Cyclic arsenic-nitrogen cations.
A series of different cyclo-diarsa-diazenium salts bearing several bulky groups such as supermesityl (Mes* = 2,4,6-tBu(3)C(6)H(2)) and m-terphenyl (2,6-Mes(2)-C(6)H(3), Mes = 2,4,6-Me(3)C(6)H(2)) and anions such as triflate (OTf = SO(3)CF(3) = trifluoromethylsulfonate) and tetrachloridogallate (GaCl(4)(-)) were synthesized and fully characterized. The novel 1-chloro-cyclo-1,3-diarsa-2,4-diazenium cation represents the first example of a binary cyclic As(III)/N four-membered heterocyclic cation, with a di- and tricoordinated As atom and a delocalized pi bond along the NAs((+))N unit. The addition of excess Me(3)SiN(3) yields the fully characterized cationic arsenic azide, 1-azido-cyclo-1,3-diarsa-2,4-diazenium-mu-azido-hexachlorido-digallate. The Cl(-)/N(3)(-) exchange is triggered by the action of the Lewis acid GaCl(3). Depending on the Me(3)SiN(3) stoichiometry, different mu-azido-hexachlorido-digallate salts with either 1-chloro- or 1-azido-cyclo-1,3-diarsa-2,4-diazenium cations or even a mixture of both are observed. Moreover, it was of special interest to study the distances between the cationic arsenic center and the anion in cyclo-diarsa-diazenium salts. A correlation between the color of the salt and the anion/cation distance, ranging between 2 and 8 A in cyclo-diarsa-diazenium salts of the type [R(2)N(2)As(2)Y](+)X(-) depending on the bulky group R (R = Mes*, Ter), the substituent Y (Y = Cl, N(3), OTf), and the anion X(-) (X = OTf, GaCl(4), Cl(3)Ga-N(3)-GaCl(3)), was established.
Schulz
Axel
A
Universität Rostock Institut für Chemie Albert-Einstein-Str.3a, 18059 Rostock, Germany. axel.schulz@uni-rostock.de
Villinger
Alexander
A