Synthesis and structures of some bimetallic (Li/Ca, Li/Zn, Li/Li) diamides derived from 1,2-bis(neopentylamino)benzene and of Li2[{N(SiMe2NPr(i)2)}2C6H4-1,2](thf)3

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] (H(2): R = CH2But; H2L': R = SiMe2NPri2): Li(thf)(mu-L)(mu-I)Ca(thf)] (1), Li(thf)4]{Zn(mu-L)}3(mu3-Cl)] (2), Li(thf)4]Zn(L)2] (3), {Li(OEt2)(mu-L)Zn}2(mu-L)] (4), Li(OEt2)(mu-L)Zn(mu-L)Zn(LH)] (5) and Li(thf)(mu-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.