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Showing papers by "Bernt Krebs published in 1996"


Journal ArticleDOI
TL;DR: A remarkable diversity is also seen in the structures of the active sites of these di- and trinuclear metalloenzymes, even for enzymes that catalyze very similar reactions, including hydrolytic cleavage of phosphomono-, -di- and -triester bonds, phosphoanhydride bonds as well as of peptide bonds or urea.
Abstract: Numerous studies, both in enzymatic and nonenzymatic catalysis, have been undertaken to understand the way by which metal ions, especially zinc ions, promote the hydrolysis of phosphate ester and amide bonds. Hydrolases containing one metal ion in the active site, termed mononuclear metallohydrolases, such as carboxypeptidase. A and thermolysin were among the first enzymes to have their structures unraveled by X-ray crystallography. In recent years an increasing number of metalloenzymes have been identified that use two or more adjacent metal ions in the catalysis of phosphoryl-transfer reactions (R-OPO3 + R′-OH R′-OPO3 + R-OH; in the case of the phosphatase reaction R′-OH is a water molecule) and carbonyl-transfer reactions, for example, in peptidases or other amidases. These dinuclear metalloenzymes catalyze a great variety of these reactions, including hydrolytic cleavage of phosphomono-, -di- and -triester bonds, phosphoanhydride bonds as well as of peptide bonds or urea. In addition, the formation of the phosphodiester bond of RNA and DNA by polymerases is catalyzed by a two-metal ion mechanism. A remarkable diversity is also seen in the structures of the active sites of these di- and trinuclear metalloenzymes, even for enzymes that catalyze very similar reactions. The determination of the structure of a substrate, product, stable intermediate, or a reaction coordinate analogue compound bound to an active or inactivated enzyme is a powerful approach to investigate mechanistic details of enzyme action. Such studies have been applied to several of the metalloenzymes reviewed in this article; together with many other biochemical studies they provide a growing body of information on how the two (or more) metal ions cooperate to achieve efficient catalysis.

553 citations


Journal ArticleDOI
TL;DR: All three structures reported herein support a mechanism of phosphate ester hydrolysis involving interaction of the substrate with Zn(II) followed by a nucleophilic attack on the phosphorus by an Fe(III)-coordinated hydroxide ion.

353 citations


Journal ArticleDOI
TL;DR: Two novel tridentate dinucleating ligands containing benzimidazole were prepared and the interpretation of these data, including multiple scattering calculations, together with UV-vis titrations, shows that the complexes have the same structure in the crystalline state as well as in methanolic solution.
Abstract: Two novel tridentate dinucleating ligands containing benzimidazole were prepared, 1,3-bis(2-benzimidazolyl)-2-propanol (Hbbp, 1) and 1,5-bis(2-benzimidazolyl)-3-pentanol (Hbbpen, 2). Their complexing properties toward copper were studied in order to obtain structural and functional models for catechol oxidases. Syntheses and crystal structures of dinuclear Cu(II) complexes derived from these ligands are reported. [Cu2bbp2](ClO4)2·2MeOH, 3, crystallizes in the triclinic space group P1 with the following unit cell parameters: a = 7.702(3) A, b = 10.973(6) A, c = 12.396(6) A, α = 100.59(4)°, β = 99.02(4)°, γ = 98.90(4)°, V = 998.7(8) A3, and Z = 1. [Cu2bbpen2](ClO4)2·3MeOH, 4, crystallizes in the orthorhombic space group Pccn, with the following unit cell parameters: a = 17.478(9) A, b = 18.795(8) A, c = 13.888(6) A, V = 4562.2(4) A3, and Z = 4. Magnetic susceptibility measurements in the temperature ranges 4.6−459 K (3) and 4.6−425 K (4) indicate an antiferromagnetic coupling between the Cu(II) centers o...

