Ó Sé

Ó Sé may refer to:

Tomás Ó Sé, Irish sportsman

Marc Ó Sé, Irish sportsman

Páidí Ó Sé (1955-2012), Irish footballer

Darragh Ó Sé, Irish sportsman

Dáithí Ó Sé, Irish television personality

Mícheál Ó Sé, Irish sportsman

Selenium trioxide

Selenium trioxide is the inorganic compound with the formula Se O₃. It is white, hygroscopic solid. It is also an oxidizing agent and a Lewis acid. It is of academic interest as a precursor to Se(VI) compounds.

Preparation

Selenium trioxide is difficult to prepare because it is unstable with respect to the dioxide:

It has been generated in a number of ways despite the fact that the dioxide does not combust under normal conditions.One method entails dehydration of anhydrous selenic acid with phosphorus pentoxide at 150-160 °C. The reaction of liquid sulfur trioxide with potassium selenate

Reactions

In its chemistry SeO₃ generally resembles sulfur trioxide, SO₃, rather than tellurium trioxide, TeO₃.

At 120 °C SeO₃ reacts with selenium dioxide to form the Se(VI)-Se(IV) compound diselenium pentoxide:

It reacts with selenium tetrafluoride to form selenoyl fluoride, the selenium analogue of sulfuryl fluoride

As with SO₃ adducts are formed with Lewis bases such as pyridine, dioxane and ether.

This page contains text from Wikipedia, the Free Encyclopedia - https://wn.com/Selenium_trioxide

Selenium dioxide

Selenium dioxide is the chemical compound with the formula SeO₂. This colorless solid is one of the most frequently encountered compounds of selenium.

Properties

Solid SeO₂ is a one-dimensional polymer, the chain consisting of alternating selenium and oxygen atoms. Each Se atom is pyramidal and bears a terminal oxide group. The bridging Se-O bond lengths are 179 pm and the terminal Se-O distance is 162 pm. The relative stereochemistry at Se alternates along the polymer chain (syndiotactic). In the gas phase selenium dioxide is present as dimers and other oligomeric species, at higher temperatures it is monomeric. The monomeric form adopts a bent structure very similar to that of sulfur dioxide with a bond length of 161 pm. The dimeric form has been isolated in a low temperature argon matrix and vibrational spectra indicate that it has a centrosymmetric chair form. Dissolution of SeO₂ in selenium oxydichloride give the trimer [Se(O)O]₃. Monomeric SeO₂ is a polar molecule, with the dipole moment of 2.62 D pointed from the midpoint of the two oxygen atoms to the selenium atom.