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EN
The complexes of Co(II), Ni(II) and Cu(II) with 3-hydroxysalicyliden-p-aminoacetophenoneoxime were prepared and characterized by physical, spectral and analytical data. The metal:ligand stoichiometric ratio is 1:2 in all the complexes. It was determined that the bidentate behavior of the ligand is accomplished via the phenolic oxygen and the azomethine nitrogen atoms. The presence of water is revealed by thermograms and supported by the presence of relevant bands in their IR spectra. Suitable structures have been proposed for these complexes.
EN
A novel vic-dioxime ligand (LH4) and its transition metal complexes with Cu(AcO)2×H2O, Ni(AcO)2×4H2O, Co(AcO)2×4H2O and Cd(AcO)2 metal salts were synthesized. 1,2-Bis(p-aminophenoxy)ethane reacted with anti-chloroglyoxime to give N,N'-[4,4'-{ethane-1,2-di-yl-bis(oxy)bis(4,1-phenylene)}bis(N-hydroxy)2-(hydro -xyimino)acetimidamide] (LH4) ligand. Ligand forms binuclear complexes [(LH3)2M2(AcO)2]×nH2O with a 2:2 metal to ligand ratio, where M = Cu(II), Ni(II) and Cd(II), n = 2, 2 and 1, respectively. LH4 forms also binuclear Co(II) complex [(LH4)2Co2(AcO)4(H2O)2]ź2H2O with a metal to ligand ratio of 2:2. The Ni(II) and Cd(II) complexes are proposed to be tetrahedral while the Cu(II) and Co(II) complexes should be octahedral. Structural assignments are supported by a combination of elemental analyses, UV-Vis, IR and 1H-NMR spectra, magnetic measurements and TGA and DTA techniques.
EN
34-membered macrocyclic hexaamine containing two independent N-3 donor sets forms homodinuclear transition metal complexes with cobalt(II), copper(II), and nickel(II). Titration experiments show that the homodinuclear complexes are formed exclusively without formation of mononuclear complexes. Displacements of anions within the copper(II) complexes occur easily upon addition of different anions to the CuCl2 complex. All new complexes are characterized by elemental analysis, IR and UV/VIS spectroscopy, and cyclic voltammetry. The dinuclear Cu(II) complex both in the solution and immobilized in Nafion layer on the electrode undergoes revesible l e reduction independently at each copper center and exhibits catalytic activity towards oxygen reduction.
EN
The present paper details the synthesis of new explosive complexes of the DDT type and the investigation of their sensitiveness to friction and impact. Fourteen new compounds, specifically nitrate and perchlorate complexes of various transition block metals with 5-(2,4,6-trinitrophenylamino)tetrazole, commonly called picrylaminotetrazole (PAT), were synthesised. The nitrate complexes were obtained in yields varying between 8.1% and 75.1%, whereas the perchlorate complexes had yields between 24.9% and 67.3%, with yields typically near the upper bound of the given ranges for both classes of complexes and the low yields obtained for [Co(PAT)3](NO3)3 and [Cd(PAT)3](ClO4)3 being the exception rather than the rule. The structures of these compounds were unambiguously established via XRF and IR spectroscopy, as well as via elemental analysis. Detailed analyses of the safety properties of these new materials were performed in terms of their sensitiveness to friction and impact. In general, the obtained compounds present relatively low sensitivity to mechanical stimuli, like friction and impact, with the nitrate complexes of Ni and Zn exhibiting high sensitivity to impact (1-2 Nm). The rest of the investigated compounds show low sensitivity to mechanical stimuli, comparable to classical blasting materials like PETN, RDX or HMX. It should be noted that, in general, the nitrates were more sensitive to mechanical stimuli than their perchlorate analogues.
