Tellurium, Te Hydrogen, H | |
Names | |
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IUPAC name Hydrogen ditelluride | |
Systematic IUPAC name Ditellane | |
Other names ditellane Dihydrogen ditellanide | |
Identifiers | |
3D model (JSmol) | |
ChEBI | |
ChemSpider | |
239518 | |
PubChem CID | |
CompTox Dashboard (EPA) | |
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Properties | |
H2Te2 | |
Molar mass | 257.22 g·mol−1 |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). |
Hydrogen ditelluride or ditellane is an unstable hydrogen dichalcogenide containing two tellurium atoms per molecule, with structure H−Te−Te−H or (TeH)2. Hydrogen ditelluride is interesting to theorists because its molecule is simple yet asymmetric (with no centre of symmetry) and is predicted to be one of the easiest to detect parity violation, in which the left handed molecule has differing properties to the right handed one due to the effects of the weak force.
Hydrogen ditelluride can possibly be formed at the tellurium cathode in electrolysis in acid. [2] When electrolysed in alkaline solutions, a tellurium cathode produces ditelluride Te2−2 ions, as well as Te2− and a red polytelluride. The greatest amount of ditelluride is made when pH is over 12. [3]
Apart from its speculative detection in electrolysis, ditellane has been detected in the gas phase produced from di-sec-butylditellane. [1] [4]
Hydrogen ditelluride has been investigated theoretically, with various properties predicted. The molecule is twisted with a C2 symmetry. There are two enantiomers. Hydrogen ditelluride is one of the simplest possible unsymmetrical molecules; any simpler molecule will not have the required low symmetry. The equilibrium geometry (not counting zero point energy or vibrational energy) has bond lengths of 2.879 Å between the tellurium atoms and 1.678 Å between hydrogen and tellurium. The H−Te−Te angle is 94.93°. The angle of lowest energy between the two H−Te bonds (the dihedral angle between the Ha−Te−Te and Te−Te−Hb planes) is 89.32°. The trans configuration is higher in energy (3.71 kcal/mol), and the cis would be even higher (4.69 kcal/mol). [5]
Being chiral, the molecule is predicted to show evidence of parity violation, though this may get interference from stereomutation tunneling, where the P enantiomer and M enantiomer spontaneously convert into each other by quantum tunneling. The parity violation effect on energy comes about from virtual Z boson exchanges between the nucleus and electrons. [6] It is proportional to the cube of the atomic number, so is stronger in tellurium molecules than others higher up in the periodic table (O, S, Se). Because of parity violation, the energy of the two enantiomers differs, and is likely to be higher in this molecule than most molecules, so an effort is underway to observe this so-far undetected effect. The tunneling effect is reduced by higher masses, so that the deuterium form, D2Te2 will show less tunneling. In a torsional vibrational mode, the molecule can twist back and forward storing energy. Seven different quantum vibration levels are predicted below the energy to jump to the other enantiomer. The levels are numbered vt = 0 up to 6. The sixth level is predicted to be split into two energy levels because of quantum tunneling. [7] The parity violation energy is calculated as 3×10−9 cm−1 or 90 Hz. [7]
The different vibrational modes for H2Te are symmetrical stretch of H−Te, symmetrical bend of H−Te−Te, torsion, stretch Te−Te, asymmetrical stretch H−Te, asymmetrical bend of H−Te−Te. [7] The time to tunnel between enantiomers is only 0.6 ms for 1H2Te2, but is 66000 seconds (18 h 20 min) for the tritium isotopomer T2Te2. [7]
There are organic derivatives, in which the hydrogen is replaced by organic groups. One example is bis(2,4,6-tributylphenyl)ditellane. [8] Others are diphenyl ditelluride and 1,2-bis(cyclohexylmethyl)ditellane. A ligand -TeTeH is known in some transition metal complexes. IUPAC nomenclature calls this "ditellanido".
In chemistry, a structural isomer of a compound is another compound whose molecule has the same number of atoms of each element, but with logically distinct bonds between them. The term metamer was formerly used for the same concept.
Tellurium is a chemical element; it has symbol Te and atomic number 52. It is a brittle, mildly toxic, rare, silver-white metalloid. Tellurium is chemically related to selenium and sulfur, all three of which are chalcogens. It is occasionally found in its native form as elemental crystals. Tellurium is far more common in the Universe as a whole than on Earth. Its extreme rarity in the Earth's crust, comparable to that of platinum, is due partly to its formation of a volatile hydride that caused tellurium to be lost to space as a gas during the hot nebular formation of Earth.
In chemistry and manufacturing, electrolysis is a technique that uses direct electric current (DC) to drive an otherwise non-spontaneous chemical reaction. Electrolysis is commercially important as a stage in the separation of elements from naturally occurring sources such as ores using an electrolytic cell. The voltage that is needed for electrolysis to occur is called the decomposition potential. The word "lysis" means to separate or break, so in terms, electrolysis would mean "breakdown via electricity."
A timeline of atomic and subatomic physics.
In chemistry, an enantiomer – also called optical isomer, antipode, or optical antipode – is one of two stereoisomers that are nonsuperposable onto their own mirror image. Enantiomers of each other are much like one's right and left hands; without mirroring one of them, hands cannot be superposed onto each other. It is solely a relationship of chirality and the permanent three-dimensional relationships among molecules or other chemical structures: no amount of re-orientiation of a molecule as a whole or conformational change converts one chemical into its enantiomer. Chemical structures with chirality rotate plane-polarized light. A mixture of equal amounts of each enantiomer, a racemic mixture or a racemate, does not rotate light.
