The key role of sulfur in thiosemicarbazone compounds. Crystal and molecular structure of [Pd{4-MeOC6H4C(Me)=NN=C(S)NHPh}(2)]

The reaction of thiosemicarbazones 4-MeOC6H4C(H)=NN(H)C(=S)NHMe (a), 4-MeOC 6H4C(H)=NN(H)C(=S)NHEt (b) and 4-MeOC6H4C(H)=NN(H)C(=S)NHPh (c), with Li-2[ PdCl4], K-2[PdCl4] or Pd(AcO)(2) leads to the tetranuclear palladium(II) co mpounds, [Pd {4-MeOC6H3C(H)=NN=C(S)NHMe}](4), (1a), [Pd {4-MeOC6H3C(H)=NN=( S)NHEt}](4) (1d) and [Pd {4 MeOC6H3C(H)=NN=C(S)NHPh}](4) (1c): the ligands are terdentate through the [C, N, S] atoms and they are deprotonated at the -NH- group. Reaction of thiosemicarbazones 3-MeOC6H4C(H)=NN(H)C(=S)NH Me ( d) and 3-MeoC(6)H(4)C(H)=MU(H)C(=S)NHEt (e), with Li-2[PdCl4] or K-2[PdCl4] gave the mononuclear palladium(II) compounds [Pd(3-MeOC6H4C(H)=NN-C(S)NHMe }(2)] (1d) and [Pd( 3-MeOC6H4C(H)=NN-C(S)NHEt)(2)] (1e); the ligands are bo nded only through the azomethine nitrogen and sulfur atoms. Treatment of th iosemicarbazone 4-MeOC6H4C(Me)-NN(H)=C(S)NHPh (f) with Li-2[PdCl4] gave the tetranuclear compound [Pd{ 4-MeOC6H3C(Me)=NN=C(S)NHPh}](4) (1f), which upo n treatment with bis(diphenylphosphino )methane, dppm in 1.2 molar ratio ga ve the dinuclear species [{ Pd[4-MeOC6H3C(Me)=NN=C(S)NHeh]}(2)(mu -Ph2PCH2P Ph2)] (2f). The recrystallization of 2f gave the chiral compound [Pd {4-MeO C6H4C(Me)=NN=C(S)NHPh}(2)] (3f). The molecular structure has been determine d by single-crystal diffraction, showing O . . .H and S . . .H hydrogen bon ding. (C) 2001 Elsevier Science B.V. All rights reserved.