Ternary complexes of cimetidine and phenobarbital with Cu(II) in methanolic solution

The formation constants of the binary complexes Cu(CM)²⁺ and Cu(CM) ₂ ²⁺ as well as those of the ternary complexes Cu(CM)L ⁺ and Cu(CM)₂ L ⁺ (CM=Cimetidine=N-Cyano-N-methyl-N[(5-methyl-1H-imidazol-4-yl)methyltioethyl]-guanidine; HL=Phenobarbital=5-ethyl-5-phenyl-barbituric acid) have been determined in 0.1 and 1.0 mol dm^–3 NaClO₄ methanol solutions at 25±0.2°C. The values of logX, log _stat.., and logK confirm the stability of the ternary complexes.

---

Ternäre Komplexe von Cimetidin und Phenobarbital mit Cu(II) in methanolischer Lösung

Zusammenfassung Die Stabilitätskonstanten der binären Komplexe Cu(CM)²⁺ und Cu(CM) ₂ ²⁺ sowie die der ternären Komplexe Cu(CM)L ⁺ und Cu(CM)₂ L ⁺ (CM=Cimetidin=N-Cyan-N-methyl-N-[(5-methyl-1H-imidazol-4-yl)methylthioethyl]-guanidin; HL=Phenobarbitalum=5-Ethyl-5-phenyl-barbitursäure) wurden in 0.1 und 1.0M Lösungen von NaClO₄ in Methanol bei 25±0.2°C bestimmt. Die Werte von logX, log _stat. und logK bestätigen die Stabilität der ternären Komplexe.

     

Photooxidation of bis(ethylxanthato)nickel(II) containing aromatic nitrogen heterocyclic ligands in chloroform

The photochemistry of the complexes [Ni(Etxn)₂(N-N)] [Etxn=ethylxanthate,N-N=2,2-bipyridine(bpy), 4,4-dimethyl-2,2-bipyridine (4,4-Me-bpy), 1,10-phenanthroline (phen) or 2,2-bipyrimidine (bpym)] has been investigated. These complexes were not light sensitive in most solvents such as acetonitrile. Upon irradiation of chloroform solutions of these complexes, a photoredox reaction occurred giving the parent Ni(Etxan)₂. It is suggested that the reactive excited state is of the charge-transfer-to-solvent (CTTS) type. The energy of this state depends on the redox potentials of the solvent. When CHCl₃ as solvent was replaced by the stronger oxidant CCl₄, the photoactive wavelength region was shifted to the red. It was blue shifted when the weaker oxidant CH₂Cl₂ was used. From quantum yield measurements it is concluded that the photostability of the studied complexes decreases in the following order:bpym>phen>bpy>4,4-Me-bpy.

---

Photooxidation von Bis(ethylxanthato)nickel(II) mit aromatischen Stickstoffheterocyclen enthaltenden Liganden in Chloroform

Zusammenfassung Es wurde die Photochemie der Komplexe [Ni(Etxn)₂(N-N) [Etxn=Ethylxanthat,N-N=2,2-Bipyridin (bpy), 4,4-Dimethyl-2,2-bipyridin (4,4-Me-bpy), 1,10-Phenanthrolin (phen) oder 2,2-bipyrimidin (bpym)] untersucht. Diese Komplexe waren in den meisten Lösungsmitteln wie etwa Acetonitril nicht lichtsensitiv. Bei Bestrahlung von Chloroformlösungen der Komplexe trat jedoch eine Photoreaktion auf, die zum Stammkomplex Ni(Etxn)₂ führte. Es wird vorgeschlagen, für den reaktiven angeregten Zustand einen Charge-Transfer-zu-Lösungsmittel (CTTS)-Typ anzunehmen. Die Energie dieses Zustands hängt vom Redoxpotential des Lösungsmittels ab. Bei Ersatz von CHCl₃ als Lösungsmittel durch das stärkere Oxidans CCl₄ wurde die photoaktive Wellenlänge nach Rot verschoben. Eine Blauverschiebung ergab sich hingegen, wenn das schwächere Oxidans CH₂Cl₂ verwendet wurde. Aus Messungen der Quantenausbeuten ergab sich die folgende Ordnung nach abnehmender Photostabilität der untersuchten Komplexe:bpym>phen>bpy>4,4-Me-bpy.

