Triphenylantimony oxidation

Several phosphorous compounds having a P=S bond are also catalysts for this reaction. For example, heating of phenyl isocyanate with triphenylphosphine sulfide at 160 °C affords diphenylcarbodiimide. Since triphenylphosphine sulfide was recovered unchanged, a different mechanism seems to be operative. A tricyclic P S compound, S=P[N(Me)CH2CH2l3N, also catalyzes the transformation of isocyanates to carbodiimides. Triphenylarsine oxide and triphenylantimony oxide also catalyze the conversion of isocyanates into carbodiimides. The catalytic activity of the oxides of phosphorous, arsenic and antimony are in agreement with the dipole moments of... 

These oxidation reactions are performed under neutral conditions at ambient temperature, contrary to similar oxidations with organylantimony oxides which often need more severe conditions. The findings clearly show the difference in chemical behavior between bismuthine oxides and other orga-nylpnicogen oxides. It is likely that the chemical nature of organylbismuthine oxides depends considerably on its preparative procedures. For some time now, a similar phenomenon has been noticed with triphenylantimony oxide that exists in a dimeric, oligomeric or polymeric form. 

Stevani and Baader attempted, unsuccessfully, to trap the volatile intermediate with triphenylantimony. Unfortunately, poly(triphenylstibine) oxide was formed instead of the expected insertion product, 2,2,2-triphenyl-2k -l,3,2-dioxastibolane-4,5-dione, probably by the reaction of triphenylantimony with hydrogen peroxide, carried by the gas stream to the flask containing triphenylantimony. Although it was impossible to detect the trapping product of 1,2-dioxetanedione by triphenylantimony, that does not necessarily mean that this substance is not formed during the reaction. This intermediate might... 

Reduction of the radical cation of bis(dithiazole) 23a with triphenylantimony affords the neutral heterocycle 23 < 1997JA12136>. Oxidation of compound 23 to radical cation 23a can be effected by heating a chlorobenzene solution with an excess of sulfur dichloride. Further oxidation of 23a with PhICl2 or SOCl2 in the presence of AICI3 in liquid S02 gives the closed shell dicationic salt 23b (Scheme 14). 

How can we assess the thermochemical data presented in Table 1 Many were obtained by static-bomb calorimetry. Regrettably, this technique is clearly unsuitable to deal with these substances due to the ill-defined composition of the combustion products (see the discussion in References 13 and 28). The formation of nonstoichiometric oxides upon combustion all but precludes the experimental rigor demanded of the combustion calorimetrist. This fact, by itself, allows us to question the reliability of the values shown for all of the trialkyl compounds and for triphenylantimony. Although the results for triphenylbismuth found by static and rotating-bomb calorimetry overlap within their error bars, this has been suggested to be fortuitous ... 

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