Synthesis and resolution of 1,11-diamino-dibenzo[d,f][1,3]dioxepine: a route to new asymmetric ligands and their complexes.

Atropisomeric C2-chiral biaryldiamine ligand, dibenzo[d,f][1,3]-dioxepin-1,11-diamine (H2L, 1) and its platinum amido-bridged tetranuclear complex [(mu-L)2Pt4Me4(mu-Me2S)2] (2) were prepd. and characterized. The diamine 1 was successfully resolved with (+)-tartaric acid; however, the free diamine undergoes substantial racemization within 2 h. Reaction of 2-iodo-3-nitrophenol with methylene iodide and Ullmann intramol. coupling of the produced 1,1'-[methylenebis(oxy)]bis[2-iodo-3-nitrobenzene] afforded 1,11-dinitro-dibenzo[d,f][1,3]dioxepin, characterized by single-crystal x-ray anal. The title diamine 1 was obtained by redn. of the dinitro deriv. with hydrazine hydrate. A test on the coordinating ability of the diamine has produced a complex 2, its crystal structure was detd.