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The initial investigation of the catalytic activity of DBA dianions was reported by Lorbach et al. [13] Due to the delocalization of these extra electrons in the aromatic system, the DBA dianion is formally isoelectronic with anthracene and should be able to react with dienes in a [4+2] fashion (Diels-Alder reaction). Subjecting the DBA dianion ...
The chromate and dichromate ions are fairly strong oxidizing agents. Commonly three electrons are added to a chromium atom, reducing it to oxidation state +3. In acid solution the aquated Cr 3+ ion is produced. Cr 2 O 2− 7 + 14 H + + 6 e − → 2 Cr 3+ + 7 H 2 O ε 0 = 1.33 V. In alkaline solution chromium(III) hydroxide is produced.
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Furthermore, the dichromate can be protonated: [HCr 2 O 7] − ⇌ [Cr 2 O 7] 2− + H +, pK a = 1.8 [6] Loss of the second proton occurs in the pH range 4–8, making the ion [HCrO 4] − a weak acid. [citation needed] Molecular chromic acid could in principle be made by adding chromium trioxide to water (cf. manufacture of sulfuric acid). CrO ...
A dianion is an anion with a net charge of −2. While there exist many stable molecular dianions, such as BeF 4 2− and MgF 4 2− , [ 1 ] thus far no stable atomic dianion has been found: Electron shielding and other quantum mechanical effects tend to make the addition of another electron to an atomic anion unstable.
One family of reagents employs the complex CrO 3 (pyridine) 2. [2] Sarett's reagent: a solution of CrO 3 (pyridine) 2 in pyridine. It was popularized for selective oxidation of primary and secondary alcohols to carbonyl compounds. Collins reagent is a solution of the same CrO 3 (pyridine) 2 but in dichloromethane. The Ratcliffe variant of ...
Diborane(4) is a transient inorganic compound with the chemical formula B 2 H 4.Stable derivatives are known. Diborane(4) has been produced by abstraction of two hydrogen atoms from diborane(6) using atomic fluorine and detected by photoionization mass spectrometry. [1]
Potassium chlorochromate was originally prepared by treating potassium dichromate with hydrochloric acid. An improved route involves the reaction of chromyl chloride and potassium chromate: [5] K 2 CrO 4 + CrO 2 Cl 2 → 2KCrO 3 Cl. The salt consists of the tetrahedral chlorochromate anion. The average Cr=O bond length is 159 pm, and the Cr-Cl ...