Reactions of hydrazine with main group Lewis acids.

Hydrazine is reacted with main group Lewis acids including those with LUMOs derived from either vacant p-orbitals, or low lying σ* orbitals and of varying Lewis acidities. This is shown to give a diverse range of resulting products. For Lewis acids with vacant 2p-orbitals such as the boranes, BF3, Mes2BH, MesBH2, PhBBN, and C6F5BBN reacts with hydrazine gave the Lewis acid-base mono- and bis-adducts (F3B)2(N2H4) 1, Mes2BH(NH2NH2) 2, MesBH2(NH2NH2) 3, (PhBBN)2(NH2NH2) 4, and (C6F5BBN)NH2NH25, respectively. In contrast, the reaction of the 3p-Lewis acid [Et3Si(HSiEt3)]+ showed no evidence of Si-hydrazine coordination. Rather, the hydrazinium salt [(NH2NH2)2H][B(C6F5)4] 6 was obtained and prepared independently via reaction with triflic acid and subsequent anion exchange. Reaction of GaCl3 (a 4p-Lewis acid) with hydrazine afforded the polymeric species [Cl3GaNH2NH2]n7. The phosphonium bromides [R3PBr]Br (R = Ph, Et) are σ*-derived Lewis acids and react with hydrazine to afford the salts, [Ph3PNHNH2]Br 8 and [(Ph3PNH)2]X2 (X = Br 9, GaCl410) and [(Et3PNH)2]Br211 respectively. In contrast, the corresponding reaction of [(C6F5)3PCl]Cl afforded (H2NNHC6F4)3PO 12 which exhibited an extended H-bonding network structure in the solid state. These products of the reactions of Lewis acids with hydrazine are documented and the range of structural features discussed.