Hetero- and Homoleptic Magnesium Triazenides

Using monoanionic triazenide ligands derived from biphenyl and m-terphenyl substituted triazenes Dmp(Tph)N3H (1a), (Me4Ter)2N3H (1b) or Dmp(Mph)N3H (1c) (Dmp = 2,6-Mes2C6H3 with Mes = 2,4,6-Me3C6H2; Me4Ter = 2,6-(3,5-Me2C6H3)2C6H3; Mph = 2-MesC6H4; Tph = 2-TripC6H4 with Trip = 2,4,6-i-Pr3C6H2), several magnesium triazenides were synthesized. Heteroleptic complexes [Mg(N3Ar2)I(OEt2)] (Ar2 = Dmp/Tph (2a), (Me4Ter)2 (2b) were obtained from metalation of the corresponding triazenes with di-n-butylmagnesium followed by reaction with iodine in diethyl ether as the solvent in high yields. Replacing diethyl ether by n-heptane afforded trinuclear compounds [Mg3(N3Ar2)2I4] (3a, 3b) in low yields in which a central MgI2 fragment is coordinated by two iodomagnesium triazenide moieties. Two unsolvated homoleptic magnesium compounds [Mg(N3Ar2)2] (4b, 4c) were obtained from di-n-butylmagnesium and triazenes 1b or 1c in a 1:2 ratio. Depending on the nature of the substituents, the magnesium center either shows the expected tetrahedral or a rather unusual square planar coordination.