Rosa Carballo

Synthesis, characterization and antifungal activity of group 12 metal complexes of 2-acetylpyridine-4N-ethylthiosemicarbazone (H4EL) and 2-acetylpyridine-N-oxide-4N-ethylthiosemicarbazone (H4ELO)

Abstract Reaction of group 12 metal halides in ethanol with the thiosemicarbazones 2-acetylpyridine-4N-ethylthiosemicarbazone (H4EL) and 2-acetylpyridine-N-oxide-4N-ethylthiosemicarbazone (H4ELO) produced the compounds [M(H4EL)X2] and [M(H4ELO)X2] [M=Zn(II), Cd(II) or Hg(II), X=Cl, Br or I]. The ligands and complexes were characterized by elemental analysis and by IR and NMR (1H, 13C, 113Cd, 199Hg) spectroscopy, and the structures of H4ELO·H2O and the complexes [Cd(H4EL)I2]·2DMSO, [Hg(H4EL)Br2]–DMSO, [Zn(H4ELO)Cl2] and [Zn(H4ELO)Br2] were determined by X-ray diffraction. The metal centers in the complexes have coordination number five, H4EL and H4ELO behaving as neutral NNS- and ONS-tridentate ligands, respectively. The coordination polyhedra are close to tetragonal pyramids, the degree of distortion towards trigonal bipyramids was estimated by τ calculation. Against the pathogenic fungi Aspergillus niger and Paecilomyces variotii, the mercury complexes of H4ELO had activities that at some doses exceeded that of nystatin.

One-dimensional fluorescent stacking structure based on zinc mixed-complex salt encapsulated within an ‘ice-like’ three-dimensional hydrogen-bonded water network

Self-assembly of the fluorescent mixed-complex salt [Zn(HL)(phen)2][Zn(L)(HL)(phen)]·13H2O (1) [HL = methyllactato(−1) and L = methyllactato(−2)] created an ‘ice-like’ three-dimensional open framework by hydrogen-bonded crystallisation water molecules that encapsulates an infinite stacking chains result of the intercalation of phenanthroline ligands of complex ions.

Three new modes of adenine-copper(II) coordination: interligand interactions controlling the selective N3-, N7- and bridging μ-N3,N7metal-bonding of adenine to different N-substituted iminodiacetato-copper(II) chelates

Abstract The reaction of Cu2CO3(OH)2, various N-substituted-iminodiacetic acids [RN(CH2CO2H)2)] and adenine (AdeH) in water yields crystalline samples of mixed-ligand copper(II) complexes of formulas [Cu(A)(N7AdeH)(H2O)]·H2O (A=N-methyl- or N-ethyl-iminodiacetato(2−); compounds 1 and 2, respectively), [Cu(B)(N3AdeH)(H2O)]·H2O (B=N-benzyl- or N-(p-methylbenzyl)-iminodiacetato(2−); compounds 3 and 4, respectively) as well as [Cu4(pheida)4(μ-N3,N7AdeH)2(H2O)4]·2H2O (pheida=N-phenethyl-iminodiacetato(2−)). Crystal structures of the acid H2pheida and compounds 1–5 are reported. H2pheida acid exhibits a typical zwitterionic structure. Copper(II) compounds were also studied by TG analysis (with FT-IR study of the evolved gasses), IR, electronic and ESR spectra and magnetic susceptibility data. The N-alkyl- or N-benzyl-like-iminodiacetato(2−) ligands (A or B) give complexes with Cu(II)/(A or B)/AdeH equimolar ratio, whereas pheida yields an unexpected tetranuclear compound with a 2:2:1 Cu(II)/pheida/AdeH molar ratio. In 1 and 2 AdeH binds to the metal by N7, whereas in 3 and 4 the N3 atom is used. An unexpected bridging μ-N3,N7AdeHdicopper(II) binding mode is found in the tetra-nuclear compound 5 (without interligand π,π-stacking interactions). These AdeHCu(II) binding modes have not been referred in the literature before. The difference in AdeHCu(II) binding modes in compounds 1 or 2 and 3 or 4 is rationalised on the basis of the absence or presence of a flexible N-benzyl-like substituent in the iminodiacetato(2−) ligand skeleton, which prevents or permits the interligand π,π-stacking interactions.

