Search

Here, we report the synthesis, characterization, crystal data and DFT calculation of a new water-soluble ruthenium(II) carbonyl complex. The trans -[Ru(CO)(NH 3 ) 4 P(O)(OH) 2 ]Cl is a robust complex in aqueous media. The p K a of 3.3 for the phosphorous acid ligand in this complex was measured by infrared spectroscopy. The trans -[Ru(CO)(NH 3 ) 4 P(O)(OH) 2 ] + exhibits just two slow reactions at pH 7.5: CO–Ru–P(O)(OH) 2 to CO–Ru–(O)P(OH) 2 isomerization ( k = 1.1 × 10 −5 s −1 at 25 °C) and subsequent P(O)(OH) 2 dissociation ( k = 1.7 × 10 −7 s −1 at 25 °C). The formation of O-bonded trans -[Ru(CO)(NH 3 ) 4 (O)P(OH) 2 ] + was supported by IR, UV–Vis and 31 P NMR spectroscopies and DFT calculations. [ABSTRACT FROM AUTHOR]

Abstract: Two copper(II) complexes, [Cu(sac)2(4-cypy)2(H2O)], 1 and [Cu(sac)2(4-Ampy)2(H2O)], 2 (4-cypy: 4-cyanopyridine; 4-Ampy: 4-aminopyridine) were prepared. Physicochemical properties of the complexes were studied by spectroscopic (solution UV–vis, diffuse reflectance and IR) techniques. Structural X-ray diffraction data could be obtained only for [Cu(sac)2(4-cypy)2(H2O)] that it crystallized in the tetragonal space group P4cc with a=b=15.313(1), c=13.240(1)Å, and Z=4 molecules per unit cell. The complex was cited on a crystallographic C 2-axis with the Cu(II) ion in a square–pyramidal environment, coordinated at the pyramid basis to the nitrogen atom of two saccharine anions [d(Cu–N)=2.011(3)Å] and the pyridine N-atom of two 4-cyanopyridine ligands [d(Cu–N)=2.038(4)Å]. The coordination was completed by a water molecule at the pyramid apex [d(Cu–Ow)=2.189(5)Å]. Elemental and spectroscopic analyses revealed an O-saccharinate coordination mode for complex 2 and a square–pyramidal structure. Only complex 2 retained its structure in methanolic solution. However, both complexes were able to catalyze the dismutation of superoxide anion (O2 −) (pH 7.5) at micromolar concentrations. Therefore, these complexes behaved as useful SOD-mimetic compounds. [Copyright &y& Elsevier]

Abstract: Cyclization of thiosemicarbazones derived from β-keto esters and β-keto amides (HTSC) in the presence of diphenyllead(IV) acetate was explored in methanol solution at room temperature and under reflux. All β-keto ester TSCs underwent cyclization to give the corresponding pyrazolone (HL), which, except in one case, deprotonated and coordinated the PbPh2 2+ moiety to form homoleptic [PbPh2(L)2] or heteroleptic [PbPh2(OAc)(L)] derivatives. Cyclization did not occur with β-keto amide TSCs and only [PbPh2(TSC)2] or [PbPh2(OAc)(TSC)] thiosemicarbazonates were isolated. The complexes were characterized by IR spectroscopy in the solid state and by 1H, 13C and 207Pb NMR spectroscopy in DMSO–d 6 solution, in which they evolve and decompose with time. Additionally, crystals of p-acetoacetanisidide thiosemicarbazone (HTSC10), [PbPh2(OAc)(L5)]·MeOH (HL5 =2,5-dihydro-3,4-dimethyl-5-oxo-1H-pyrazolone-1-carbothioamide), [PbPh2Cl(L2)] (HL2 =2,5-dihydro-5-oxo-3-phenyl-1H-pyrazolone-1-carbothioamide), [PbPh2(OAc)(TSC8)]·2MeOH (HTSC8 =acetoacetanilide thiosemicarbazone), [PbPh2(OAc)(TSC10)]·H2O and [PbPh2(OAc)(TSC11)]·0.75MeOH (HTSC11 = o-acetoacetotoluidide) were studied by X-ray crystallography. The complexes, monomers or dimers with almost linear C–Pb–C moieties, are compared with the corresponding derivatives of Pb(II). [Copyright &y& Elsevier]

Abstract: The reaction of dimethylthallium(III) hydroxide with picolinic acid (Hpic), 3-hydroxypicolinic acid (H23hpic) and 6-hydroxypicolinic acid (H26hpic) in an aqueous/methanol mixture afforded the complexes [TlMe2(pic)] (1), [TlMe2(H3hpic)] (2) and [TlMe2(H6hpic)] (3), respectively. Complex 3′, [NaTlMe2(6hpic)2] n , was obtained as a minor product from a methanolic solution of 3. Compounds 1–3 were characterized by IR and Raman spectroscopy and, in the cases of 1, 2 and 3′, by single-crystal X-ray diffraction. Complex 3′ is the first example of an H6hpic− heterobimetallic compound to be isolated. The 1H and 13C NMR spectra of 1 and 2 are also discussed. [Copyright &y& Elsevier]