181 citations


Journal ArticleDOI
TL;DR: Compounds 2 and 3 have one of the nickel ions in a five-coordinated, trigonal bipyramidal coordination environment and thus show a high structural similarity to the dinuclear active site of urease from Klebsiella aerogenes and their magnetic and spectroscopic properties were determined and related to those of the ure enzyme enzymes.
Abstract: Dinuclear nickel(II) complexes of the ligands 2,6-bis[bis((2-benzimidazolylmethyl)amino)methyl]-p-cresol (bbapOH), N,N,N',N'-tetrakis(2-benzimidazolylmethyl)-2-hydroxy-1,3-diaminopropane (tbpOH), N-methyl-N,N',N'-tris(2-benzimidazolylmethyl)-2-hydroxy-1,3-diaminopropane (m-tbpOH) and 1-[N,N-bis(2-benzimidazolylmethyl)amino]-3-[2-(3,5-dimethyl-1H-pyrazol-1-yl)ethoxy]-2-hydroxypropane (bpepOH) were prepared in order to model the active site of urease. The novel asymmetric structures of the dinuclear complexes were characterized by X-ray structure analysis. The complex [Ni(2)(bbapO)(ClO(4))(H(2)O)(MeOH)](ClO(4))(2).Et(2)O, 1, crystallizes in the monoclinic space group P2(1)/c, with a = 10.258(2) A, b = 19.876(3) A, c = 25.592(4) A, and beta = 97.12(2) degrees. The nickel ions in 1 are bridged by the phenoxy donor of the ligand and a perchlorate anion. The complexes [Ni(2)(tbpO)(MeCOO)(H(2)O)](ClO(4))(2).H(2)O.Et(2)O, 2, [Ni(2)(m-tbpO)(PhCOO)(EtOH)(2)](ClO(4))(2).EtOH, 3, and [Ni(2)(bpepO)(MeCOO)(H(2)O)(2)](ClO(4))(2).H(2)O.Et(2)O.2EtOH, 4, also crystallize in the monoclinic crystal system with the following unit cell parameters: 2, C2/c, a = 35.360(13) A, b = 10.958(3) A, c = 24.821(10) A, beta = 103.55(3) degrees; 3, Cc, a = 14.663(5) A, b = 32.630(13) A, c = 9.839(3) A, beta = 92.49(2) degrees; 4, C2/c, a = 27.689(13) A, b = 12.187(5) A, c = 31.513(14) A, beta = 115.01(3) degrees. The dinuclear centers of all these complexes are bridged by the alkoxy donor of the ligand and a carboxylate function. Compounds 2 and 3 have one of the nickel ions in a five-coordinated, trigonal bipyramidal coordination environment and thus show a high structural similarity to the dinuclear active site of urease from Klebsiella aerogenes. Furthermore, their magnetic and spectroscopic properties were determined and related to those of the urease enzymes. Activity toward hydrolysis of test substrates (4-nitrophenyl)urea, 4-nitroacetanilide, 4-nitrophenyl phosphate or bis(4-nitrophenyl) phosphate by the dinuclear complexes were examined by UV spectroscopic measurements.

