The chemistry of sulphur–nitrogen ligands. Part I. Complex-formation and dealkylation reactions of 1,9-bis(tritylthio)- and 1,9-bis(benzyl-thio)-3,7-diazanonane in the presence of metal(II) salts, and the synthesis of dibromo{3,13-dithia-6,10-diazabicyclo[13.4.0]nonadeca-1(15),16,18-triene}nickel(II)

Abstract

The quadridentate N₂S₂ donor ligands 1,9-bis(tritylthio)-3,7-diazanonane (L¹) and 1,9-bis(benzylthio)-3,7-diazanonane (L²) have been prepared as their dihydrobromide salts and allowed to react with metal(II) acetates (M = Ni^II, Co^II, and Hg^II) in methanol solution. Both ligands react with Hg^II with concomitant dealkylation at the sulphur donor atoms to give a trinuclear complex [Hg(HgL)₂]Br₂·3H₂O (L = 3,7-diazanonane-1,9-dithiolato). Treatment of this complex (dissolved in aqueous HCl) with H₂S gives the dihydrochloride of 3,7-diazanonane-1,9-dithiol. Dealkylation does not occur in the presence of Co^II, the isolated complexes in this case being blue tatrahedral [CoL¹]Br₂ and purple octahedral [CoBr₂(L²)]. Nickel(II) gives the blue octahedral [NiBr₂(L²)], but catalyses rapid detritvlation of L¹ to give the black. ₁diamagnetic, trinuclear complex [Ni(NiL)₂]Br₂. Reaction of [Ni(NiL)₂]Br₂, with α,α′-dibromo-o-xylene in methanol solution gives blue dibromo{3,13-dithia-6,10-diazabicyclo[ 13.4.0]nonadeca-1(15),16,18-triene}nickel(II).