Asymmetry is the absence of, or a violation of, symmetry. Symmetry is an important property of both physical and abstract systems and it may be displayed in precise terms or in more aesthetic terms. The absence of or violation of symmetry that are either expected or desired can have important consequences for a system.
Molecular physics is the study of the physical properties of molecules and molecular dynamics. The field overlaps significantly with physical chemistry, chemical physics, and quantum chemistry. It is often considered as a sub-field of atomic, molecular, and optical physics. Research groups studying molecular physics are typically designated as one of these other fields. Molecular physics addresses phenomena due to both molecular structure and individual atomic processes within molecules. Like atomic physics, it relies on a combination of classical and quantum mechanics to describe interactions between electromagnetic radiation and matter. Experiments in the field often rely heavily on techniques borrowed from atomic physics, such as spectroscopy and scattering.
In physical organic chemistry, a kinetic isotope effect (KIE) is the change in the reaction rate of a chemical reaction when one of the atoms in the reactants is replaced by one of its isotopes. Formally, it is the ratio of rate constants for the reactions involving the light (kL) and the heavy (kH) isotopically substituted reactants (isotopologues):
In physics, a parity transformation is the flip in the sign of one spatial coordinate. In three dimensions, it can also refer to the simultaneous flip in the sign of all three spatial coordinates :
In physics and chemistry, a selection rule, or transition rule, formally constrains the possible transitions of a system from one quantum state to another. Selection rules have been derived for electromagnetic transitions in molecules, in atoms, in atomic nuclei, and so on. The selection rules may differ according to the technique used to observe the transition. The selection rule also plays a role in chemical reactions, where some are formally spin-forbidden reactions, that is, reactions where the spin state changes at least once from reactants to products.
Homochirality is a uniformity of chirality, or handedness. Objects are chiral when they cannot be superposed on their mirror images. For example, the left and right hands of a human are approximately mirror images of each other but are not their own mirror images, so they are chiral. In biology, 19 of the 20 natural amino acids are homochiral, being L-chiral (left-handed), while sugars are D-chiral (right-handed). Homochirality can also refer to enantiopure substances in which all the constituents are the same enantiomer, but some sources discourage this use of the term.
Sodium tellurite is an inorganic tellurium compound with formula Na2TeO3. It is a water-soluble white solid and a weak reducing agent. Sodium tellurite is an intermediate in the extraction of the element, tellurium; it is a product obtained from anode slimes and is a precursor to tellurium.
In organic chemistry, a ring flip is the interconversion of cyclic conformers that have equivalent ring shapes that results in the exchange of nonequivalent substituent positions. The overall process generally takes place over several steps, involving coupled rotations about several of the molecule's single bonds, in conjunction with minor deformations of bond angles. Most commonly, the term is used to refer to the interconversion of the two chair conformers of cyclohexane derivatives, which is specifically referred to as a chair flip, although other cycloalkanes and inorganic rings undergo similar processes.
In chemistry, molecular symmetry describes the symmetry present in molecules and the classification of these molecules according to their symmetry. Molecular symmetry is a fundamental concept in chemistry, as it can be used to predict or explain many of a molecule's chemical properties, such as whether or not it has a dipole moment, as well as its allowed spectroscopic transitions. To do this it is necessary to use group theory. This involves classifying the states of the molecule using the irreducible representations from the character table of the symmetry group of the molecule. Symmetry is useful in the study of molecular orbitals, with applications to the Hückel method, to ligand field theory, and to the Woodward-Hoffmann rules. Many university level textbooks on physical chemistry, quantum chemistry, spectroscopy and inorganic chemistry discuss symmetry. Another framework on a larger scale is the use of crystal systems to describe crystallographic symmetry in bulk materials.
In chemistry, isomers are molecules or polyatomic ions with identical molecular formula – that is, same number of atoms of each element – but distinct arrangements of atoms in space. Diamond and graphite are a familiar example; they are isomers of carbon. Isomerism refers to the existence or possibility of isomers.
Triatomic hydrogen or H3 is an unstable triatomic molecule containing only hydrogen. Since this molecule contains only three atoms of hydrogen it is the simplest triatomic molecule and it is relatively simple to numerically solve the quantum mechanics description of the particles. Being unstable the molecule breaks up in under a millionth of a second. Its fleeting lifetime makes it rare, but it is quite commonly formed and destroyed in the universe thanks to the commonness of the trihydrogen cation. The infrared spectrum of H3 due to vibration and rotation is very similar to that of the ion, H+
3. In the early universe this ability to emit infrared light allowed the primordial hydrogen and helium gas to cool down so as to form stars.
Tellurols are analogues of alcohols and phenols where tellurium replaces oxygen. Tellurols, selenols, and thiols have similar properties, but tellurols are the least stable. Although they are fundamental representatives of organotellurium compounds, tellurols are lightly studied because of their instability. Tellurol derivatives include telluroesters and tellurocyanates (RTeCN).
In chemistry, ethanium or protonated ethane is a highly reactive positive ion with formula C
2H+
7. It can be described as a molecule of ethane with one extra proton, that gives it a +1 electric charge.
Molybdenum(IV) telluride, molybdenum ditelluride or just molybdenum telluride is a compound of molybdenum and tellurium with formula MoTe2, corresponding to a mass percentage of 27.32% molybdenum and 72.68% tellurium.
Martin Quack is a German physical chemist and spectroscopist; he is a professor at ETH Zürich.