Organogermanium chemistry is the science of chemical species containing one or more C–Ge bonds. Germanium shares group 14 in the periodic table with carbon, silicon, tin and lead. Historically, organogermanes are considered as nucleophiles and the reactivity of them is between that of organosilicon and organotin compounds. Some organogermanes have enhanced reactivity compared with their organosilicon and organoboron analogues in some cross-coupling reactions.
The great majority of organogermanium compounds are tetrahedral with the formula GeR4-nXn where X = H, Cl, etc. Ge-C bonds are air-stable, although Ge-H bonds can undergo air-oxidation. The first organogermanium compound, tetraethylgermane, synthesized by Winkler in 1887, by the reaction of germanium tetrachloride with diethylzinc. More commonly, these Ge(IV) compounds are prepared by alkylation of germanium halides by organolithium and Grignard reagents. The method has been applied to surfaces terminated with Ge-Cl bonds.
Some organogermanes are prepared by nucleophilic substitution or Pd-catalyzed cross-coupling reactions. Hydrogermylation provides another route to organogermanium compounds.
Akin to hydrocarbons and polysilanes, many organogermanium compounds are known with Ge-Ge bonds. An early example is hexaphenyldigermane, . It is prepared by Wurtz coupling of the bromide:
Many cyclic polygermanes are known, e.g. .
Triphenylgermanol ((C6H5)3GeOH) is a colorless solid. Like the isostructural silanol, it engages in hydrogen bonding in the solid-state.
Compounds with multiple bonds to Ge are usually highly reactive or require bulky organic substituents for their isolation. This situation follows from the double bond rule. Digermynes only exist for extremely bulky substituents. According to X-ray crystallography, the C–Ge≡Ge–C core of digermynes is bent. Such compounds are prepared by the reduction of bulky arylgermanium(II) halides.
Compounds containing Ge=C (germenes) double bonds require bulky organic substituents for their isolation.
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Organotin chemistry is the scientific study of the synthesis and properties of organotin compounds or stannanes, which are organometallic compounds containing tin carbon bonds. The first organotin compound was diethyltin diiodide (), discovered by Edward Frankland in 1849. The area grew rapidly in the 1900s, especially after the discovery of the Grignard reagents, which are useful for producing Sn–C bonds. The area remains rich with many applications in industry and continuing activity in the research laboratory.
The carbon group is a periodic table group consisting of carbon (C), silicon (Si), germanium (Ge), tin (Sn), lead (Pb), and flerovium (Fl). It lies within the p-block. In modern IUPAC notation, it is called group 14. In the field of semiconductor physics, it is still universally called group IV. The group is also known as the tetrels (from the Greek word tetra, which means four), stemming from the Roman numeral IV in the group names, or (not coincidentally) from the fact that these elements have four valence electrons (see below).
In chemistry, a lone pair refers to a pair of valence electrons that are not shared with another atom in a covalent bond and is sometimes called an unshared pair or non-bonding pair. Lone pairs are found in the outermost electron shell of atoms. They can be identified by using a Lewis structure. Electron pairs are therefore considered lone pairs if two electrons are paired but are not used in chemical bonding. Thus, the number of electrons in lone pairs plus the number of electrons in bonds equals the number of valence electrons around an atom.
Treatment of potassium salts of silole dianions with donor stabilised germanium dichlorides gave the anticipated silagermafulvenylidenes R2Si = Ge(Do) (R2Si = 1-silacyclopentadiendiyl, Do = N-heterocyclic carbene (NHC)) only as transient intermediates in a ...
Bi-stable charge-neutral iron(II) spin-crossover (SCO) complexes are a class of switchable molecular materials proposed for molecule-based switching and memory applications. In this study, we report on the SCO behavior of a series of iron(II) complexes com ...
2020
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The reorganization energy (lambda), which quantifies the structural rearrangement of a molecule when accommodating a charge, is a key parameter in the evaluation of charge mobility in molecular solids. However, it is unclear how lambda is influenced by con ...