Thiocyanation and selenocyanation

Thiocyanates and selenocyanates can be made by fusing the corresponding cyanide with S or Se. The SCN and SeCN ions are both linear, like OCN . (See p, 779 for TeCN ) Treatment of KSCN with dry KHSO4 produces free isothiocyanic acid HNCS, a white crystalline solid which is stable below 0° but which decomposes rapidly at room temperatures to HCN and a yellow solid H2C2N2S3. Thiocyanic acid, HSCN, (like HOCN) has not been prepared... 

Coordination chemistry of cyanate, thiocyanate and selenocyanate ions. A. H. Norbury, Adv. Inorg. Chem. Radiochem., 1975,17,232-386 (825). 

Coordination Chemistry of the Cyanate, Thiocyanate, and Selenocyanate Ions A. H. Norbury... 

In recent years research in the field of transition-metal thiocyanates and selenocyanates received a new impetus, because of the partly interesting physical properties of such crystalline species. A review on Cd and Hg thiocyanate systems collects and sorts results of this endeavor.371 The nonlinear optical (NLO) properties of Cd thiocyanate and selenocyanate systems and criteria for the design of NLO crystals (crystal engineering), especially, have been discussed afterwards.372 Further contributions to the field have also been described.37, 374 The structure of mercury chlorothiocyanate has been re-determined.375... 

Therefore, if an acceptor coordinates thiocyanate and selenocyanate ions via their S and Se donor atoms, respectively, the selenocyanate complexes should be considerably stronger than the thiocyanate complexes, and moreover formed in considerably more exothermic reactions. If, on the other hand, an acceptor prefers to coordinate these ligands via their harder donor atom N, the bonds formed will be less covalent and the reactions much less exothermic than in the case of S or Se coordination. The strength of the bonds will be little influenced by an exchange of S for Se and much the same value of AH°n may therefore be expected for thiocyanate and selenocyanate complexes. 

Further papers in this section include the hydrosilylation of a-pinene and of j8-pinene, ° thiocyanation and selenocyanation of a-pinene, ° cationic polymerization of a- and /3-pinene epoxides,bromination of ( )-c/s-pinonic acid with dioxan dibromide, and straightforward myrtenol (224 R=CH20H) ° and tetrahydroperillyl alcohol syntheses from -pinene epoxide. 

The group VIB cyanides, thiocyanates and selenocyanates and their complexes with species such as thiourea have been described.1,45 For example, the tellurium dithiocyanate complex has been prepared45 by treatment of tellurium dichloride or tellurium dibromide with ammonium thiocyanate. It seems that little information exists on the preparation of tellurocyanates and there is a sparsity of data on polonium derivatives. Indeed, the only known cyanide of polonium is probably a salt of the quadrivalent element.1... 

Zirconium and hafnium cyanate, thiocyanate, and selenocyanate complexes that contain N-heterocyclic ligands are discussed in Sections 32.4.2.5.iii, 32.4.2.5.iv and 32.4.2.5.V. 

Mercuric Selenocyanate, Hg(CNSe)a, forms a crystalline mass when mercuric acetate is treated with potassium selenocyanate. The crystalline mass consists of white needles which are slightly soluble in cold water but readily soluble in alkali cyanide, thiocyanate and selenocyanate solutions. Mercuric selenocyanate turns brown in air and is decomposed by heat.4... 

Organomercury thiocyanates and selenocyanates HgNCXL react with Ni(NCS)2L4 (L = py, 4-aminopyridine, aniline) affording complexes having the stoichiometry Hg2Ni(NCX)4-L2L2 1 91 1093... 

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... 

Complexes with pyridine JV-oxide of zinc thiocyanate and selenocyanate of the stoichiometry ZnLsX2 (X = SCN, SeCN) have been reported.1066 IR evidence shows that they are best formulated as [ZnL6]2+[ZnX4f. ... 

Tabic 1 Typical Palladium(II)-Thiocyanate and -Selenocyanate Complexes and IR Data ... 

These results explain previous observations of the greater stability of zirconium thiocyanate and selenocyanate complexes compared with their hafnium analogues, and the greater stability of zirconium and hafnium complexes in MeCN compared with DMF in terms of competition between the ligand and solvent molecules for co-ordination sites on the metal. Zirconium alkoxides have been prepared from ZrCl4 and aliphatic alcohols158 but with salicylaldehyde a Meerwein-Ponndorf... 

Thiocyanate groups can be linked to tellurium via the nitrogen or sulfur atoms. In view of this uncertainty, cyanates, thiocyanates, and selenocyanates are discussed together under diorgano dinitrogen compounds (p. 637). 

Cyanatc, thiocyanate, and selenocyanate groups can be linked to tellurium via the chalcogen atom or via the nitrogen atom. The v(C—X) infrared absorption bands have been used to distinguish between these two bonding modes. The iso (N-bonded) organic cyanates, R-NCX, have v(C-X) at higher wave numbers than the normal (X-bonded) compounds, R-XCN. 

Lanthanide complexes of 1,10-phenanthroline (phen) have been obtained as chlorides, nitrates, sulfates, perchlorates acetates, thiocyanates and selenocyanates from various solvents. 

Table 12 Anionic Species with Cyanate, Thiocyanate and Selenocyanate...

The thiocyanate and selenocyanate ions (SCN- and SeCN-) react with RhCl3 3H20 to form [RhXfi]3" anions.1170"1172 Both the SCN- and the SeCN- are chalcogen-bonded, consistent with the soft character of the Rh111 in many complexes. 

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