EN
A straightforward and versatile method for the determination of the absolute configuration of vic-diols is presented. The proposed method involves the in situ formation of chiral complexes of optically active vic-diols with the achiral dimolybdenum tetraacetate [Mo2(OAc)4] acting as an auxiliary chromophore. The resulting CD spectra are suitable for the assignment of absolute configuration, since the observed sign of Cotton effects arising within the d-d absorption bands of the metal cluster depends solely upon the chirality of the 1,2-diol ligands.An empirically based rule correlating a positive/negative helicity expressed by the O-C-C-O torsional angle with the sign of Cotton effects occurring in the 400-280 nm spectral range has been presented. The applicability of the rule is extended to sterically hindered sec/tert vic-diols.
EN
Complexes of Co(II), Ni(II) and Cu(II) with 1-(2'-hydroxy-3'- iodo-5'- methylphenyl)- 3-(3,4-methylenedioxyphenyl)-2-propen-1-one (L1), 1-(2'- hydroxy-3'-bromo-5'- chlorophenyl)- 3-(3,4- methylenedioxyphenyl)-2-propen-1-one (L2) and 1-(2'- hydroxy-3'-iodo- 4'-methyl-5'-chlorophenyl)-3- (3,4-methylene dioxyphenyl)-2- propen-1- one (L3) have been prepared and characterized with the help of elemental analyses, molar conductivity, magnetic measurement, electronic spectra, infrared spectra, ESR and thermal analysis. Elemental analyses confirmed a 1:2 (metal:ligand) stoichiometry. The conductivity data show that all these complexes are non-electrolytes. The infrared spectral data indicate that the L1, L2 and L3 act as mononegative bidentate ligands with all the metal ions and the electronic spectral data suggest that all Co(II), Ni(II) complexes have pseudooctahedral geometry whereas Cu(II) complexes have square planar geometry. Presence of coorinated water molecules in Co(II), and Ni(II) complexes is confirmed by TGA studies. ESR parameters of Cu(II) complexes have been calculated and relevant conclusions have been drawn with respect to the nature of bonds present in them.
EN
A series of new coordination complexes in volving chromium(III), manganese(III), iron(III) and cobalt(III) with Schiff bases derived from condensation of o-vanillin with diamines viz. 1,2-diaminoethane, 1,3-diaminopropane, 1,4-diaminobutane or 1,2-dia - minobenzene and monoamines viz., p-methylaniline or p-methoxyaniline have been prepared and characterized by elmental analysis, spectral (IR, electronic, 1H NMR, FAB mass), magnetic susceptibility and electrical conductance measurements. The IR spectra suggest that o-VDAEH2, o-VDAPH2, o-VDABuH2 and o-VDABH2 are dibasic tetradentate ligands to wards all the four metals giving the complexes with composition [M(L)(H2O)X] (X = Cl, and OAc; LH2 = o-VDAEH2, o-VDAPH2, o-VDABuH2 and o-VDABH2) while o-VPMEAH and o-VPMAH are monobasic bidentate ligands towards the metals giving the complexes with composition [M(Lc)3] (LcH = o-VPMEAH and o-VPMAH). Various physicochemical data suggest a six coordinated octahedral geometry for all the complexes. Studies were conducted to investigate the inhibiting potential of the complexes synthesized and the ligands, against various fungal and bacterial strains.
EN
A new series of chloride transition metal complexes containing a diethyl (pyridyn-2-ylmethyl) phosphate (2-pmOpe) ligand, of the general formula [M(2-pmOpe)2Cl2] (M = Cu, Ni, Mn) and [M(2-pmOpe)Cl2] (M = Co, Zn), were synthesized and studied. The stoichiometry and stereochemistry of the compounds were confirmed by elemental analysis, spectroscopic and magnetic studies. The ligand containing two donor atoms, heterocyclic pyridyl nitrogen and phosphoryl oxygen atoms, binds in a didentate chelate manner in all complexes. The octahedral (Cu, Ni, Mn) and tetrahedral (Co, Zn) coordination sphere complete chloride ions included in coordination. The magnetic behaviour (for paramagnetic centres) and spectroscopic analyses of the complexes indicate a mononuclear structure and suggest existence of a very weak exchange coupling between the metal centres in the crystal lattice.