     

Gold(I) Pyrazolate Clusters: The Structure and Luminescence of the Tetranuclear, Base-Stabilized [(dppm)2Au4(3,5-Ph2Pz)2](NO3)2 ⋅ H2O

The tetranuclear Au(I) pyrazolate complex, [(dppm)₂Au₄(3,5-Ph₂Pz)₂](NO₃)₂  H₂O, 1, has been synthesized and structurally characterized. It is the first tetranuclear pyrazolate of Au(I) to have been found, although the trinuclear pyrazolates of Au(I) are well known. Complex 1 exhibits luminescence at 77 K when excited at 333 nm with an emission maximum at 454 nm. The emission has been assigned to ligand to metal charge transfer, LMCT, based upon the vibronic structure that is observed. The complex crystallizes in the monoclinic space group P2₁/c, with a=19.33(3) Å, b=20.26(3) Å, c=19.80(3) Å, =106.74(2)°, V=7425(17) ų, Z=8, and R=0.058. The Au    Au distances are Au(1)    Au(4)=3.185(3) Å, Au(1)    Au(2)=3.230(3) Å, Au(2)    Au(3)=3.079(3) Å, and Au(3)    Au(4)=3.280(3) Å.     

Thermal Decomposition Kinetics of the Zn(II) Complex with Norfloxacin in Static Air Atmosphere

The thermal decomposition of Zn[NFA]₂5H₂O (NFA=C₁₆H₁₈FN₃O₃, norfloxacin) and its kinetics were studied under non-isothermal conditions in air by TG-DTG and DTA methods. The intermediate and residue for each decomposition were identified from the TG curve. The non-isothermal kinetic data were analyzed by means of the Achar method and the Madhusudanan-Krishnan-Ninan (MKN) method. The possible reaction mechanisms were investigated by comparing the kinetic parameters. The kinetic equation for the second stage can be expressed as d/dt=Aexp(–E/RT)(1–).This revised version was published online in November 2005 with corrections to the Cover Date.     

Characteristic of the Ag(II)/Ag(I) system in the presence of 2,2′:6′,2″-terpyridine in acetonitrile

Summary Composition of complexes of Ag(II) and Ag(I) ions with 2,2:6,2-terpyridine (tp) have been established. It has been found that the Ag⁺ ion forms only one complex Ag(tp)⁺ withtp in acetonitrile; its conditional formation constant: ₀₁=6.6·10⁴ has been determined by the potentiometric method. Equilibria and redox systems formed in solutions due to the complexation of Ag⁺ and Ag²⁺ and oxidation of Ag(II) complexes are described. Their formal potentials have been found by coulometric and voltamperometric examinations. The presence of the Ag(tp) ₂ ³⁺ ion in the anodic oxidized solutions of the complexes Ag(tp)(NO₃)₂ and Ag(tp)₂(NO₃)₂ has been proved. Properties of the system Ag(II)/Ag(I) in the presence of terpyridine in water and in acetonitrile have been compared.

---

Charakteristik der Systeme Ag(II)/Ag(I) in Gegenwart von 2,2:6,2-Terpyridin in Acetonitril

Zusammenfassung Die Zusammensetzung der Komplexe von Ag(I)- und Ag(II)-Ionen mit 2,2:6,2-Terpyridin (tp) wurde bestimmt. Das Ag⁺-Ion bildet mittp in Acetonitril nur einen Komplex-Ag(tp)⁺. Seine Konditionalbildungskonstante ₀₁=6.6·10⁴ wurde mit Hilfe der potentiometrischen Methode bestimmt. Es wurden die Gleichgewichte und Redoxsysteme als Resultat der Komplexbildung von Ag(II)- und Ag(I)-Ionen und der Ag(II)-Komplexoxidation charakterisiert und die Formalpotentiale mittels Voltametrie und Coulometrie bestimmt. Die Gegenwart der Ag(tp) ₂ ³⁺ -Ionen wurde in anodisch oxydierten Lösungen der Komplexe Ag(tp)(NO₃)₂ und Ag(tp)₂(NO₃)₂ nachgewiesen. Die Eigenschaften des Systems Ag(II)/Ag(I) in Gegenwart von 2,2:6,2-Terpyridin in Wasser und in Acetonitril wurden verglichen.

