beta-Diketonato complexes [Tl{CH{C(O)R}(2)}] or PPN[Au{CH{C(O)R}(2)}(2)] [where PPN = (Ph(3)P)(2)N] react with an excess of CS(2) to give, respectively, [Tl(2){S(2)C=C{C(O)R}(2)}](n)() [R = Me (1) or Ph (2)] or (PPN)(2)[Au(2){&mgr;-kappa(2)-S(2)C=C{C(O)R}(2)}(2)] [R = Me (3.PPN) or Ph (4.PPN)]. The gold complexes 3.PPN and 4.PPN can also be obtained from PPN[AuCl(2)] and the corresponding thallium 1,1-ethylenedithiolate. PPN[AuCl(4)] reacts with 1 to give PPN[Au{kappa(2)-S(2)C=C{C(O)Me}(2)}(2)] (5) which, in turn, reacts with PhICl(2), Br(2) or I(2) (1:1) to give PPN[AuX(2){kappa(2)-S(2)C=C{C(O)Me}(2)}] [X = Cl (6), Br (7), or I (8)]. By reacting 6 with TlCF(3)SO(3) and 1,10-phenanthroline (phen) in 1:2:1 molar ratio, the cationic complex [Au{kappa(2)-S(2)C=C{C(O)Me}(2)}(phen)]CF(3)SO(3) (9) can be obtained. The crystal structures of 5 and 6.0.5Me(2)CO have been determined. Third-order nonlinearities of 3.PPN, 3.Pr(4)N, 5, and 6 have been evaluated by the Z-scan technique; an increase in nonlinearity upon extending the pi-system is observed, with the anionic dimetallacycle containing two gold and four sulfur atoms in 3 responsible for the largest nonlinearities (approximately 100 x 10(-36) esu).