Trans thiocyanate

When the mother liquor, without the washings, is treated with 6.8g more of KSCN, the trans thiocyanate precipitates out this is washed first with 50% aqueous alcohol, and then with 95% solvent. 

Ni(CisH28N2S2)(NCS)2] 32 ) room 3.10 Gouy, Farad trans-thiocyanate complex six-coordination suggested 73U8... 

The majority of U(V1) coordination chemistry has been explored with the trans-ddo s.o uranyl cation, UO " 2- The simplest complexes are ammonia adducts, of importance because of the ease of their synthesis and their versatihty as starting materials for other complexes. In addition to ammonia, many of the ligand types mentioned ia the iatroduction have been complexed with U(V1) and usually have coordination numbers of either 6 or 8. As a result of these coordination environments a majority of the complexes have an octahedral or hexagonal bipyramidal coordination environment. Examples iuclude U02X2L (X = hahde, OR, NO3, RCO2, L = NH3, primary, secondary, and tertiary amines, py n = 2-4), U02(N03)2L (L = en, diamiaobenzene n = 1, 2). The use of thiocyanates has lead to the isolation of typically 6 or 8 coordinate neutral and anionic species, ie, [U02(NCS)J j)/H20 (x = 2-5). 

Aziridines also undergo ring enlargement when treatment with thiocyanic acid, cis- and tran5-2,3-Dimethylaziridine (470) with thiocyanic acid gave exclusively trans- and cis-1-amino-4,5-dimethyl-2-thiazoline (471) (72JOC4401). 

Pseudohalides of Se in which the role of halogen is played by cyanide, thiocyanate or selenocyanate are known and, in the case of Se are much more stable with respect to disproportionation than are the halides themselves. Examples are Se(CN)2, Se2(CN)2, Se(SeCN)2, Se(SCN)2, Se2(SCN)2. The selenocyanate ion SeCN is ambidentate like the thiocyanate ion, etc., p. 325), being capable of ligating to metal centres via either N or Se, as in the osmium(IV) complexes [OsCl5(NCSe)], [OsCl5(SeCN)], and trans-[OsCU(NCSe)(SeCN)]2-.920) Tellurium and polonium pseudohalogen analogues include Te(CN)2 and Po(CN)4 but have been much... 

In many cases, it has been found that 7r-bonding ligands favour S-bonding. In a complex with both N- and S-bonded thiocyanate (Figure 3.74) the N-bonded group is trans to P while the sulphur-bonded thiocyanate is trans to the harder nitrogen ( anti-symbiosis ). 

Au(C6F5)Cl2(CH2PPh2Me)] reacts with potassium thiocyanate to give trans-... 

The dependence of rate constants for approach to equilibrium for reaction of the mixed oxide-sulfide complex [Mo3((i3-S)((i-0)3(H20)9] 1+ with thiocyanate has been analyzed into formation and aquation contributions. These reactions involve positions trans to p-oxo groups, mechanisms are dissociative (391). Kinetic and thermodynamic studies on reaction of [Mo3MS4(H20)io]4+ (M = Ni, Pd) with CO have yielded rate constants for reaction with CO. These were put into context with substitution by halide and thiocyanate for the nickel-containing cluster (392). A review of the chemistry of [Mo3S4(H20)9]4+ and related clusters contains some information on substitution in mixed metal derivatives [Mo3MS4(H20)re]4+ (M = Cr, Fe, Ni, Cu, Pd) (393). There are a few asides of mechanistic relevance in a review of synthetic Mo-Fe-S clusters and their relevance to nitrogenase (394). 

The parent 4-oxo-2-thioxopyrimidines 305 (cis, n = 1, 2 trans, n = 2 R = H), 306 cis or trans), 307 and 308 diendo and diexo) were prepared analogously to pyrimidinediones by reacting the corresponding amino ester hydrochlorides with potassium thiocyanate (89MRC959), or from alicyclic ethyl 2-isothiocyanato-l-carboxylates, obtained by the reaction of amino esters and thiophosgene with ammonia (96UP2). 

The 4-oxo-2-thioxopyrimidines 472 (cis, X = CH2, CH2CH2 trans, CH = CH, CH2CH2), readily prepared from amino esters with potassium thiocyanate, gave the tricyclic 1,3-thiazinopyrimidinones 473 by addition of dimethyl acetylene dicarboxylate (DMAD) (89MRC959). In this reaction, the first step is probably a Michael addition of DMAD to the tautomeric 2-SH group, and thereafter cyclization of the ester on the ring NH occurs. 

This approach applies only when we are certain that the substrate is mainly in the form of the free ion at the lowest anion concentrations. This is true in the chloride exchange of cw-[Co en2 Cl2]+ in methanol and we can safely conclude that the mechanism is unimolecular (8, 9. 10, 11, 26, 27). This condition did not exist when we studied the displacement of water in trans-[Co en2N02H20]+2 by anions where, because of the large ion association constants, none of the substrate was in the free ion form under reaction conditions. However, in the reaction between trans-[Co en2N02Br]+ and thiocyanate in sulfolane, the substrate was mainly in the free ion form. The observed second-order kinetic form was fully consistent with assigning a bimolecular mechanism to the rearrangement of the ion pair. 

Katritzky Gruntz Mongclli Rczende J. Chem. Soc., Perkin Trans. 1 1979, 1953. For the conversion of primary alcohols to thiocyanates, see Tamura Kawasaki Adachi Tanio Kita Tetrahedron Lett. 1977, 4417. 

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