     

Synthesis and X-ray structures of dinitrato-bis[2-(2′-thienyl)-1-(2′-thienylmethyl)benzimidazole]copper(II) and dichloro-bis-[2-(2′-thienyl)-benzimidazole]copper(II)-ethanol

Summary The reactions of Cu(NO₃)₂ · 3 H₂O with 2- (2-thienyl)-1-(2-thienylmethyl)benzimidazole (L) and of CuCl₂ · 2H₂O with 2-(2-thienyl)benzimidazole (L) have been carried out. The crystal structure of two isolated complexes,(1) and(2), have been determined by single-crystal x-ray diffraction methods. Crystals of(1) are monoclinic, space groupP2₁ /c, witha=9.884(4),b=9.892(4),c=18.732(8) Å, =114.89(2)°,Z=2;R=0.068 for 1909 observed reflections. Crystals of (2) are orthorhombic, space groupPbcn, witha=14.835(1),b=8.193(1),c=20.493(1) Å,Z=4;R=0.086 for 415 observed reflections. In the complex (1) the copper co-ordination is tetragonal (compressed octahedral) and involves a nitrogen atom of the organic ligand [Cu-N 1.970(6) Å] and two oxygen atoms of the nitrate group [Cu-O 2.318(7) and 2.246(9) Å] which appears to coordinate nearly symmetrically to the metal; however it has unusually large thermal motion which suggests a fluxional behaviour. In the complex (2) the co-ordination is square planar and involves an imidazole nitrogen [Cu-N 1.95(3) Å] and a chlorine atom [Cu-Cl 2.27(1) Å]. A long interaction Cu-S=3.37(2) Å completes the co-ordination polyhedron to a very elongated distorted tetragonal bipyramid. In both compounds a thiophene ring is disordered.     

Polarographic study of composition and stability constants of Pb(II) N-(2-acetamido) imino diacetate complexes

Summary The complexation of Pb(II) by N-(2-acetamido) imino diacetate (ADA) has been studied polarographically (dc and ac polarographic techniques). Ac polarographic studies have been particularly helpful in deciding the reversibility of the reduction of both simple and complexed metal ions and for confirmation of the overall stability constants. A weighted least squares numerical technique has been applied for the calculation of the overall stability constants using both dc and ac techniques. The reduction of Pb(II) in N-(2-acetamido) iminodiacetate solutions has been found to be reversible and diffusion controlled, involving a two electron transfer process. Potential vs. concentration data at =0.1 mol dm^–3 (KNO₃) are interpreted on the basis of the formation of two complex species PbADA and Pb(ADA)^2– in thepH range 6.85–8.50. The logarithms of the stability constants (calculated from ac measurements) of these complexes are 8.73±0.12, 10.86±0.18 at 25°C, 8.31±0.28, 10.31±0.09 at 35°C and 7.61±0.20, 10.10±0.11 at 45°C, respectively. The thermodynamic parameters G, H and S have been calculated at 35°C.

---

Polarographische Untersuchung von Zusammensetzung und Stabilitätskonstanten von Pb(II) N-(2-Acetamido)iminodiacetat-Komplexen

Zusammenfassung Es wurde die Komplexierung von Pb(II) mit N-(2-Acetamido)iminodiacetat (ADA) polarographisch mittels DC- und AC-Techniken untersucht. Insbesonders AC-Polarographie ergab eine klare Entscheidung bezüglich der Reversibilität der Reduktion von einfachen und komplexierten Metallionen und für die Bestätigung der Stabilitätskonstanten. Zur Bestimmung der Gesamtstabilitätskonstanten wurde eine gewichtete mittlere Fehlerquadrat-Methode auf Basis von DC- und AC-Messungen herangezogen. Die Reduktion von Pb(II) in N-(2-Acetamido)iminodiacetat-Lösung stellte sich als ein reversibler und diffusionskontrollierter Zweielektronen-Transferprozess heraus. Die Abhängigkeit des Potentials von der Konzentration bei =0.1 mol dm^–3 (KNO₃) läßt sich mit der Bildung von zwei Komplex-Spezies PbADA und Pb(ADA)^2– impH-Bereich 6.85–8.50 erklären. Die Logarithmen der Stabilitätskonstanten dieser Komplexe (aus AC-Messungen) sind 8.73±0.12 und 10.86±0.18 bei 25°C, 8.3 ±0.28 und 10.31±0.09 bei 35°C bzw. 7.61±0.20 und 10.10±0.11 bei 45°C. Die thermodynamischen Parameter G, H und S wurden für eine Temperatur von 35°C berechnet.