9
Content available remote Sililenowe kompleksy metali przejściowych
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EN
Major advance in organometallic chemistry in the last 15 years has been achieved in the area of silicometallics chemistry, based on silicon to metal multiple bonding and silicon with low coordination numbers. Research in this area has led to a discovery of fundamentally new classes of compounds, such as silylene, silene, silaimine, disilene or silacarbyne complexes. Many of these systems had been unknown prior to their synthesis, even as reactive intermediates. This paper provides a comprehensive review of the silylene transition metal complexes. The majority of metal - silylene complexes synthesised so far have required donor stabilisation via the addition of a Lewis base. The use of thermally stable bis(amino)silylenes as ligands has led to a synthesis of base-free, stable silylene metal complexes. The chemistry of these compounds is discussed under headings: types of silylene complexes, methods of their synthesis, structure and properties of TM silylene complexes and also their application to catalysis. Despite the fact that the stable silylene transition metal complexes have been known for less than a decade, the chemistry of these compounds has been comprehensively recognised.
EN
Optically active carboxylic acids can act as uni- or bidentante ligands in complexes of general formula [M2(O2CR)4] +k X-k (M = Mo, Rh or Ru). An in situ exchange of ligand(s) gives rise to several Cotton effects in the spectral range from 800 to 200 nm. In the case of molybdenum complexes with optically active hydroxy and amino acids a hexadecant rule is valid for the two Cotton effects between 400 and 300 nm. For rhodium and ruthenium complexes it was found that the sign of Cotton effects at around 600 nm can be correlated with the structure of investigated acids.
EN
A new series of nitrate transition metal complexes containing diethyl(pyridin-3-ylmethyl)phosphonate (3-pmpe) as a ligand, having a general formula [M(3-pmpe)2(H2O)2](NO3)2 (M = Cu, Co and Ni) and [Zn(3-pmpe)2](NO3)2 were prepared. The complexes were identified and characterized by the elemental analysis, spectroscopic and magnetic studies. Ligands containing two donor atoms, heterocyclic nitrogen and phosphoryl oxygen atoms bind in a bidentate bridging manner via the pyridine nitrogen and the phosphoryl oxygen atoms. The magnetic behaviour in the temperature range 1.8-300 K) of the Cu(II), Ni(II), Co(II) complexes as well as their spectroscopic properties suggest polymeric structure of all complexes and the existence of a weak antiferromagnetic exchange coupling between paramagnetic centres inside the dibridged linear chains [M(3-pmpe)2M]n.
EN
Two polyaromatic acid transition metal complexes: {[Cd(phen)(O2C)2C4N2H2]źH2O}n (1), and {[Mn(phen)(O2C)2C4N2H2]źH2O}n (2) (phen = 1,10-phenanthroline) have been hydrothermally synthesized and characterized by elemental analyses, IR spectroscopy, and single-crystal X-ray diffraction. The structural analysis reveals that compound 1 and compound 2 are almost isostructural. The metal atoms are linked by bridging 2,3-di -carboxylatopyrazine ligands to form 2-D layer network, and have a coordination number six.
EN
Extraction of complexes of 1,2-dimethylimidazole, 1-ethyl-2-methylimidazole, 1-propyl-2-methylimidazole and 1-butyl-2-methylimidazole with Co(II), Ni(ii0, Cu(II), Zn(II) and Cd(II) from aqueous solutions (I=0.5 at 298 K) with benzyl alcohol was investigated. For each system, the composition of the extracted species, their partition constans and the pH1/2 were determined.
EN
Four novel Knoevenagel type Cu(II), Ni(II), Co(II) and Zn(II) macrocyclic complexes derived from 3-cinnamalideneacetoacetanilide and N-(2-aminoethyl)-1,3-propanediamine have been synthesized. The nature of complexes and the geometry have been inferred from their microanalytical data, magnetic susceptibility measurements, IR, UV-Vis., 1H NMR, ESR and mass spectral techniques. The low electrical conductance of complexes supports their neutral nature.Monomeric nature of the complexes is assessed from theirmagnetic susceptibility values. The in vitro biological screening effects of the investigated compounds were tested against the bacteria E. coli, S. aureus, S. typhi and K. pneumoniae by the well diffusion method using agar nutrient as the medium. A comparative study of MIC values of the macrocyclic Schiff base ligand and its complexes indicates that the complexes exhibit higher antibacterial activity than the free ligand. The cyclic voltammetry method was used to probe the interaction of a Cu(II) complex with pUC18 DNA. Information of the binding ratio and intercalation mode can be obtained from its electrochemical data. Cyclic voltammetric measurements showed that Cu(II) complex undergoes a reversible reduction at biologically accessible potentials. From the study, it is understood that copper complex prefers to bind with DNAin Cu(II) rather than Cu(I) oxidation state. The DNAcleavage ability of the complexes was monitored by gel electrophoresis using super coiled pUC18 DNA in Tris-HCl buffer.
