Axial ligand influence on geometries, charge distributions and electronic structures of iron tetraazamacrocycle [Fe((II))TIM(X)(Y)](2+) complexes assessed by Density Functional Theory

We employed the Density Functional Theory along with small basis sets, B3LYP/LANL2DZ, for the study of FeTIM complexes with different pairs of axial ligands (CO, H(2)O, NH(3), imidazole and CH(3)CN). These calculations did not result in relevant changes of molecular quantities as bond lengths, vibrational frequencies and electronic populations supporting any significant back-donation to the carbonyl or acetonitrile axial ligands. Moreover, a back-donation mechanism to the macrocycle cannot be used to explain the observed changes in molecular properties along these complexes with CO or CH(3)CN. This work also indicates that complexes with CO show smaller binding energies and are less stable than complexes with CH(3)CN. Further, the electronic band with the largest intensity in the visible region (or close to this region) is associated to the transition from an occupied 3d orbital on iron to an empty pi* orbital located at the macrocycle. The energy of this Metal-to-Ligand Charge Transfer (MLCT) transition shows a linear relation to the total charge of the macrocycle in these complexes as given by Mulliken or Natural Population Analysis (NPA) formalisms. Finally, the macrocycle total charge seems to be influenced by the field induced by the axial ligands. (C) 2011 Elsevier Ltd. All rights reserved.

Ruthenium (II) phosphine/picolinate complexes as antimycobacterial agents

The synthesis, characterization and the anti-Mycobacterium tuberculosis (MTB) activities of three ruthenium complexes containing the 2-pyridinecarboxylic acid anion (picolinate), with formulae cis-[Ru(pic)(dppm)(2)]PF(6) (1), Cis- [Ru(pic)(dppe)(2)]PF(6) (2) and [Ru(pic)(2)(PPh(3))(2)] (3) [pic = 2-pyridinecarboxylate; dppm = bis(diphenylphosphino)methane: dppe = 1,2-bis(diphenylphosphino)ethane; PPh(3) = triphenylphosphine] are reported in this article. The complexes were characterized by elemental analysis, spectroscopic and electrochemical techniques. Their in vitro anti mycobacterial activity was determinated as the Minimum Inhibitory Concentration (MIC) for MTB cell growth, measured by the REMA method. The best MICs were found for complexes (1) and (2), with values of 0.78 and 0.26 mu g/mL, respectively. The results are comparable to or better than ""first line"" or ""second line"" drugs commonly used in the treatment of TB. (C) 2009 Elsevier Masson SAS. All rights reserved.

Organic additive-copper(II) complexes as plating precursors

Cu(II) ions previously coordinated with typical electroplating organic additives were investigated as an alternative source of metal for plating bath. The coordination complexes were isolated from reaction between CuSO(4) and organic additives as ligands (oxalate ion, ethylenediamine or imidazole). Deposits over 1010 steel were successfully obtained from electroplated baths using the complexes without any addition of free additives, at pH = 4.5 (H(2)SO(4)/Na(2)SO(4)). These deposits showed better morphologies than deposits obtained from CuSO(4) solution either in the absence or presence of oxalate ion as additive (40 mmol L(-1)), at pH = 4.5 (H(2)SO(4)/Na(2)SO(4))It is suggestive that the starting metal plating coordinated with additives influences the electrode position processes, providing deposits with corrosion potentials shifted over + 200 mV in 0.5 mol L(-1) NaCl (1 mV s(-1)). The resistance against corrosion is sensitive to the type of additive-complex used as precursor. The complex with ethylenediamine presented the best deposit results with the lowest pitting potential (-0.27 V vs 3.0 mol L(-1) CE). It was concluded that the addition of free additives to the electrodeposition baths is not necessary when working with previously coordinated additives. Thus, the complexes generated in ex-situ are good alternatives as plating precursors for electrodeposition bath. (C) 2009 Elsevier B.V. All rights reserved.

Synthesis and characterization of mono and polymeric cyclopalladated compounds: Crystal and molecular structure of [{Pd(dmba)(ONO(2))}(2)(mu-pz)] center dot H(2)O (pz = pyrazine)

In the treatment of cyclometallated dimer [Pd(dmba)(mu-Cl)](2) (dmba = N,N-dimethylbenzylamine) with AgNO(3) and acetonitrile the result was the monomeric cationic precursor [Pd(dmba)(NCMe)(2)](NO(3)) (NCMe=acetonitrile) (1). Compound 1 reacted with m-nitroaniline (m-NAN) and pirazine (pz), originating [Pd(dmba)(ONO(2))(m-NAN)] (2) and [{Pd(dmba)(ONO(2))}(2)(mu-pz)] center dot H(2)O (3), respectively. These compounds were characterized by elemental analysis, IR and NMR spectroscopy. The IR spectra of (2-3) display typical bands of monodentade O-bonded nitrate groups, whereas the NMR data of 3 are consistent with the presence of bridging pyrazine ligands. The structure of compound 3 was determined by Xray diffraction analysis. This packing consists of a supramolecular chain formed by hydrogen bonding between the water molecule and nitrato ligands of two consecutive [Pd(2)(dmba)(2)(ONO(2))2(mu-pz)] units. (c) 2008 Elsevier Ltd. All rights reserved.

Cationic and neutral phenylmercury(II) complexes with heterocyclic thione ligands. X-ray structures of [HgPh(dmpymtH)][BF(4)] center dot H(2)O and [{HgPh}(2)(mu-dtu)]

The neutral complex [HgPh(dmpymt)] 1 (dmpymtH = 4,6-dimethylpyrimidine-2(1H)-thione) reacts with HBF(4) to give the cationic complex [HgPh(dmpymtH)][BF(4)] 2. The X-ray molecular structure of the later revealed a [2+1] coordination sphere about the mercury(II) atom (C-Hg-S and Hg center dot center dot center dot N). In the dinuclear complex [(HgPh)(2)(mu-dtu)] 3 [dtuH(2) = 2,4(1H,3H)-pyrimidinedithione or dithiouracil] the coordination spheres are also [2+1] although dissimilar regarding the Hg center dot center dot center dot N secondary bonds. NMR spectroscopy ((1)H, (13)C and (199)Hg) studies were undertaken in solution and the results discussed in the light of the X-ray structures. (C) 2008 Elsevier B. V. All rights reserved.