     

1D and 2D Systems Derived from Polynuclear [ ML(N 3) 2] n ( M?=?Zn(II) or Cd(II) and L is 2-Picoline- N-oxide or 4-Methylpyrimidine)

Summary. Four new polynuclear complexes: [Zn(2picNO)(N₃)₂]_n, [Zn(4Mepym)(N₃)₂]_n, [Cd(2picNO)(N₃)₂]_n, and [Cd(4Mepym)(N₃)₂]_n (2picNO=2-picoline-N-oxide and 4Mepym=4-methylpyrimidine) have been synthesized and characterized by single-crystal X-ray diffraction. The structures of the zinc(II) complexes feature five-coordinate zinc atoms, (-1,1) azido bridges, monodentate organic ligands, and 1D chains. The cadmium(II) azide complexes contain distorted octahedral metal atoms linked by alternate di-(-1,1) and di-(-1,3) azido bridges in cis arrangement and these chains are connected by 2picNO bridges giving a honeycomb 2D framework or by 4Mepym bridges forming extended 2D network structure.     

Synthesis and structure of [(OC)4Os(PbMe2)]2 and some derivatives of the type Os2(CO)7(SnMe2)2(L)

The complexes [(OC)₄Os(PbMe₂)]₂ (3) and [(OC)₄OsSnBu ₂ ]₂ (4) have been prepared from be reaction of Na₂[Os(CO)₄] with Me₂PbCl₂ and Bu ₂ SnCl₂, respectively, in THF and their X-ray crystal structures determined. The red derivative,3, was light-sensitive in solution. The reactions or [(OC)₄ Os(SnMe₂)]₂ (2), or its decarbonylated derivative [Os₃(CO)₇(SnMe₂)₂]₂ (7), with olefins or phosphorus donor ligands have also been investigated, and the structures of two derivatives, viz. [Os₂(CO)₇(SnMe₂)₂(C₂H₄)] (5a) and [Os₂(CO)₇(SnMe₂)₂(PMe₃)] (6a), have been determined; the noncarbonyl ligand occupies an equatorial site in each case. The X-ray crystal structures of all these compounds, like those of [(OC)₄Os(EMe₂)]₂ (E=Ge (1), Sn (2)) which have been reported previously, show leaning of the axial carbonyl ligands toward the metal tetracycle, i.e., an umbrella effect. Crystallographic data for compound3: space group, P2₁/a;a=13.4404(13) Å,b=10.7494(14) A,c=148967(18) A,=98.204(9)°,R=0.035, 1983 observed reflections. For compound4: space group,P1;a=9.016(1) Å,b=9.370(1),c=11.334(1) A, =103.67(1)°,=100.30(1)°, =115.03(1)°, R=0.046, 2026 observed reflections. For compound5a: space group,P1;a=9.2933(11)Å,b=9.7181(3),c=12.2508(15) A, =89.21(1)°,=87.61(1)°, =86.13(1)°,R=0.038, 2770 observed reflections. For compound6a space groupP1:a=8.7244(9)Å,b=10.9318(6),c=13.2560(13) A, =87.815(6)°,=83.655(8)°, =82.343(6)°, R=0.030, 3497 observed reflections.     

Thermal Behaviour of Metal Complexes of 6-(2-Pyridylazo)-3-acetamidophenol

The present work aims chiefly to study the thermal behaviour of complex compounds with general formula: [M(HL)xH₂O](A)yH₂O (where HL=C₁₃H₁₁N₄O₂=6-(2-pyridylazo)-3-acetamidophenol (PAAP), M=Cu(II), Zn(II), Cd(II) and Fe(III) x=1, 3; y=2, 5) while A=CH₃COO^– (Ac), Cl₂. The second formula is [M(H₂L)xH₂O]Cl₂yH₂O, (where H ₂ L=C₁₃H₁₂N₄O₂ (PAAP), M=Ni(II), Co(II) x=3; y=4, 6). The compounds were identified by elemental analysis, FT-IR spectra and TG/DTG,DTA methods. It was found that during the thermal decomposition of complex compounds water molecules of crystallization are released in the first step. In the next step the pyrolysis of organic ligand takes place. Metal oxide remained as a solid product of the thermal decomposition. Mass spectroscopy has been used for the determination of the thermal decomposition on the intermediate products. It was found that the thermal stability of the studied compounds increases as the ionic radii decreases. The activation energy E, the entropy change S ^*, the enthalpy H ^* change and Gibbs free energy change G ^* were calculated from TG curve.This revised version was published online in November 2005 with corrections to the Cover Date.     