Synthesis, Structural Characteristics and Biological Activities of Complexes of ZnII, CdII, HgII, PdII, and PtII with 2-Acetylpyridine 4-Methylthiosemicarbazone

Reaction of 2-acetylpyridine 4-methylthiosemicarbazone (H4ML) with halides of zinc(II), cadmium(II), and mercury(II) afforded complexes of the form [M(H4ML)X2] [M = ZnII (1–3), CdII (4–6) or HgII (7–9); × = Cl, Br, or I]. Reaction of H4ML with K2PdCl4 and K2PtCl4 gave compounds of the form [M(4ML)Cl] [M = PdII (10) or PtII (11)]. In all the new compounds, which were characterized by elemental analyses, conductance measurements, and electronic, IR and 1H- and 13C-NMR spectroscopy, and by 113Cd-, 195Pt-, or 199Hg-NMR spectroscopy when relevant, the ligand is N,N,S-tridentate, coordinating to the metal centre through its pyridine and azomethine nitrogen atoms and its thiocarbonyl sulfur atom, as was confirmed by X-ray diffraction studies in the cases of 4· 2 DMSO, 5· 2 DMSO, 6· 2 DMSO, 7· 2 DMSO, 10, and 11. In in-vitro assays, only [Zn(H4ML)Cl2] and [Zn(H4ML)Br2] showed some sign of antifungal activity against Aspergillus niger or Paecilomyces variotii.

Solid state coordination chemistry of copper(II)/α-hydroxycarboxylato/2,2′-bipyridine systems

Abstract Four new two-ligand complexes of copper(II) with 2,2′-bipyridine and one of three different α-hydroxycarboxylic acids (lactic, H2LACO; 2-methyllactic, H2MLACO; and mandelic, H2MANO) were prepared. Complexes 1–3 of general formula [Cu(HL)2(bipy)]·nH2O (HL=monodeprotonated acid), were characterized by elemental analysis, IR, electronic and EPR spectroscopy, magnetic measurements and thermogravimetric analysis. Complexes 1 (HL=HLACO, n=2), 2 (HL=HMLACO, n=1) and 3a (the result of attempted recrystallization of 3, of formula [Cu(HMANO)(bipy)2](HMANO)·H2MANO·CH3CN were studied by X-ray diffractometry. The copper atom is in an elongated, tetragonally distorted octahedral environment in 1 and 2 and in 3a has a coordination polyhedron intermediate between a square pyramid and a trigonal bipyramid, as evaluated in terms of the parameter τ. In 1 and 2 the α-hydroxycarboxylato ligand is bidentate and monoanionic but in 3a there are three forms: a monodentate monoanion, a monoanionic counterion, and a neutral molecule.

Reaction of bromopentacarbonylrhenium(I) with ferrocenylcarbaldehyde thiosemicarbazones: the first X-ray diffraction studies of metal carbonyl complexes containing bidentate thiosemicarbazone ligands

Abstract The reactions of [ReBr(CO) 5 ] with ferrocenylcarbaldehyde thiosemicarbazones HL with different groups attached to the amide nitrogen (R=H, Me, Ph) yielded complexes [ReBr(CO) 3 (HL)] ( 1 ) in which, according to X-ray studies of 1a ·{(CH 3 ) 2 CO} and 1b ·1/2{CH 2 Cl 2 }, the thiosemicarbazone is N , S -bidentate and the geometry around the metal fac -octahedral. Compounds of formula [ReL(CO) 3 ] 2 ( 2 ) were then prepared by reaction of the corresponding adduct 1 with NaOMe in acetone. A complex of formula [ReL 2 (CO) 3 ] 2 ( 2b ′) was also obtained as a dissolvate by slow concentration of a solution of 1b in acetone. Single crystals of 2a and 2b obtained from the mother liquors are composed of centrosymmetric dimers formed by ReSRe bridges, where S is the thiolic sulfur of an N , S -bidentate thiosemicarbazonato ligand. Although 2b ·2{(CH 3 ) 2 CO} and 2b ′·2{(CH 3 ) 2 CO} have similar co-ordination spheres, they differ as regards the configuration of the thiosemicarbazonato ligand about the azomethine bond and certain bond lengths (notably ReN); it seems likely that the configuration of L 2− determines how close the rhenium can approach the N atom of the ligand, and hence the delocalization of the π electrons in the CNN fragment of the thiosemicarbazide chain. The mass, IR and UV–vis spectra of the complexes, and their electrochemical behavior, are also discussed.

