Lithium, Magnesium, and Zinc Centers N,N'-Chelated by an Amine-Amide Hybrid Ligand.

The synthesis and structure of lithium, magnesium, and zinc complexes N , N '-chelated by a hybrid amine-amido ligand ([2-(Me 2 NCH 2 )C 6 H 4 NR] - , abbreviated as L N R, where R = H, SiMe 3 , or Bn) are reported. The reaction of the least sterically demanding L N H with various magnesium sources gives the hexameric imide [L N Mg] 6 ( 4 ) by the elimination of n -butane from L N HMg n Bu ( 2 ) or by the reaction of L N HLi ( 1 ) with MeMgBr. [L N H] 2 Mg ( 3 ) is obtained through the addition of 0.5 equiv of n Bu 2 Mg or Mg[N(SiMe 3 ) 2 ] 2 to L N H 2 and with 1 equiv of n Bu 2 Mg reacting to 2 . Both L N HMgN(SiMe 3 ) 2 ( 6 ) and isostructural L N HZnN(SiMe 3 ) 2 ( 16 ) have been prepared using two different approaches: monodeprotonation of L N H 2 by Zn/Mg[N(SiMe 3 ) 2 ] 2 in a 1:1 ratio or ligand substitution of 2 or L N HZnEt ( 12 ) by 0.5 equiv of Sn[N(SiMe 3 ) 2 ] 2 . The reactions of 2 or 3 with 1 provide the heterotrimetallic complex [L N H] 4 Li 2 Mg ( 5 ). Benzyl- or trimethylsilyl-substituted anilines [L N (SiMe 3 )H ( 7 ) and L N (Bn)H ( 8 )] with 0.5 equiv of n Bu 2 Mg allow the formation of homoleptic bis(amides) of the [L N (R)] 2 Mg type ( 10 and 11 ). Nevertheless, only the silylated secondary amine 7 is able to provide the heteroleptic n -butylmagnesium amide L N (SiMe 3 )Mg n Bu ( 9 ) upon reaction with an equimolar amount of n Bu 2 Mg. Similarly, 12 , [L N H] 2 Zn ( 13 ), L N (R)ZnEt ( 17 and 18 ), and [L N (R)] 2 Zn [R = SiMe 3 ( 19 ) and Bn ( 20 )] were prepared by the monodeprotonation of L N H 2 or L N (R)H using Et 2 Zn in the corresponding stoichiometric ratio. L N HZnI was prepared by the nucleophilic substitution of an ethyl chain in 12 by molecular iodine. A heterometallic complex, [L N H] 4 Li 2 Zn ( 14 ), analogous to 5 was prepared from 12 or 13 with 1 or 2 equiv of 1 , respectively.