New Molybdenum(V) Complexes Prepared by the Oxidation of Dinuclear Quadruply-Bonded Molybdenum(II) Monothiocarboxylates

Oxidation of molybdenum(II) thiopivalate and thiobenzoate in the presence of -picoline or pyridine results in the formation of dinuclear molybdenum(V) complexes of the general formulae [Mo₂O₂(-O)₂(-SO₄)L₄] with L = -picoline or pyridine and [Mo₂O₂(-O)(-S)(-SO₄)L₄] with L = -picoline. As determined by X-ray structure analysis, two complexes with -picoline differ in their bridging cores: In one complex, two Mo atoms are doubly bridged through two oxygen atoms; in the other, one Mo atom is doubly bridged through oxygen and sulfur atoms. However, they both crystallize together. The product is solvated with -picoline and water molecules. Molybdenum atoms exhibit distorted octahedral coordinations. The same complexes were prepared also through direct reactions of [Mo₂O₃(O₂CCH₃)₄] with thiopivalic and thiobenzoic acid in the presence of -picoline or pyridine. The appearance of the oxo-oxygens and sulfido-sulfur as well as sulfato ligand is explained by the molybdenum-catalyzed oxidation of thiocarboxylates.     

Verfeinerung der Kristallstruktur von Kupfer(II)-hydroxichlorid,Cu(OH)Cl

The crystal structure of Cu(OH)Cl [a=5.555 (2) Å,b=6.671 (4) Å,c=6.127 (2) Å, =114.88 (3)°, space group P2_I/a,Z=4] was refined for 810 observed reflections with sin /0.80 Å^–1 toR=0.035. Crystals were synthesized under hydrothermal conditions. The copper atom is planar four coordinated by three oxygen atoms and one chlorine atom; two further chlorine atoms complete its coordination. The copper polyhedra share edges to build up sheets, which are connected by hydrogen bonds to the chlorine atoms of adjacent sheets.

     

Synthesis and X-ray structural analysis of a unique Co-crystallization complex of [NaSal]2DB24C8 and [KSal]2DB24C8

Sodium salicylate (NaSal where Sal=2-hydroxybenzoate), when mixed with dibenzo-24-crown-8 (DB24C8) yields a bimetallic complex [NaSal]₂DB24C8 in most polar organic media, while potassium salicylate (KSal) under similar conditions shows a tendency to yield 11 or 21 complexes depending upon medium or synthesis. However, the presence of both NaSal and KSal together results in a unique mixed cation complex of composition NaKSal₂DB24C8. This product melts sharply (190-92°C) without decomposition, displays IR spectral characteristics comparable to those of [Na(Sal)]₂DB24C8, and is stable in aqueous media as shown by the detectable cation effect on the UV absorption bands of Sal and DB24C8. Single crystal X-ray analysis of NaK(Sal)₂DB24C8 reveals that the system represents a co-crystallization complex of individual (KSal)₂DB24C8 and (NaSal)₂DB24C8 molecules. The crystals are monoclinic,P2₁/c,a=19.976(2) Å,b=9.031(1) Å,c=25.541(5) Å,=122.065(9)°, ų,T=298 K,Z=2+2, CuK =1.5418 Å, and 2 (2.5°–100°). FinalR factor for the 3012 observed reflections (F>3) is 0.092. Both the Na₂- and K₂-molecules possess crystallographic centers of symmetry with one metal and its associated anion on each side of the crown ring. However, the conformations of the crowns are very different in the two molecules, with the K₂-crown being nearly planar and the Na₂-crown being quite puckered. Four oxygen atoms from the DB24C8 (KO, 2.680–2.908 Å) and three carboxyl oxygen atoms (KO, 2.472–2.708 Å) from separate salicylate ions coordinate with each potassium. Three oxygens from the crown (NaO, 2.536–2.65 Å) and three carboxyl oxygens (NaO, 2.31–2.563 Å) coordinate with each sodium. The salicylate ions lie on opposite sides and nearly perpendicular (77.2°, Na₂-molecule; 82.7° K₂-molecule) to each crown but coordinate to both of the metal ions within a molecule. The K⁺K⁺ and Na⁺Na⁺ distances in the respective molecules are 3.95 and 3.34 Å. Supplementary Data relating to this article are deposited with the British Library as Supplementary Publication No. SUP 82044 (18 pages).     

