Synthesis and attempted reductions of bulky 1,3,5-triazapentadienyl groups 2 and 13 halide complexes

Three extremely bulky 1,3,5-triazapentadienes, ^ArNNNH (^ArNNN = N{C(Bu^t)=N(Ar)}₂; Ar = Mes (mesityl), Dep (2,6-diethylphenyl), or Dip (2,6-diisopropylphenyl)) have been prepared and structurally characterized. These are readily deprotonated, yielding a series of lithium and potassium triazapentadienyl complexes, one of which, (^DipNNN)Li, has been structurally characterized. Similarly, three monomeric triazapentadienyl magnesium iodide complexes, (^ArNNN)MgI(OEt₂), and a dimeric calcium counterpart, {(^MesNNN)Ca(THF)(μ-I)}₂, have been prepared. Attempts to reduce the former gave homoleptic bis(triazapentadienyl) magnesium complexes, (^ArNNN)₂Mg (Ar = Mes or Dep) as the main products. One reaction also gave a very low yield of the magnesium(I) dimer, {(^DepNNN)Mg-}₂, which was structurally characterized. In related chemistry, two triazapentadienyl boron difluoride compounds, (^ArNNN)BF₂ (Ar = Mes or Dep), have been synthesized, and unsuccessful attempts have been made to reduce these to boron(I) heterocycles. For sake of comparison, attempts have been made to prepare a series of related amino-substituted β-diketiminato group 13 element(I) heterocycles. Although these were also not successful, several group 13 element(III) halide complexes incorporating this ligand class have been characterized.