Synthesis and structures of some bimetallic (Li/Ca, Li/Zn, Li/Li) diamides derived from 1,2-bis(neopentylamino)benzene and of Li2[{N(SiMe2NPri2)}2C6H4-1,2](thf)3

Abstract

The following crystalline, or microcrystalline (4), metal diamides have been prepared under mild conditions from the N,N′-disubstituted 1,2-diaminobenzene [{N(R)H}₂C₆H₄-1,2] (H₂L: R = CH₂Bu^t; H₂L′: R = SiMe₂NPrⁱ₂): [Li(thf)(µ-L)(µ-I)Ca(thf)] (1), [Li(thf)₄][{Zn(µ-L)}₃(µ₃-Cl)] (2), [Li(thf)₄][Zn(L)₂] (3), [{Li(OEt₂)(µ-L)Zn}₂(µ-L)] (4), [Li(OEt₂)(µ-L)Zn(µ-L)Zn(LH)] (5) and [Li(thf)(µ-L′)Li(thf)₂] (6). Compounds 1–5 were obtained from [Li₂(L)] and CaI₂ (1) or ZnCl₂ (2–5) while 6 was derived from H₂(L′) and LiBuⁿ. Compound 5 was isolated as a very minor by-product from the synthesis of 4, and is assumed to have been formed therefrom by adventitious hydrolysis. The green salt 3 was paramagnetic with the negative charge uniformly delocalised on the two ligands. The other compounds were colourless and diamagnetic. The X-ray structures of each, except 4, are reported and discussed.