Synthesis and structural characterization of complexes of Zn(II), Cd(II) and Hg(II) halides with 2-formylpyrrole thiosemicarbazone and 2-acetylpyrrole thiosemicarbazone

Abstract Reaction of 2-[1-(pyrrol-2-yl)methylidene]hidrazine carbothioamide (L1) and 2-[1-(pyrrol-2-yl)ethylidene]hidrazine carbothioamide (L2) with zinc(II) cadmium(II) and mercury(II) halides afforded complexes with formulae [M(L1)X2] [M, X=Zn, Cl (1); Cd, Cl (4); Hg, Cl (7); Hg, Br (8); Hg, I (9)], [M(L1)2X2] [M, X=Zn, Br (2); Zn, I (3); Cd, Br (5); Cd, I (6)], [M(L2)X2] [M, X=Cd, Cl (13); Hg, Cl (16); Hg, Br (17); Hg, I (18)] and [M(L2)2X2] [M, X=Zn, Cl (10); Zn, Br (11); Zn, I (12); Cd, Br (14); Cd, I (15)]. Crystals of 5, 18 and 15·CH3CN were studied by X-ray diffractometry, and all the new compounds were characterized by elemental analysis, mass spectrometry, IR and 1H and 13C NMR spectroscopy and, when pertinent and allowed by the solubility of the compounds, 113Cd or 199Hg NMR spectroscopy. In these complexes, the metal atoms are tetra-coordinate and the ligands are neutral and S-monodentate.

Inter-ligand interactions and the selective formation of the unusual metal–N3(adenine) bond in ternary copper(II) complexes with N-benzyliminodiacetato(2−) ligands

A novel mixed-ligand copper(II) complex with N-(p-methoxybenzyl)-iminodiacetato(2)) ligand (MOBIDA) and adenine (AdeH) of formula ½CuðMOBIDAÞðAdeHÞðH2OÞ� � H2O has been obtained. Its crystal structure reveals the selective formation of a rare Cu– N3(AdeH) bond, closely related to those reported by first time for compounds of general formula ½CuðBÞðAdeHÞðH2OÞ� � H2O, with B ¼ N-benzyl- or N-(p-methylbenzyl)-iminodiacetato(2)) ligands. Appropriate structural comparison reveals that the copper(II) coordination by less basic N3 heterocyclic donor of the nucleobase is controlled by a molecular recognition process involving the formation of an intra-molecular inter-ligand N7(imidazole-like)–H ��� O(carboxyl) bond and the inter-molecular inter-ligand p,p-stacking interaction between six membered rings of benzyl (MOBIDA) and AdeH. This stack generates multi-stacked infinite chains along the b-axis of the crystal. 2002 Elsevier Science B.V. All rights reserved.

Crystal structures of two new heptamolybdates and of a pyrazole incorporating a gamma-octamolybdate anion

Two new heptamolybdates, one containing calcium and imidazole and the other with urea and ammonium cations, have been prepared. X-ray crystallographic studies of single crystals of both compounds have been carried out. In the mixture of calcium and imidazole [(Himi)(4)][Ca(H2O)(6)(mu-O)(2)][Mo7O24]. 2(imi). 3H(2)O (1), the calcium(II) cation is surrounded by six water molecules and two oxygen atoms from the polyanion, and bridges in trans position two [Mo7O24](6-) polyanions forming a linear composite with alternating Mo7O24 and Ca(H2O)(6) units. The urea compound [CO(NH2)H](3)(NH4)(9)[Mo7O24](2). 5[CO(NH2)(2)]. 4H(2)O (2) presents [Mo7O24](6-) heptamolybdate anions bound by hydrogen bonds from NH4+, [CO(NH2)H] cations and H2O molecules. A new crystalline phase of a gamma-octamolybdate containing pyrazole coordinatively bound to molybdenum has also been prepared [(Hpyr)(4)][(pyr)(2)(Mo8O26)]CH3COCH3. 2H(2)O (3). The structure has been solved by X-ray diffraction from a single crystal. The Mo-N bond length is 2.262(3) Angstrom. All compounds have been characterised by IR,H-1 NMR and thermal analysis

Coordination polymers of copper(II) based on mixed N- and O-donor ligands: the crystal structures of [CuL2(4,4′-bipy)]n (L=lactate or 2-methyllactate)

The neutral polymeric complexes of copper(II) [CuL 2 (4,4′-bipy)] n , where L is an α-hydroxycarboxylato ligand, lactate in 1 , 2-methyllactate in 2 , were prepared and characterised structurally. The copper atom is in an elongated tetragonally distorted octahedral environment in both compounds. Both α-hydroxycarboxylato ligands are O , O ′-bidentate chelating monoanions and 4,4′-bipyridine acts as an N , N ′-bis(monodentate) bridging ligand creating a linear polymeric arrangement. The polymeric chains are interconnected by O hydroxyl H⋯O carboxy hydrogen bonds in a way that creates cavities that differ in size between 1 and 2 . Spectroscopic data are presented and discussed.