Synthesis and Chemical Transformations of 1,3-Diaryltetrazolium Salts. Preparation of Mercury(II) and Palladium(II) Complexes of 1,3-Diaryltetrazolylene and Reactions of 5-Substituted 1,3-Diphenyltetrazolium Salts with Nucleophiles

1,3‐Diaryltetrazolium salts 5 and 6 have been prepared by nitric acid oxidation of the corresponding 5‐thiolates 4. The reaction of 5 with mercury(II) acetate gives (1,3‐diaryltetrazolylene)mercury(II) complexes 7, which provide 5‐halotetrazolium salts 8 – 10 by treatment with halogen. 1,3‐Diphenyltetrazolylene (16), generated in situ by proton ion of 1,3‐diphenyltetrazolium salts 5a or 6a, has been trapped with p‐(dimethylamino)benzenediazonium tetrafluoroborate to form 18/18′. The palladium(II) complex 19 of 1,3‐diphenyltetrazolylene has been prepared by oxidative addition of tetrakis(triphenylphosphane)palladium(0) to 5‐chlorotetrazolium salt 8. The reactivity of various 5‐substituted tetrazolium salts toward carbon nucleophiles depends on the nature of the substituents at C‐5. With electronegative substituents, nucleophilic substitution proceeds at C‐5, whereas electron‐donating substituents direct the nucleophiles towards N‐2 yielding ring‐cleaved products.