New Routes to Soluble Magnesium Amidoborane Complexes

Several new synthetic routes to the known and new magnesium amidoborane complexes, [{(Nacnac)Mg(NH2BH3)}2] and [(Nacnac)Mg(NH2BH3)(THF)] (Nacnac = DipNacnac, [{N(Dip)C(Me)}2CH]–, or tBuNacnac, [{N(Dip)C(tBu)}2CH]–; Dip = C6H3iPr2‐2,6), are reported. These include the reductive dehydrogenation reaction of NH3BH3 (AB) with the magnesium(I) dimer, [{(DipNacnac)Mg}2], and the salt elimination reaction of [(DipNacnac)MgI(OEt2)] with Li(NH2BH3). Moreover, the reaction of ammonia–borane with two magnesium(II) hydride complexes, [{(Nacnac)Mg(μ‐H)}2], or an alkylmagnesium(II) complex [{(DipNacnac)Mg(μ‐nBu)}2], have been shown to yield well defined parent amidoborane complexes of magnesium for the first time. The crystal structures of all prepared complexes were obtained and shown to be similar to those previously reported for related compounds. Several new synthetic routes to soluble magnesium parent–amidoborane complexes are reported. These include the reductive dehydrogenation of ammonia–borane (AB) with a magnesium(I) dimer.