SYNTHESIS AND CHARACTERIZATION OF N,N'-DISUBSTITUTED 1,2-PHENYLENEBIS(AMIDO)TIN(II) COMPOUNDS - X-RAY STRUCTURES OF 1,2-C6H4[N(CH(2)BU(T))]SN-2 AND OF [1,2-C6H4(N(SIME(3)))SN-2](2)(TMEDA)

Cyclic bis(amido)tin(II) compounds 1,2-C6H4[N(R)]Sn-2 [R = SiMe(3) (4) , SiMe(2)Bu(1) (5) and CH(2)Bu(t) (6)], as well as (4)(2)(mu-tmeda) 7 have been obtained either from (i) the corresponding dilithium compoun d 1,2-C6H4[N(R)Li](2) 1-3 and SnCl2 for 4-6, respectively, (or for 4) 2 1 + [Sn(mu-Cl){N(SiMe(3))(2)}](2); or (ii) 1,2-C6H4[N(H)R](2) + Sn[N (SiMe(3))(2)](2) for 4-6; or for 7 from 4 and tmeda. Compounds 4-6 are monomeric, yellow, thermochromic (becoming redder on heating), diamag netic, crystalline and are lipophilic and sublimable in vacuo. Compoun d 7 is colourless. The molecular structures of 6 and 7 have been deter mined from single crystal X-ray diffraction data. Compound 6 crystalli ses in bimolecular aggregates, in which there is a weak eta-C-6...Sn c ontact.