Thiazyl monomer

Thiazyl monomer is a radical with one unpaired electron. It exhibits an IR band at 1209 cm-1. The experimental dipole moment is 1.83 0.03 D in the opposite direction to that in NO (p = 0.16 D). Much less is known about selenazyl monomer, SeN, but it has been characterized by infrared spectroscopy.36 The structure of a transition-metal complex [OsTp(NSe)Cl2] (Tp=hydrotris(l-pyr-azolyl)borate) has been determined.39... 

Thiazyl monomer can be stabihzed by coordination to a metal, and many thionitrosyl complexes with Cr, Mo, Re, Ru, Os, Co, Rh, Ir, and Pt are known. Comparison of the spectroscopic properties and the electronic stmctures of M-NS and M NO complexes indicates that NS is a better a-donor and jr-acceptor ligand than NO. Oxygen transfer from an NO2 to an NS ligand on the same metal center occurs in ruthenium porphyrin complexes. ... 

Thiazyl monomer, SN, polymerizes readily in the solid or liquid phases and has only a transient existence in the gaseous phase. It is formed by the passage of an electric discharge through sulfur vapor and nitrogen or SFg and nitrogen, from the reaction of active nitrogen with HjS or SClj or from flash photolysis of a mixture of COS and NF 3 ... 

Thiazyl monomer is a radical with one unpaired electron. In contrast to nitric oxide, it polymerizes so readily that it cannot be isolated as a monomeric solid or liquid and has only a transient existence in the gas phase. Thiazyl monomer may be generated in a number of ways, including the volatilization of (SN) c (2) or pyrolysis of S4N4 (1) over quartz wool above 300 °C. The emission spectrum and ESR spectrum have been reported. The bond length is calculated to be 149.7 pm from its spectroscopic moment of inertia. This indicates a bond order of between two and three. The dissociation energy of this strong sulfur-nitrogen bond is estimated to be 463 kj mol from spectroscopic data. Nevertheless, like other sulfur nitrides, NS is endothermic and unstable with respect to its elements. Thiazyl monomer exhibits an IR band at 1209 cm T The experimental dipole moment is 1.83 0.03 D and the ionization potential is 9.85 eV. 

Monomeric thiazyl halides can be stabilized by coordination to transition metals and a large number of such complexes are known (Section 7.5). In addition, NSX monomers undergo several types of reactions that can be classified as follows (a) reactions involving the n-system of the N=S bond (b) reactions at the nitrogen centre (c) nucleophilic substitution reactions (d) halide abstraction, and (e) halide addition. Examples of each type of behaviour are illustrated below. 

Thiazyl halide monomers undergo a variety of reactions that can be classified under the general headings (a) reactions involving the 7i-system of the N = S triple bond, (b) nucleophilic substitution, (c) halide abstraction, and (d) halide addition. The cycloaddition of NSF with hexafluoro-1,3-butadiene provides an example of a type (a) reaction. 

Considerable interest has been shown in the reaction of 1,3,5-trichlorotrithiatriazine with nucleophiles in order to prepare new heterocyclic S—N systems. Most of the preparative routes to dithiatriazines involve the reactions of nitriles with thiazyl chloride monomer or dimer.18 20,22 However, these methods generally lead to a mixture of products.The silylated imidamide 1 was found to be a mild selective reagent in the reaction with trichlorotrithiatriazine 2.23 Thus, 7-phenyl-l A4, 3/l4-,5/l l-trithia-2,4,6,8,9-pentaazabicyc]o[3.3.1 ]nona-1(9),2,3,5,7-pcn-taene (3) can be prepared in dichloromethane solution from silylated benzimidamide 1 and trichlorotrithiatriazine 2. The molecule8 can be described in terms of a 1,3,2,4.6-dithiatriazine bridged by a N-S-N fragment across the 1,3-sulfur atoms. 

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). 

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