Metal derivatives of N1-substituted thiosemicarbazones: Synthesis, structures and spectroscopy of nickel(II) and cobalt(III) complexes

Reactions of nickel(II) and cobalt(II) salts with various N1-substituted thiosemicarbazones [R1R2C2N3–N2H–C1(S)–N1HR3, H2L; R1 = C6H5-, R2 = H, H2L1(R3 = Me); H2L2(R3 = Ph), R1 = 2-OHC6H4-, R2 = H, H2L3(R3 = Me), H2L4(R3 = Et), H2L5(R3 = Ph); R2 = Me, H2L6(R3 = Me), R2 = Me, H2L7(R3 = Et) and R2, R3 = H, Me, H2L8(R1 = C4H3S), H2L9(R1 = C4H3O)] are described. Reactions of Ni(OAc)2 with the ligands having R1 as phenyl group at C2 carbon (H2L1, H2L2) gave complexes, [Ni(κ2-N3, S-HL)2] (HL− = HL1, 1; HL2, 2). Other ligands with R1 as 2-hydroxyphenyl groups, namely, H2L3–H2L7, with Ni(OAc)2 yielded rust colored compounds, {Ni(κ3-O, N3, S–L)} (L2− = L3–L7) which after the addition of PPh2-CH2-PPh2 yielded dinuclear, [Ni2(κ3-O, N3, S–L)2(μ-P, P–PPh2–CH2–PPh2)] (L2− = L3, 3; L4, 4; L5, 5) and mononuclear, [Ni(κ3-O, N3, S–L)(κ1-P–PPh2–CH2–PPh2)] (L2− = L6, 6; L7, 7) complexes. Likewise, {Ni(κ3-O, N3, S-L5} with 2-phenylpyridine(2-Phpy) has yielded a mononuclear complex, [Ni(κ3-O, N3, S–L5)(κ1-N-2-Phpy)] 8. The geometry around Ni metal center can be formally described as square planar in each of complexes 1–8. Reactions of CoCl2 with H2L8 and H2L9 involved oxidation of CoII to CoIII and yielded octahedral complexes, [Co(κ2-N, S–HL)3] (HL− = HL8, 9; HL9, 10).