Thionitrites bonding

The red [SSNO] anion (37) is produced by the reaction of an ionic nitrite with elemental sulfur or a polysulfide in acetone, DMF or DMSO.115 The [SSNO] anion has a planar cis structure with a short S-S distance (1.99 A), and S-N and N-O distances of 1.67 and 1.22 A, respectively. The treatment of [SSNO]- with triphenylphosphine produces the thionitrite anion [SNO]- (38) with a bond angle of ca. 120° at nitrogen and S-N and N-O bond lengths of 1.69 and 1.21 A, respectively. 

Sulfurdiimines RN=S=NR and thionitrites RN=S=0 (R = alkyl, aryl) have been relatively little investigated as ligands in metal complexes. This lack of attention has been little deserved as both types of ligands have interesting ambident coordination properties, since they may bind via N, S, O, the 7t-N=S or jr-S=0 bond for example. They may be compared with allenes and naturally also with the isostructural and the isoelectronic sulfur dioxide 0=S—O.13 We will first discuss some relevant data concerning RNSNR and RNSO and subsequently the properties of the metal complexes. 

The sophistication of the physicochemical details of the photodissociation process of the ONO bond of prototype alkyl nitrites, such as methyl, ethyl, and t-butyl nitrites,(and the SNO bond of thionitrites °) in the gas phase, in matrix isolated states," in adsorbed states and at a shorter wavelength band (Sj state), etc. is continuing today through newer techniques. These aspects are beyond the present discussion. 

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