Formation of thiolene versus dithiolene species from TTBEO.: Crystal structures of [Au(ddtCO2Et)(PPh3)] and [Sn(ddtCO2Et)2Me2] {TTBEO = 2,5,7,9-tetrathiabicyclo[4.3.0]non-1(6)-en-8-one;: ddtCO2Et = 3-(ethoxycarbonylsulfanyl)-5,6-dihydro-1,4-dithiine-2-thiolate}

Thiolene gold(I) and tin(IV) complexes such as [Au(ddtCO(2)R)L] [L = PPh3, PPh2Me or AsPh3; R = Et or Me; ddtCO(2)R = 3-(alkoxycarbonylsulfanyl)-5,6-dihydro-1,4-dithiine-2-thiolate] and [Sn(ddtCO(2)R)(2)Me-2] have been obtained from solutions of TTBEO {2,5,7,9-tetrathiabicyclo[4.3.0]non-1(6)-en-8-one} with sodium ethoxide or methoxide and the corresponding halogeno-complexes [AuCl(L)] and SnMe2Cl2. Reaction of the same solutions with [N(PPh3)(2)](2)[ZnCl4] and [ZnCl2(N-N)] [N-N = 1,10=phenanthroline (phen) or 2,2'-bipyridine (bipy)] afforded the dithiolene complexes [N(PPh3)(2)](2)[Zn(dddt)(2)], [Zn(dddt)(phen)] and [Zn(dddt)(bipy)] which are the trans-metallating starting materials for the synthesis of dithiolene gold(I) and tin(IV) complexes [{Au-2(dddt)(AsPh3)}(n)]. [Au-2(dddt)(PPh3)(2)], [Au-2(dddt)(PPh2Me)(2)] and [Sn(dddt)Me-2]. The results point to the existence of both thiolene ddtCO(2)R(-) and dithiolene dddt(2-) species in TTBEO solutions with sodium alkoxide. The crystal structures of [Au(ddtCO(2)Et)(PPh3)] and [Sn(ddtCO(2)Et)(2)Me-2] confirm the presence of the ethoxycarbonylsulfanyl ligand.