The 1,1-ethene dithiolato ligands (dithioylidene barbituric acids) react with L2MCl2 [M = Pd, Pt; L = PEt3, PBu3, 1/2 dppe, 1/2 (-)-DIOP, 1/2 2,9-di-Me phenanthroline] to give the 1,1-ethene dithiolato metal complexes L2M[S2C:cyclo[CC(O)NR1C(O)NR2C](O)]. I (R = H, R1 = H, L = PEt3) forms a 1:1 adduct (II) with 2,6-diaminopyridine. The compds. were characterized on the basis of their IR and NMR (1H, 13C, 31P) spectra. I (R = H, R1 = H, L = PEt3; R, R1 = H, L = 0.5 dppe; R = H, R1 = Me, L = PBu3) were further studied by x-ray structural anal. The barbituric unit in I (R = H, R1 = H, L = PEt3) undergoes self-assembly through multiple hydrogen-bonding with complementary 2,6-diaminopyridine yielding the supramol. complex II. [on SciFinder (R)]