The thiazyl cation

Thiazyl salts were first prepared in 1971 by the reaction of NSF with AsFs or SbFs. They may also be obtained from (NSC1)3 by reaction with (a) AgiAsFe] in liquid SO2 (Eq. 5.9) or (b) AICI3 in CH2CI2 under the influence of heat or ultrasound.  

The sulfur-nitrogen bond length in thiazyl salts is about 1.42 A and the vibrational frequency [v(SN] occurs at 1437 cm in [SNJiAsFg]. The [SN] cation exhibits an N NMR resonance at ca. 200 ppm and this technique is useful for monitoring reactions of [SN] .  

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The thiazyl cation is used for the preparation of other important S-N compounds (Scheme 5.3). For example, the insertion reactions with S4N4... 

The thiazyl cation is used for the preparation of other S-N compounds (see Scheme 2). For example, the insertion reactions with S4N4 and SCI2 produce the S5N5+ (5) and C1SNSC1+ (21) cations respectively. Insertion of thiazyl cations into the metal-halogen bond of Re(CO)5X (X = Cl, Br) provides a route to thiazyl hahde complexes. 

A different type of behaviour is observed with the chloro Lewis acid BCI3. With this reagent halogen exchange occurs to produce the acyclic cation [N(SC1)2] , as the [BCU] salt, rather than NSCf. " Thiazyl trichloride NSCI3 is predicted to be unstable with respect to NSCl -1-Cl2. ... 

Polyheteroatom Cations of Nitrogen and Sulfur. The simplest stable S—N species is the NS+ thiazyl cation.940 A convenient synthesis is the reaction of excess AgAsF6 with S3N3CI3 in SO2.941 The bond length of the NS+ cation shows a pronounced temperature dependence (corrected value = 1.42 A), and of the two resonance structures N=S+ is stabilized by ionic interactions.942... 

Radicals have been known for many years to form organic paramagnetic materials with numerous magnetic properties (ferro- or ferri-magnetism, spin Peierls transition, spin frustration, spin ladder systems) (see [51-60] for verdazyl radicals, [61-68] for thiazyl radicals, [69] for nitronyl nitroxide and [70-78] for Tempo radicals) (Fig. 6). When they are in their cationic form, they are valuable candidates for an association with the M(dmit)2 systems they will then provide the magnetic properties thanks to their free electron(s), whereas the M(dmit)2 moieties will provide the electrical properties. 

Dithiadiazolylium cations (as the chloride salt) were first prepared in 1977 (77INCL143) from the reaction of thiazyl chloride 11 with organic nitriles. Thiazyl chloride 11 exists as a trimer 11a in the solid state (61AX562), but partial dissociation to the monomer lib occurs in the vapor phase (70IC1079) and in solution (88IC2749). 

Reaction of the sulfur-nitrogen cage, S4N414, with thiazyl chloride 11 in the presence of a chloride acceptor leads to the formation of salts of the 14-ir aromatic cation, S5N5+ (77IS188), 15. 

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