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Reactions of nickel(II) and cobalt(II) salts with various N1-substituted thiosemicarbazones [R1R2C2=N3–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). [ABSTRACT FROM AUTHOR]

A series of palladium(II) complexes involving C–H and N–H bond activations of the R1 rings of thiosemicarbazones {R1(R2)C2–N3–N2(H)–C1(ᆖS)–N1HR3; R1, R2: thiopheneyl, Me, H2L1 (R3 = Me), H2L2 (R3 = Ph); R1, R2: Ph, Me, H2L3 (R3 = Me), H2L4 (R3 = Ph); R1, R2: Ph, Ph, H2L5 (R3 = Me), H2L6 (R3 = Ph) and R1, R2: pyrrole, Me, H2L7 (R3 = Me), H2L8 (R3 = Ph)} are described. Methyl group (R2) at C2 carbon in H2L1 and H2L2 induced C–H bond activation of the thiopheneyl ring and formed cyclometallated complexes, [Pd(κ3–C4,N3,S–L)(PPh3)] (L = L1, 1; L2, 2). Similarly, phenyl rings (R1) in H2L3, H2L4, H2L5, H2L6 at C2 carbon have shown C–H activations forming cyclometallated complexes, [Pd(κ3–C4,N3,S–L)(PPh3)] (L = L3, 3; L4, 4; L5, 5; L6, 6). However, pyrrole ring did not exhibit similar C–H activation behavior, rather involved N–H activation and formed complexes, [Pd(κ3–N4,N3,S–L)(PPh3)] {L = L7, 7; L8, 8}. All these complexes have been characterized with the help of analytical data, spectroscopic techniques (IR, 1H and 31P NMR), and single crystal X-ray crystallography (1, 2, 4, 5, 7 and 8). The thiosemicarbazone ligands behave as dinegative C4, N3, S-chelating in 1–6 and N4, N3, S-chelating in complexes 7 and 8. Interestingly, complexes 2, 4 and 8, with phenyl substituent at N1 atom, have two independent molecules in their respective crystal lattices. [ABSTRACT FROM AUTHOR]