EN
The compounds of general formula [ML2](ClO4)2 [M = Cu(II), Ni(II), Co(II)]; L = diethyl 3-pyridylmethyl[N-(butyl)amino]phosphonate (3-pmape) or diethyl 4-pyridylmethyl[N-(butyl)amino]phosphonate (4-pmape) were prepared. The new complexes were identified and characterized by elemental analysis, infrared, electronic spectral studies and magnetic measurements. The complexes are sixcoordinate. Metal ions are octahedrally surrounded by two pyridine and two amine nitrogens, and two oxygens of the phosphoryl groups. The results of the magnetic studies suggest polymeric chain structure of the above complexes and indicate weak antiferromagnetic interaction between the magnetic centers. The magnetic behavior of Co(II) complexes is characteristic for cobalt(II) system with an important orbital contribution via spin-orbit coupling.
EN
The new ligand salicyliden-p-aminoacetophenoneoxime (LH) was synthesized from p-aminoacetophenoneoxime and salicylaldehyde under reflux in absolute ethanol. Mononuclear complexes with a metal:ligand ratio of 1:2 have been prepared with Co2+, Ni2+, Cu2+ and Zn2+ salts. Their structures have been elucidated on the basis of IR, 1H- and 13C-NMR spectra, electronic spectra, elemental analyses, magnetic susceptibility measurements, molar conductivity and thermogravimetric analyses. According to the results, it is suggested that two ligands are coordinated to each metal atom by hydroxyl and the imino nitrogen to form high spin tetrahedral complexes with Co2+, Ni2+, Cu2+ and diamagnetic complex with Zn2+.
EN
A new series of the chloride and nitrate transition metal complexes containing the ligand diethyl 2-quinolylmethylphosphonate (2-qmpe) of general formula M(2-qmpe)(NO3)2 (M = Cu, Co), [Zn(2-qmpe)(H2O)2NO3]NO3ź H2O, [Ni(2-qmpe)(H2O)2NO3]NO3, M(2-qmpe)2Cl2 (M = Cu, Ni, Co, Pd) and M(2-qmpe)Cl2 (M = Co, Zn) were prepared. The complexes were identified and characterized by elemental analysis, spectroscopic and magnetic studies. Ligand containing two donor atoms, heterocyclic nitrogen and phosphoryl oxygen atoms exhibits different coordination properties. It was shown that the ligand binds in a bidentate chelate manner via the quinoline nitrogen and the phosphoryl oxygen atoms (complexes with 1:1 metal to ligand molar ratio) and it can also acts as a monodentate ligand coordinated through the nitrogen in the Pd(II) or oxygen atom in the Cu(II) and Co(II) complexes (complexes with 1:2 metal to ligand molar ratio). The magnetic behaviour of the Cu(II), Ni(II) and Co(II) and spectroscopic investigation of Zn(II) complexes suggests mononuclear structure of all the complexes and the existence of a weak intermolecular exchange coupling between magnetic centres inside crystal lattice.