Abstract: The reactions of PbPh2(OAc)2 with alkylglyoxylate thiosemicarbazones (HRGTSC, R=Et, Bu) afforded complexes of the type [PbPh2(GTSC)]·H2O, [PbPh2(RGTSC)2] and [PbPh2Cl(BuGTSC)]. The structures of HRGTSC (R=Me, Et, Bu), [PbPh2(OAc)(RGTSC)](R=Me, Et, Bu), [PbPh2Cl(BuGTSC)] and [PbPh2(GTSC)]·H2O have been studied by X-ray diffraction. [PbPh2(OAc)(RGTSC)] and [PbPh2(GTSC)]·H2O have [PbC2NO3S] kernels and the coordination sphere of the metal is pentagonal bipyramidal. [PbPh2Cl(BuGTSC)] has a [PbC2NOSCl] kernel and the coordination geometry around lead is pentagonal bipyramidal with one vacant site. Analysis of the bond distances in [PbPh2(GTSC)]·H2O suggests a significant affinity between diphenyllead(IV) and carboxylate donor groups, supporting a borderline acidic character for this organometallic cation. 1H and 13C NMR spectra in DMSO-d 6 suggest the partial dissociation of the acetate in [PbPh2(OAc)(RGTSC)] solutions and indicate some differences in the coordination mode of the two RGTSC− ligands in [PbPh2(RGTSC)2] complexes. [Copyright &y& Elsevier]

Abstract: New Pd(II) and Pt(II) complexes [ML2] (HL=a substituted 2,5-dihydro-5-oxo-1H-pyrazolone-1-carbothioamide) have been synthesized by reacting K2MCl4 (M=Pd, Pt) or Pd(OAc)2 with β-ketoester thiosemicarbazones. The structures of seven of these complexes were determined by X-ray diffraction. Although all exhibit a distorted square-planar coordination with trans- or (in one case) cis-[MN2S2] kernels, their supramolecular arrangements vary widely from isolated molecules to 3D-networks. The in vitro antitumoral assays performed with two HL ligands and their metal complexes showed significant cytostatic activity for the latter, with the most active [ML2] derivative (a palladium complex) being about sixteen times more active than cis-DDP against the cisplatinum-resistant cell line A2780cisR. [Copyright &y& Elsevier]

Abstract: The reaction of lead(II) acetate in methanol with thiosemicarbazones derived from β-keto esters and β-keto amides (HTSCs) afforded two lead(II) thiosemicarbazonates and numerous homoleptic ([PbL2]) and/or heteroleptic ([Pb(OAc)L]) complexes containing deprotonated pyrazolones L− formed by metal-induced cyclization of the starting HTSC ligands. All the complexes isolated were characterized by IR spectroscopy in the solid state and by 1H and 13C NMR spectroscopy in DMSO solution; in addition, crystals containing [Pb(L6)2] and [Pb(L7)2] were examined by X-ray crystallography. [Pb(L6)2]·0.5H2O·0.3MeOH (HL6 =4-ethyl-2,5-dihydro-3-methyl-5-oxo-1H-pyrazole-1-carbothiamide) showed three types of molecule with significant structural differences that appear to be determined by packing interactions. In all three molecules the Pb⋯Pb distances are very short [3.6096(8)–3.7562(8)Å], but density-functional-theoretic calculations at the B3LYP level do not support the existence of Pb–Pb bonds. In [Pb(L7)2] (HL7 = N-ethyl-2,5-dihydro-3-methyl-5-oxo-1H-pyrazole-1-carbothiamide) all the molecules are of a single type, and they are linked in a three-dimensional network by weak intermolecular Pb⋯O bonds. [Copyright &y& Elsevier]

