No abstract

Mono-and binuclear complexes of malonyl bis(thiosemicarbazide), H 4 MBT, with VO 2+ , Co 2+ , Ni 2+ , Cu 2+ , Cd 2+ and Pt 4+ have been isolated. The elemental analyses, magnetic moments, spectra [u.v.-vis., i.r., e.s.r. (for Cu 2+ ; VO 2+ ) and mass], thermal and voltammetric measurements [for Co 2+ and Ni 2+ ] have been used to characterize the isolated complexes. The ligand behaves as binegative quadridentate with Cu 2+ , Co 2+ and VO 2+ ions, binegative pentadentate with Pt 4+ and hexadentate, either as trinegative in [Cd 2 (HMBT)(OC 2 H 5 )(C 2 H 5 OH)]H 2 O or mononegative in [Ni 2 (H 3 MBT)(OAc) 3 (C 2 H 5 OH)]. The lack of thiol and/or enol hydrogen during the complex formation was confirmed pH-metrically. The pK's (10.70, 8.50 and 8.15) of H 4 MBT reveal the removal of CSNH protons in one step and CONH in two steps. Also, the stability constants reveal a higher value for the Cu 2+ complex and a lower one for VO 2+ . The TG analyses suggest high stability for most complexes followed by thermal decomposition in different steps. The kinetic and thermodynamic parameters for some decomposition steps in VO 2+ and Pt 4+ thermograms have been calculated.

No abstract

No abstract

No abstract

Synthetic procedures are described that allow access to the new complexes cis-[Mo 2 O 5 (apc) 2 ], cis-[WO 2 (apc) 2 ], trans-[UO 2 (apc) 2 ], [Ru(apc) 2 (H 2 O) 2 ], [Ru(PPh 3 ) 2 (apc) 2 ], [Rh(apc) 3 ], [Rh(PPh 3 ) 2 (apc) 2 ]ClO 4 , [M(apc) 2 ], [M(PPh 3 ) 2 (apc)]Cl, [M(bpy)(apc)]Cl (M(II) = Pd, Pt), [Pd(bpy)(apc)Cl], [Ag(apc)(H 2 O) 2 ] and [Ir(bpy)-(Hapc) 2 ]Cl 3 , where Hapc, is 3-aminopyrazine-2-carboxylic acid. These complexes were characterized by physicochemical and spectroscopic techniques. Both Hapc and several of its complexes display significant anticancer activity against Ehrlich ascites tumour cells (EAC) in albino mice.

The reaction between nitric oxide and the naturally occurring carotenoid (3-carotene is shown by EPR and optical spectroscopy to produce a series of nitroxides with concomitant loss in conjugation of the (3-carotene molecule, with a rate constant of ca. lo3 dm3 mol-1.

No abstract