18
Content available remote TLC study of the separation of the enantiomers of lactic acid
80%
EN
Enantiomer separation by TLC is still much less frequent than with other, mostly instrumental, chromatographic techniques. From a literature survey it is apparent that separation of the enantiomers of D,L -lactic acid is primarily of interest to the diary industry and that this particular separation is less frequently performed by chromatographic than by membrane techniques. As far as we are aware, before our studies only one report of TLC separation of the enantiomers of D,L -lactic acid was available in the literature; this is dated 1991 and describes the use of non-instrumental TLC only. In this study, we started by reproducing the TLC procedure originating from 1991, for this purpose using TLC with automatic sample application and densitometric detection. We managed to repeat the earlier procedure and to achieve full, i.e. baseline, separation of the enantiomers, with a remarkable distance between the two antimers. However, we revealed a significant drawback of this separation procedure - D -(-)-lactic acid was transported almost with the mobile-phase front and its densitometric quantification was barely possible because of the relatively high UV absorption of the mobile-phase front line. The reference method for separation of the enantiomers of D,L -lactic acid consisted in preliminary impregnation of commercial silica gel TLC plates with copper(II) acetate. In-situ formation of bidentate complexes of the D,L -lactic acid antimers with the Cu 2+ cation resulted in different mobilities of these complex cations in the planar chromatographic system. The objectives of this study were twofold - to investigate separation of the enantiomers of D,L -lactic acid with other transition metal cations (i.e., Co 2+, Ni 2+, and Mn 2+) used to impregnate the silica gel (to achieve resolution that might enable quantification of the two lactic acid antimers and not only the L -(+) enantiomer) and to gain deeper insight into the mechanism of separation with these metal cations. For purposes of comparison, we chromatographed D,L -lactic acid on non-impregnated silica gel layers. As a result, we managed to establish efficient separation conditions with the Ni 2+ and Co 2+ cations that outperformed the earlier established procedure involving the Cu 2+ cation, and - partially at least - to elucidate the mechanism of separation of the enantiomers of D,L -lactic acid by these TLC systems. The Mn 2+ cation proved unsuitable for the purpose. Finally, we managed to separate the enantiomers of D, L -lactic acid on non-impregnated silica gel layer also, which seems yet more proof of the microcrystalline chirality of silica gel used as stationary phase and of its substantial contribution to the enantiomer separation investigated.
EN
A new ligand including vic-dioxime moiety, 9,10-bis(hydroxyimino)-4,8,11,15-tetraaza- 1,2,17,18-O-di_-methylbenzaloctadecane (LH2) has been synthesized and its mononuclear complexes have been prepared. LH2 forms transition metal complexes [(LH)2M] with a metal:ligand ratio of 1:2 with M = Co(II)(H2O)2, Ni(II) and Cu(II). Zn(II) forms with H2L complex [Zn(LH2)(Cl)2], which has a metal:ligand ratio of 1:1. The mononuclear Co(II), Ni(II), Cu(II) and Zn(II) complexes indicated that the metal ions are ligand coordinated through the twoNatoms, as do most of the vic-dioximes. In the Co(II) complex two water molecules and in the Zn(II) complex two chloride ions are also coordinated to the metal ion. Elemental analyses, IR, 1H- and 13C-NMR spectra, UV-Visible spectroscopy, magnetic susceptibility measurements, conductivity measurements and thermogravimetric analyses (TGA) were used to elucidate the structures of the newly prepared ligand and its complexes. These results indicate octahedral geometry for the Co(II) complex, square planar geometry for the Ni(II) and Cu(II) complexes, tetrahedral geometry for the Zn(II) complex.
EN
In order to find out whether metal type influences the stacking interactions of phenyl rings in square-planar complexes, geometrical parameters for Cu, Ni, Pd and Pt complexes, with and without chelate rings, were analyzed and compared. By searching the Cambridge Structural Database, 220 structures with Cu complexes, 211 with Ni complexes, 285 with Pd complexes, and 220 with Pt complexes were found. The results show that the chelate ring has a tendency to make the stacking interaction with the phenyl ring independent of metal type in the chelate ring. However, there are some differences among metals for complexes without a chelate ring. There are a number of structures containing Pd and Pt complexes, without chelate rings, that have short carbon-metal distances and parallel orientations of the phenyl ring with respect to the coordination plane. It was found that some of these complexes have a common fragment, CN, as a part of the ligands. This indicates that the CN supports stacking interactions of square planar complexes with the phenyl ring. [...]
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