Synthesis and structural characterization of metal complexes of 2-formylpyrrole-N-4-ethylthiosemicarbazone (4EL(1)) and 2-acetylpyrrole-N-4-ethylthiosemicarbazone (4EL(2))

The reactions of N-4-ethyl-2-[1-(pyrrol-2-yl)methylidene(hydrazine carbothi oamide (4EL(1)) and N-4-ethyl-2[1-(pyrrol-2-yl)ethylidene(hydrazine carboth ioamide (4EL(2)) with Group 12 metal halides afforded complexes of types [M (L)(2)X-2] (M = Zn, Cd; L = 4 EL1, 4 EL2; X = Cl, Br, I; 1-6, 14-19) and [M (L)X-2] (M = Hg; L = 4 EL1, 4 EL2,; X = Cl, Br, I; 7-9, 20-22). In addition , reaction of 4EL(1) with salts of Cu-II, Ni-II, Pd-II and Pt-II afforded c ompounds of type [M(4 EL1-H)(2)] (10-13). The new compounds were characteri zed by elemental analysis, FAB mass spectrometry, IR and electronic spectro scopy and, for sufficiently soluble compounds, H-1, C-13 and, when appropri ate, Cd-113 or Hg-199 NMR spectrometry. The spectral data suggest that in t heir complexes with Group 12 metal cations, both thiosemicarbazones are neu tral and S-monodentate; and for [Zn(4 EL1)(2)I-2] (3), [Cd(4EL(1))(2)Br-2] (5) and [Hg(4EL(1))CI2](2) (7) this was confirmed by X-ray diffractometry. By contrast, in its complexes with Cull and Group 10 metal cations, 4EL(1) is monodeprotonated and S,N-bidentate, as was confirmed by X-ray diffractom etry for [Ni(4EL(1)-H)(2)] (11) and [Pd(4EL(1)-H)(2)] (12).