Cadmium thiocyanates

Mass effects due to some ions in salts. It is generally observed that there is a greater instability amongst compounds containing heavy atoms compared with elements in the first periods of the periodic tabie.This can be observed by analysing enthalpies of formation of ammonia, phosphine, arsine and stibine (see previous table for the last three). In the same way, it is easier to handle sodium azide than lead azide, which is a primary explosive for detonators. It is exactly the same with the relatively highly stable zinc and cadmium thiocyanates and the much less stable mercury thiocyanate. 

Cadmium thiocyanates, 17 333-336 Cadmium trifluoroacetates, 17 25, 26 CAD spectra, see Collisionally activated dissociation spectra... 

Cadmium arsenide, nitride, selenide. and telluride are known, the first and third ohlainahle front the elements, while the nitride is obtained by heating the amide lubtained by reaction of cadmium thiocyanate and potassium amide in liquid NHi). and (lie telluride is obtainable by reduction ol the lcllurate with hydrogen. Cadmium arsenide is used as a seiniconducinr. 

White Cd(CN)2 is sparingly soluble in water, except in the presence of CN ions, owing to the formation of soluble anionic complexes. On heating it darkens and decomposes at about 200 °C. Cd(CN)2, like Zn(CN)2, has a cubic anti-cuprite structure. Colorless cadmium thiocyanate is sparingly soluble in water, ethanol, and liquid ammonia. In the solid, Cd + is surrounded by an N2S4 octahedron. Cadmium thiocyanate polymers exhibit highly anisotropic physical properties. Yellow Cd(N3)2 is prepared by mixing solutions of Cd(N03)2 and NaNs. The crystals are orthorhombic and decompose with detonation when heated. Cadmium pseudohalides (see Pseudohalide) may be prepared by metathesis (equation 3). 

Table A-119 Stability constants of cadmium thiocyanate complexes (mean values) in NaC104 medium with an extrapolation to / = 0 by the SIT method. The uncertainties correspond to twice the standard deviation from the least-squares calculation.

Table A-119 Stability constants of cadmium thiocyanate complexes (mean values) in NaC104 medium...

Cadmium thiocyanate (7 g.) is placed on filter disk b of vessel a (Fig. 283). About 15 ml. of carefully purified NH3 is condensed... 

Figure 9.21. Dependence of stability constants for cadmium thiocyanate complexes on 1/e in mixed solvent water-methanol at 298.15K.

CgH2ftBr2N12NiSg, Hexakis(thiourea)nickel(II) bromide, 34B, 523 C8Hi2CdN6Sn, Bis(ethylenethiourea)cadmium thiocyanate, 24, 536 C8H,gCdN12S8Zn, Tetrakisthioureacadmium tetraisothiocyanatozincate, 32A, 240 32B, 409... 

Although cadmium sulfide exists in two crystalline forms (hexagonal or greenockite type, and cubic or hawleyite type, qq.v.), an amorphous form may also be synthesised. This phase can reportedly coexist with the other crystalline forms at room temperature. According to Budgen (1924), amorphous cadmium sulfide may be formed either by the adding cadmium oxide to molten potassium thiocyanate, or by heating cadmium thiocyanate with acetic acid in a sealed tube at 250 C. 

Budesmsky proposed a method based on the quantitative reaction of isoniazid with cadmium thiocyanate at pH 6 to 7 to give the complex [CdCCeH ONs)] (SCN). ... 

Dissolve 01 to 0 5 g in 15 ml of water, add 20 ml of 0-25M cadmium thiocyanate and dilute to volume with water. Mix well, filter and titrate the excess thiocyanate in 10 ml of the filtrate. 1 ml 0-25M cadmium thiocyanate = 0 03429 g C6H7ON3. 

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