The present volume describes acyclic Sulfur-nitrogen compounds with sulfur of the oxida- tion number II. The first chapter deals with sulfur imide (S=NH), N-organyl-sulfur imides (S=NR, R = or- ganyl), and metal complexes of sulfur imides. N-Organyl-sulfur imides have not been isolated, but they can be trapped, for example, by cycloaddition and stabilized by coordination to transi- tion metals. 11 The following chapter present a detailed survey of other 8 -N compounds with one- coordinate sulfur, e.g., dithionitrous acid (S=N-SH) and derivatives, the salts of the dithionitryl ion (1 +) ([S=N=S]+), and N-thionitroso-diorganyl-amines (S=NNR , R = organyl). Only the reac- 2 tions of [S=N=S]+ AsF5, among the known [S=N=S]+ salts, have been extensively studied. Cycloadditions with alkenes and triple bonded compounds produce 1 ,3,2-dithiazolium salts and their derivatives. S=NN(CH )z and S=NN(C H )z form transition metal complexes. The 3 6 5 Iigand is coordinated via the S atom in a monodentate manner.

PF3, (CH3)3SiCl -> (CH3)3SiF, and RC(O)Cl -> RC(O)F. Others include the conversion of (C6H5)3P into (C6H5)3PF2 and of (R3NC(S)S)2 into R2NCF3, R=alkyl. In organic chemistry, fluorides are easily accessible from alcohols, geminal fluorides RR'CF2 from the respective aldehydes or ketones, and acyl fluorides RC(O)F from carboxylic acides by using DAST. Because DAST is easy to handle and gives clean reactions in syntheses, this Gmelin volume devotes much space to the description of the chemical and physical properties od DAST.