Complexing equilibria and redox potentials of the Ag(II)/Ag(I) system in the presence of 2,2′:6′,2″-terpyridine in water

Summary The conditional protonation constants (=0.1) for 2,2:6,2-terpyridine, logK ₁=4.93, logK ₂=3.69, were determined by thepH-metric method. The compositions of complexes of Ag²⁺ and Ag⁺ ions with 2,2:6,2-terpyridine (tp) were studied and equilibria of the complex formation process were described. The values of conditional complex formation constants are as follows: for Ag(tp) ₂ ⁺ :log₀₁=5.79, log₀₂=9.68, for Ag(tp) ₂ ²⁺ :log₀₂=25.31, while the conditional constant of the Ag(tp)NO₃ precipitate formation is:K _SO=2.45·10⁴. Using coulometric and chronovoltamperometric measurements, the redox systems being formed in the complex solutions of Ag(II) and Ag(I) were determined and described including their formal potentials.

---

Komplexibildungsgleichgewichte und Redoxpotentiale des Systems Ag(II)/Ag(I) in Gegenwart von 2,2:6,2-Terpyridin in Wasser

Zusammenfassung Mit Hilfe derpH-metrischen Methode wurden die konditionalen Protonationskonstanten (=0.1) von 2,2:6,2-Terpyridin bestimmt: logK ₁=4.93, logK ₂=3.69. Es wurde auch die Zusammensetzung der Komplexe von Ag(II) und Ag(I) mit 2,2:6,2-Terpyridin(tp) bestimmt sowie die Gleichgewichte der komplexbildung beschrieben. Die Werte der Konditionalkomplexbildungskonstanten sind: für Ag(tp) ₂ ⁺ :log₀₁=5.79, log₀₂=9.68, für Ag(tp) ₂ ²⁺ :log₀₂=25.31 und für das Löslichkeitsprodukt Ag(tp)NO₃:K _SO ^–1 =4.08·10^–5. Die in Komplexlösungen von Ag(II) und Ag(I) vorliegenden Redoxsysteme wurden mittels cyclischer Voltametrie und Coulometrie untersucht und die Formalpotentialwerte dieser Systeme in Wasser bestimmt.

     

Crystal structure and spectroscopic study of di-μ(1,1)-azido-di-μ(0,0-nitrato)tetrakis(3,5-lutidine)dicopper(II), [Cu(N3) (NO3) (3,5-lutidine)2]2

A mixed ligand 12 complex of copper(II) azide with 3,5-lutidine, namely di-(1,1)-azido-di(0,0)-nitrato)tetrakis(3,5-lutidine)dicopper(II) has been prepared and characterized by X-ray crystallographic and spectroscopic methods. The dimeric molecule, which possesses a crystallographic inversion center, contains two(1,1) bridging azido ligands. Each copper(II) atom in the cyclic Cu₂N₂ unit is further coordinated by two oxygen atoms from two(0,0-nitrato) bridges at Cu-O distances of 2.465(3) and 2.568(3) Å and two nitrogen atoms from the lutidine molecules [Cu-N=2.003(3) and 2.012(3) Å] to give a distorted tetragonal bipyramid. Both azido ligands are linear [N-N-N angle=179.0(4) and asymmetric N-N=1.207(4) and N-N=1.135(5) Å]. The azido bridges produce a rather short Cu Cu distance of 3.013(2) Å. Infrared and electronic data are presented and discussed.     

