NEW PATHWAYS IN TELLURIUM-CHALKOGEN-NITROGEN CHEMISTRY - PREPARATIONS, STRUCTURES, AND PROPERTIES OF TELLURAHETEROCYCLES

Treatment of Se(NSO)2 with TeF4 in CH2Cl2 yields the compounds [FTeNSNSeNSN+][TeF5-] (4a) and [SeNSNSe+]2-[TeF5-]2 (5b), while with TeBr4 after six months Br2TeNSNSe (2d) is formed. An almost quantitative yield of Cl4Te2N4S2 (6) is obtained from either Cl6Te2N2S (1a) and (CH3)3SiNSNSi(CH3)3 in CH2Cl2 at 20-degrees-C (2 d) or TeCl4 and (CH3)3SiNSO (molar ratio 1:2) in CH2Cl2 at 60-degrees-C (3 d). The use of (CH3)3SiOSi(CH3)3 as solvent in the last mentioned procedure gives 1a and small amounts of Cl2Te(NSO)2. Similarly, F2Te(NSO)2 is prepared from TeF4 and (CH3)3SiNSO in CH2Cl2. Dechlorination of 1a with (C6H5)3Sb leads to Cl2TeNSNTe (2a), which is also produced from TeCl4 and [(CH3)3Si]2NSN[Si(CH3)3]2. When TeF4 is used instead of TeCl4 (molar ratio 3:1) the salt [FTeNSNTe+][TeF5-] (7a) is formed. Similarly, [ClTeNSNTe+][AsF6-] (7b) is prepared from 2a and AsF5 or Ag+[AsF6-] in SO2. A new method for the preparation of bicyclic type 1 telluraheterocycles involves bromination of 2a yielding Cl2Br4Te2N2S (1b). Dehalogenation with (C6H5)3Sb converts 1b into Br2TeNSNTe (2b). When 2b is treated with Br2 in CH2Cl2 an oxidative halogenation takes place with formation of Br6Te2N2S (1c). Metathetical exchange between 2b and Ag+[AsF6-] gives [BrTeNSNTe+][AsF6-] (7c). Isostructural S(NSO)2 reacts with TeCl4 for several weeks at 60-degrees-C in CH2Cl2 to form S4N4 . TeCl4 and [S5N5+][Te3Cl13-], in contrast to the corresponding reaction with Se(NSO)2. The molecular structures of 4a, 7b, 8, and [S5N5+][Te3Cl13-] have been determined by X-ray diffraction methods. Spectroscopic data for all new compounds are presented.