the compound is not well characterised, although many of its properties have been calculated via computational chemistry.
An iron hydride is a chemical system which contains iron and hydrogen in some associated form.
Mercury(II) hydride is an inorganic compound with the chemical formula HgH
2. It is both thermodynamically and kinetically unstable at ambient temperature, and as such, little is known about its bulk properties. However, it known as a white, crystalline solid, which is kinetically stable at temperatures below −125 °C (−193 °F), which was synthesised for the first time in 1951.
Iron(I) hydride, systematically named iron hydride and poly(hydridoiron) is a solid inorganic compound with the chemical formula (FeH)
n (also written ([FeH])
n or FeH). It is both thermodynamically and kinetically unstable toward decomposition at ambient temperature, and as such, little is known about its bulk properties.
Neodymium(III) hydride is an inorganic compound composed of neodymium and hydrogen with a chemical formula NdH3. In this compound, the neodymium atom is in the +3 oxidation state and the hydrogen atoms are -1. It is highly reactive.