Abstract: The reaction of oxythiamine chloride hydrochloride (HOxTCl·HCl) with ZnCl2, CdCl2 and HgCl2 in ethanol yielded the complexes [ZnCl3(HOxT)], [CdCl3(HOxT)] and [HgCl3(HOxT)]. In water, the reaction with CdCl2 afforded [CdCl2(OxT)], but reaction with ZnCl2 or HgCl2 yielded unidentified products. The four new complexes were characterized by mass spectrometry and IR spectroscopy in the solid state and by 1H, 13C and 15N nuclear magnetic resonance (NMR) spectroscopy in hexadeuterated dimethylsulfoxide (DMSO-d 6), and three were also studied by X-ray diffractometry. In [ZnCl3(HOxT)] and [HgCl3(HOxT)] the oxythiamine ligand is bound to the metal via N(1′) and adopts the V conformation exhibited by thiamine in biological contexts. The infrared (IR) spectrum of [CdCl3(HOxT)] suggests a similar coordination mode. In [CdCl2(OxT)] each OxT zwitterion coordinates to one Cd(II) ion via its N(1′) atom and to another via its N(3′) and O atoms, giving rise to a polymeric chain along the x-axis. The coordination number of the metal is made up to six by Cd⋯Cl interactions, two of which link the polymeric chains in pairs. This seems to be the first metal complex containing the oxythiamine ligand as a zwitterion, with the N(3′)–H/O(4′α)–H group deprotonated. Neither HOxTCl nor its zinc(II) complex showed any significant activity in vitro against HeLa cells. [Copyright &y& Elsevier]

The reactions of Me(Ph)SnCl2 and Et(Ph)SnCl2 with 2,6-diacetylpyridine bis(thiosemicarbazone) (H2DAPTSC) afforded the complexes [Me(Ph)Sn(HDAPTSC)]Cl · 1.25MeOH (1) and [Et(Ph)Sn(H2DAPTSC)]Cl2 · MeOH · H2O (2), respectively. Single-crystal X-ray crystallography showed that in both complexes the ligand, monodeprotonated in 1 and neutral in 2, is S(1),S(2),N(3),N(4),N(5)-coordinated, and the coordination geometry around the metal can be described as a distorted pentagonal bipyramid with the aryl and alkyl groups in axial positions. 1H and 119Sn NMR studies of solution in DMSO suggest that 2 dissociates completely in this solvent, while 1 evolves to the new complex [Me(Ph)Sn(DAPTSC)], with release of H2DAPTSC and Me(Ph)SnCl2. These conclusions were also supported by conductivity measurements. Complexes of R(Ph)SnCl2 (R=Me, Et) with 2,6-diacetylpyridine bis(thiosemicarbazone) have been synthesized and characterized by X-ray crystallography, 1H and 119Sn NMR spectroscopy and conductivity measurements. The crystal structures of [Me(Ph)Sn(HDAPTSC)]Cl · 1.25MeOH (1) and [Et(Ph)Sn(H2DAPTSC)]Cl2 · MeOH · H2O (2) contain the ligand, monodeprotonated or neutral, acting as pentadentate. NMR studies in DMSO solution suggest the total dissociation of (2), whereas (1) evolves to form the new complex [Me(Ph)Sn(DAPTSC)]. [Copyright &y& Elsevier]

The crystal structure of [Ru(NH3)5(OH2)]2(S2O6)3 · 2H2O has been solved by X-ray diffraction techniques. The relevant average interatomic distances are Ru–(NH3)eq=2.09 A˚, Ru–(NH3)ax=2.08 A˚ and Ru–(OH2)ax=2.11 A˚. The aquation rate (kH2O) and the activation parameters for the reactiontrans-[RuNO(NH3)4Cl]2++H2O→, upper limit kH2O trans-[RuNO(NH3)4(H2O)]3++Cl−have been calculated as 8.4 × 10−6 s−1 (0.10 mol L−1 CF3COOH, μ=0.10 mol L−1, 40 °C), ΔH≠−1=2.3 kcal mol−1, ΔS≠−1=24.0 cal deg−1 mol and ΔG≠−1=8.6 kcal mol−1. A comparison between the structural data, kinetic and thermodynamic reactivities of [Ru(NH3)5(OH2)]3+ and trans-[RuNO(NH3)4(OH2)]3+ ions strongly suggests that the substitution of the trans NH3 ligand in the coordination sphere of [Ru(NH3)5(OH2)]2+ by NO confers a character of Ru(III) to the formally Ru(II) center. [Copyright &y& Elsevier]

Methylmercury(II) xanthates, MeHgS(S)COR, with R=Et, iPr and CH2Ph, form unidimensional, supramolecular self-assembled, tape-like arrays in the solid state, based upon Hg⋯S intermolecular secondary interactions. In the compounds with R=Et and iPr the individual molecules form double chains (tapes) weakly interacting with neighbouring arrays, while the compound with R=CH2Ph forms dimeric units, which are further associated into infinite tapes, not interacting with each other. Primary Hg&z.sbnd;S bonds are in the range 2.378(5)–2.391(3) A˚, intramolecular Hg⋯S secondary bonds leading to chelation are in the range 3.179(5)–3.259(3) A˚, whereas intermolecular Hg⋯S secondary interactions cover a broader range, from 3.403(4) to 4.22(1) A˚. [Copyright &y& Elsevier]