Thiocyanate mixed-ligand

The coordination chemistry of the cyanate, thiocyanate and selenocyanate ligands has been recently reviewed.1874 Platinum(II) forms the complex ion Pt(SCN)2-, and the corresponding homoleptic platinum(IV) complex Pt(SCN)i can be prepared. Numerous mixed ligand complexes of platinum(II) are known containing the thiocyanate ligand and other ligands, although there are fewer platinum(IV) examples. 4... 

We have noted that N-bonded thiocyanate complexes dissociate readily in solution. Mixed ligand complexes of lanthanides with thiocyanates and L = ethanol, pyridine, triphenyl phosphorous oxide, phenanthroline, etc. have been synthesized. 

Infrared and electronic spectra confirm the nature of the hexa-N-thiocyanatometallate anions of chromium(III) (293, 639, 647, 656, 663, 665) and molybdenum(III) (293, 489, 647, 663, 664), and molyb-denum(II) (534) a variety of salts have been reported containing these anions (see the foregoing and also Refs. 30 and 528). Infrared spectra and magnetic measurements have been used to characterize [M(NCS)e] (M = Mo, W) and [W(NCS)g] (386). A large number of mixed-ligand thiocyanate complexes of chromium(III) have been reported, and many of these are of the type M[Cr(CNS)4L2], similar to the original Reinecke s salt where L = NH3. 

Some Mixed-Ligand Complexes with Iron Thiocyanate... 

Some Mixed-Ligand Complex Thiocyanates or Palladium(II) and Platinum(II)... 

Mixed-ligand platinum(II) thiocyanates are quite numerous and many have been included in Table XXXII with some similar palladium-(II) compounds. Linkage isomerism has been observed in solution for... 

Much of the work on mixed-ligand complexes containing the thiocyanate group stems from the discovery by Turco and Pecile in 1961... 

Nature of Cooperative Effects in Mixed-Ligand Thiocyanate Complexes Various explanations have been put forward to account for the effects of neutral ligands on the nature of the metal-thiocyanate bond TT-bonding, symbiosis, and antisymbiosis of hard and soft acids and bases as well as steric effects have all been discussed. In addition, directional... 

In an indirect method, thiocyanate and Hg(II) form a mixed-ligand mercury complex with quinoline, which can be extracted into chloroform. This complex can be treated with a CHCI3 solution of dithizone to form the Hg(HDz)2 complex [45]. 

Thiocyanate extractions are therefore often performed in 0.5 M IT Cl, i.e., at a pH of 0.3. Furthermore, the acid used to enforce such a low pH may introduce competing ligands, such as Cl . In that case, we must also consider the acid-base equilibrium of thiocyanate (HSCN has a pKa of 0.9) and the possibility of the formation of neutral ferric complexes of mixed ligand composition. 

Formation constants of 3d metal ions with A-m-tolyl-p-substituted benzohydroxamic acids and of rare earths with thenoylhydroxamic acid have been determined. Formation constants of proton and metal complexes of iV-phenyl-2-thenoyl- and A-p-tolyl-2-thenoyl-hydroxamic acids have also been determined. In addition, study has been made of the mixed ligand complexes involving nicotine- and isonicotino-hydroxamic acids. A method of extraction and spectrophotometric determination of vanadium with chlorophenylmethylbenzohydroxamic acid has also been published. It may be mentioned that hydroxamic acids (in particular, the A-phenylbenzohydroxamic acid) have been widely used as analytical reagents for metal ions. Solvent extraction of titanium by benzo- or salicyl-hydroxamic acid in the presence of trioctylamine in the form of coloured complexes has been reported. A-w-Tolyl-p-methoxybenzohydroxamic acid has been used for extraction and spectrophotometric determination of Mo and W from hydrochloric acid media containing thiocyanate. 

Here added ammonia or thiocyanate inhibit reaction by forming mixed ligand chelates of some stability. 

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