Copper(II) complexes of schiff bases derived of 2-hydroxy-3-naphthaldehyde. The crystal and molecular structures of bis-{(phenyl)[(2-oxo-3H-naphth-3-ylidene)methyl]aminato}copper(II) and bis-{(benzene-4-trifluoromethyl)[(2-oxo-3H-naphth-3-ylidene)-methyl]aminato}copper(II)

Summary The Schiff base ligands, 3-[(Phenyl)-2-hydroxy-3H-Naphth-3-ylidene)methyl]aldamine (1) and 3-[(benzene-4-trifluoromethyl)-2-hydroxy-3H-naphth-3-ylidene)methyl]aldamine (2), and their corresponding Cu(II) complexes (I andII were synthesized. The crystal and molecular structures ofI andII were determined. CompoundI crystallizes in the triclinic crystal systema=10.804(5),b=12.589(5), andc=10.369(3) (Å), =107.72(3), =95.75(3), and =76.32(4)(°), in the space group P withZ=2. CompoundII crystallizes in the triclinic crystal systema=10.718(2),b=13.861(4), andc=10.110(9) (Å), =95.99(2), =90.16(2), and =93.90(2)(°), in the space group P withZ=2. The geometry around the metal atom in both complexesI andII is square planar.

---

Kupfer(II)-Komplexe von Schiffbasen von 2-Hydroxy-3-naphthaldehyd. Die Kristall-und Molekülstrukturen von Bis{(phenyl)[(2-oxo-3H-naphth-3-yliden)methyl]aminato}kupfer(II) und Bis{(benzen-4-trifluoromethyl)[(2-oxo-3H-naphth-3-yliden)methyl]aminato}kupfer(II)

Zusammenfassung Es wurden die Schiffbasen-Liganden 3-[(Phenyl)-2-hydroxy-3H-naphth-3-yliden)-methyl]aldamin (1) und 3-[(Benzen-4-trifluoromethyl)-2-hydroxy-3H-naphth-3-yliden)-methyl]aldamin (2) inklusive der entsprechenden Kupfer(II)-KomplexeI undII dargestellt. VonI undII wurden die Kristallstrukturen ermittelt. KomplexI kristallisiert im triklinen System mita=10.804(5),b=12.589(5),c=10.369(3) Å, =107.72(3), =95.75(3) und =76.32(4)° in der Raumgruppe P mitZ=2. VerbindungII kristallisiert ebenfalls im triklinen System mita=10.718(2),b=13.861(4),c=10.110(9) Å, =95.99(2), =90.16(2) und =93.90(2)° in der Raumgruppe P mitZ=2. Die Geometrie rund um Cu ist in beiden Komplexen quadratisch-planar.

     

Mixed ligand complexes involving aminoacid dithiocarbamates,substituted phosphines and nickel(II)

Mixed ligand complexes involving four aminoacid dithiocarbamates (RRdtc=glydtc^– (R=H; R=H), methdtc^– (R=H; R=C₃H₇S), sardtc^– (R=Me; R=H), trydtc^– (R=H; R=C₉H₈N), substituted phosphines [PPh₃, Ph₂PCH₂CH₂PPh₂(dppe)] and nickel(II) are reported. All are diamagnetic. Thermal analyses of the complexes are in keeping with the proposed formulae. Thermal decomposition of the dithiocarbamate moiety proceeds through the formation of Ni(SCN)₂. PPh₃ and dppe are lost in the initial decomposition stages.     

Synthesis and physico-chemical studies of some polynuclear mixed carboxylate complexes of nickel(II)

A number of polynuclear mixed carboxylates of nickel(II) with the general composition [Ni(OOCCH₃)_2–n (OOCR) _n ] _x (whereR=C₁₃H₂₇, C₁₅H₃₁, C₁₇H₃₅ and C₂₁H₄₃ andn=1 or 2) have been synthesized by the transacylation reactions of anhydrous nickel acetate with higher carboxylic acids in refluxing toluene. On recrystallization from benzene-alcohol mixtures, mono-alcoholate complexes, Ni(OOCCH₃)_2–n (OOCR) _n ·ROH (whereR=CH₃ and C₂H₅) have been isolated. All these derivatives have been characterized by the molecular weight determinations, infra-red and electronic reflectance spectra and magnetic susceptibility measurements.

