Selenium oxychloride complexes

Condensation between phenol and selenium oxychloride in ether or chloroform solution produces two isomeric selenonium chlorides, [(HO.CeH4)3Se]Cl, each containing chlorine precipitable as silver chloride and replaceable by other acid radicals. The three phenolic hydroxyl groups of the complex cation impart acidic properties to the chlorides, causing them to be soluble in aqueous caustic alkali. From such solutions carbonic or acetic acid precipitates the amphoteric oxide [(H0.C6H4)8Se]20, which redissolves in alkalis and reacts with acids to give a bromide, nitrate, sulphate and chloroplatinate. The following scheme shows the compounds obtained ... 

Similar solvent properties are exhibited by acetyl- or benzoyl chloride " as solvents, while phosphorus oxychloride , phenylphosphonic dichloride and selenium oxychloride have somewhat higher donor numbers. They are still useful for the preparation of various complex chlorides, in particular selenium oxychloride, which has also a reasonable dielectric constant. Ionic compounds such as potassium chloride can be dissolved with the rapid formation of chloro-complexes ... 

In the oxyhalides discussed so far the donor properties at the 0-atoms are too small to be considered in connection with the formation of anionic complexes and their capacities for solute-dissolution are poor. Solvents of higher donor number allow a wider range of solubilities, since more energy is provided by the interactions with acceptors, such as metal ions. Selenium oxychloride , phosphorus oxychloride and phenylphosphonic dichloride are much better donor-solvents than the oxyhalides discussed above. Coordination chemistry in their solutions may be explained in terms of competing reactions between the donor solvent molecules and the competitive ligands towards the acceptor molecules or acceptor ions ... 

Thionyl chloride, as well as other inorganic acid chlorides, reacts with polyols to form mixed esters (see under Sulfate esters. Chapter III). In the presence of pyridine, partial chlorohydrin formation may occur (95), Selenium oxychloride forms a selenite ester upon reaction with mannitol (96), Phosphorus pentachloride yields unsaturated chlorohydrins of mannitol and galactitol which have the composition CeHeCU (97), Extremely interesting are the so-called complexes of alditols with various inorganic polybasic acids, their salts, or anhydrides in aqueous solutions. Complexes with boric, molybdic, tungstic, and other acids, as well as the oxides of antimony and arsenic, have been reported. It is believed that these complexes are true esters with one or more moles of alditol, a chelate type of structure being involved at some point. For the hexitols a compound with boric acid such as the following is postulated (98),... 

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