Magnesium(II) Complexes of 2,4-N,N′-Disubstituted 1,3,5-Triazapentadienyl Ligands: Synthesis and Characterization of [N(Dipp)C(NMe2)NC(NMe2)N(SiMe3)MgBr]2 and [N(R)C(R′)NC(R′)N(SiMe3)]2Mg (Dipp = 2,6-iPr2−C6H3, R = Ph, SiMe3; R′ = NMe2, 1-piperidino)

Treatment of the appropriate lithium or sodium 2,4-N,N′-disubstituted 1,3,5-triazapentadienate [RNC(R′)NC(R′)N(SiMe3)M]2 (R = Ph, 2,6-iPr2−C6H3(Dipp) or SiMe3; R′ = NMe2 or 1-piperidino; M = Li or Na) with one or half equivalent portion of MgBr2(THF)2 in Et2O under mild conditions furnishes in good yield the first structurally characterized molecular magnesium 2,4-N,N′-disubstituted 1,3,5-triazapentadienates [DippNC(NMe2)NC(NMe2)N(SiMe3)MgBr]2 (1), [{RNC(R′)NC(R′)N(SiMe3)}2Mg] (R = Ph, R′ = NMe2 2; R = Ph, R′ = 1-piperidino 3; R = SiMe3, R′ = 1-piperidino 4). The solid-state structure of 1 is dimeric and those of 2, 3, and 4 are monomeric. The ligand backbone NCNCN in 1 adopts a W-shaped configuration, while in 2, 3 and 4 adopts a U-shaped configuration.