---

Synthese und Eigenschaften einiger gemischter Carboxylat-Komplexe von Nickel(II)

Zusammenfassung Komplexe des Typs [Ni(OOCCH₃)_2–n (OOCR) _n ] _x (mitR=C₁₃H₂₇, C₁₅H₃₁, C₁₇H₃₅ und C₂₁H₄₃,n=1 oder 2) wurden aus wasserfreiem Nickelacetat mit höheren Carbonsäuren in siedendem Toluol erhalten. Bei der Kristallisation aus Benzol-Alkohol-Mischungen wurden Monoalkoholate Ni(OOCCH₃)_2–n (OOCR) _n ·ROH (mitR=CH₃ und C₂H₅) isoliert. Die Charakterisierung der Komplexe erfolgte mittels Molekulargewichtsbestimmung, Infrarot- und Elektronenspektren und der Messung der magnetischen Susceptibilität.

     

Kinetics and mechanism of the hydrolysis of sodium carboxymethylcellulose (Na-CMC) by a cellulase complex

TheSomogyi-Nelson colorimetric method is applied in a new manner more suitable for evaluating the kinetics of the enzyme hydrolysis of sodium carboxymethylcellulose (Na-CMC) catalyzed by the cellulase complex. By means of selective inhibition of a chosen enzyme from the cellulase complex it became possible to trace the effect of the other enzymes included in its composition.

---

Kinetik und Mechanismus der Hydrolyse von Natriumcarboxymethylcellulose (Na-CMC) durch einen Cellulase-Komplex

Zusammenfassung Die kolorimetrische Methode nachSomogyi undNelson wird nach einem neuen Verfahren zur Verfolgung der Kinetik der hydrolytischen Spaltung von Natriumcarboxymethylcellulose (Na-CMC), katalysiert durch den Cellulase-Komplex, angewandt. Durch selektive Inhibierung eines bestimmten Enzyms des Cellulase-Komplexes kann man die Wirkung der anderen zu seiner gesamten Zusammensetzung gehörenden Enzyme verfolgen.

---

Symbols Used E enzyme (E—cellulase;E—exo-cellobiohydrolase;E—-glucosidase) - [E] _w weight concentration of enzymeE - S substrate (Na-CMC—sodium carboxymethylcellulose) - [S]₀ weight concentration of substrateS - I inhibitor (I—lactose;I—calcium chloride;I—condurrite-B-epoxide) - P product (P—oligosaccharides;P—cellobiose;P—D-glucose) - P end product (K , K , K ) - DP degree of polymerization - DS degree of substitution - ES enzyme-substrate complex (E S, E S, E S) - EP enzyme-product complex (E P, E P) - EI enzyme-inhibitor complex (E I, E I, E I) - M _s molecular mass of substrateS - K _s substrate constant (K _s , K _s , K _s ) - K _I inhibitor constant (K _I , K _I , K _I ) - K _m Michaelis-Menten constant - k ₊₁,k ₊₂ (k ₊₂ ,k ₊₂ ,k ₊₂ ) forward rate constants - k _–1 reverse rate constant - ₀ initial rate of reaction - V maximal reaction rate - A change in absorbance - molar absorption coefficient - wavelength Herrn Prof. Dr.Hans Tuppy zum 60. Geburtstag herzlichst gewidmet.     

The oxidative addition of hydrogen sulfide to the electron-rich triple bond: The isolation and characterization of compounds that contain the Re2(μ-H)(μ-SH) cluster unit

The reactions of Re₂X₄(-dppm)₂ (X=Cl or Br; dppm=Ph₂PCH₂PPh₂) with H₂S in THF afford the dirhenium (III) complexes Re₂(-H)(-SH)X₄(-dppm)₂, the first examples of the oxidative addition of an S-H unit across an electron-rich metal-metal triple bond. The bromide complex Re₂(-H)(-SH)Br₄(-dppm)₂ (C₂H₅)₂O crystallizes in the space group P2₁/n witha=16.631(2) Å,b=15.967(3) Å,c=19.904(2) Å, =92.698(7)°,V=5279(2) ų, andZ=4. The structure which was refined toR=0.053 (R _w=0.070) for 4903 data withI>3.0(I), shows the presence of an edge-shared bioctahedral geometry with a very short Re-Re distance of 2.4566(7) Å. While the hydrogen atoms of the -H and -SH ligands were not located in the X-ray structure determination, their presence is confirmed by IR and¹H NMR spectroscopy.