Thallium selenocyanates

Ramakrishna and Thuraisingham [73RAM/THU] studied the complex formation between Tl and SeCN at 300 K in 2 M NaNO. medium by polarographic measurements. The evaluation of the E a vs. [SeCN ] data relied on graphical techniques and indicated the formation of three mononuclear complexes  

The uncertainty limits include an assumed uncertainty in the original value of 

Combined with the value for Af (SeCN 298.15 K) selected in this review, and the [99RAR/RAN] value of AfC°(Tr, 298.15 K) (-32.40 kJ mol ), this corresponds to  

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The pseudohalides and related compounds have been investigated by a number of workers. Thallium(I) cyanate and thiocyanate are both known, and the latter has been shown to be ionic in the solid state 288 differing values have been reported for the stability constants in the T1/NCS system in aqueous or mixed water/non-aqueous systems, but the overall evidence is that the complexes are extremely weak.289 The ionic selenocyanate has been reported, but the chemistry has not been investigated.1... 

Thallium(I) forms salts with cyanide (CN ), cyanamide (NCN ), azide (Ns"), cyanate (OCN ), isocyanate (CNO"), thiocyanate (SCN"), and selenocyanate (SeCN ) however, complexes with these hgands, hke the Tl -halide complexes, are very weak. In contrast, the neutral Tl Xs species are not well known, although the Tl -pseudohahde complexes are more or less stable. 

RAM/THU] Ramakrishna, R. S., Thuraisingham, R., Polarographic studies of the thiocyanates and selenocyanates of thallium, indium and gallium, J. Inorg. Nucl. Chem., 35, (1973), 2805-2812. Cited on page 254. 

With other halides, the reaction is conveniently performed by treatment of the alkylthdlium compound with the appropriate copper(I) halide. The product yield is increased by the addition of potassium halide.jhe thallium moiety can also be replaced by other groups, similarly to the arylthallium compounds. The cyano group is introduced by reaction with copper(I) cyanide.lSi the thiocyano group by reaction with potassium and/or copper thiocyanate>5i.i52 and the selenocyano group by treatment with potassium selenocyanate. 

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