117 citations


Journal ArticleDOI
TL;DR: In this paper, a number of enzymatalyse of metallionen have been charakterisiert, in denen zwei oder mehrere benachbarte Metallionen die Katalyse von Phosphoryl- (ROPO3 + R′OH R′OPO 3 + ROH; im Fall der Phosphatasereaktion ist R′-OH ein Wassermolekul) and von Carbonyltransferreaktionen unterstutzen, z. B
Abstract: Sowohl bei enzymatischen als auch bei nichtenzymatischen Katalysen sind zahlreiche Untersuchungen durchgefuhrt worden, um zu verstehen, wie Metallionen – besonders Zinkionen – die Hydrolyse von Phosphorsaureester- und Amidbindungen unterstutzen. Hydrolasen mit einem Metallion im aktiven Zentrum, sogenannte mononucleare Metallohydrolasen, z. B. die Carboxypeptidase A oder Thermolysin, zahlen zu den ersten Enzymen, deren Strukturen rontgenographisch aufgeklart werden konnten. In den letzten Jahren wurden zunehmend mehr Metalloenzyme charakterisiert, in denen zwei oder mehrere benachbarte Metallionen die Katalyse von Phosphoryl- (ROPO3 + R′OH R′OPO3 + ROH; im Fall der Phosphatasereaktion ist R′-OH ein Wassermolekul) und von Carbonyltransferreaktionen unterstutzen, z. B. in Peptidasen und anderen Amidasen. Diese dinuclearen Metalloenzyme katalysieren enorm viele Reaktionen dieser Art: die hydrolytische Spaltung von Phosphorsauremono-, di- und triesterbindungen, von Phosphorsaureanhydridbindungen sowie die Spaltung von Peptidbindungen oder Harnstoff. Auch die Bildung der Phosphodiesterbindung in RNA und DNA wird von Polymerasen uber einen Zwei-Metallionen-Mechanismus katalysiert. Erstaunlich vielfaltig sind auch die Strukturen der aktiven Zentren dieser di- oder trinuclearen Metalloenzyme, selbst fur Enzyme, die sehr ahnliche Reaktionen katalysieren. Die Strukturbestimmung des aktiven und inaktivierten Enzyms mit gebundenem Substrat oder Produkt, einem stabilen Intermediat oder einem Analogon einer sich im Verlauf der Reaktion bildenden Zwischenstufe ist eine leistungsstarke Methode zur Aufklarung der mechanistischen Details der Enzymkatalyse. Strukturbestimmungen sind fur viele der in diesem Artikel beschriebenen Metalloenzyme durchgefuhrt worden und liefern zusammen mit anderen biochemischen Untersuchungen einen immer besseren Einblick in die Fragestellung, wie die zwei (oder mehr) Metallionen zusammenwirken, um die Reaktionen effizient zu katalysieren.

86 citations


Journal ArticleDOI
TL;DR: In this article, the X-ray structure of the antitumor active Pt compound [Pt(bmic)Cl2] (bmic = bis-(N-methylimidazol-2-yl)carbinol) and its interaction with short DNA fragments has been investigated using NMR spectroscopy.
Abstract: To obtain insight into the structure−activity relationships of new antitumor active platinum compounds the X-ray structure of the antitumor active Pt compound [Pt(bmic)Cl2] (bmic = bis-(N-methylimidazol-2-yl)carbinol) (1) and its interaction with short DNA fragments has been investigated using NMR spectroscopy. For comparison also the structurally related compound [Pt(bmi)Cl2] (bmi = N1,N1‘-dimethyl-2,2‘-biimidazole) (2), which is not antitumor active, has been studied. The structure of the compound [Pt(bmic)Cl2] (1) was characterized by single-crystal X-ray structure determination. Compound 1 crystallizes in the monoclinic space group P21/n, with a = 10.055(3) A, b = 11.802(3) A, c = 10.620(3) A, β = 103.78(2)°, V = 1224.0(6) A3 and Z = 4. Convergence was reached at wR2 = 0.1148 (all data) and R1 = 0.0476 (I > 2 (I)) for 2433 independent reflections and 156 adjustable parameters. The platinum atom is coordinated by two nitrogen and two chlorine atoms, resulting in a square planar PtN2Cl2 coordination sph...

77 citations


Journal ArticleDOI
TL;DR: In this paper, the trinuclear zinc complex [Zn3(O2CPh)2(hsalpn)2]·2MeOH 1 and the hexanuclear zinc compound[Zn6(OH)6(bmmp)3][ClO4]32]32 were characterized by single-crystal X-ray diffraction analyses.
Abstract: Reaction of Zn(ClO4)2·6H2O with pentadentate 1,3-bis(salicylidenamino)propan-2-ol (H2hsalpn) and the tridentate 4-methyl-2,6-bis(morpholinomethyl)phenol (Hbmmp) yielded the trinuclear zinc complex [Zn3(O2CPh)2(hsalpn)2]·2MeOH 1 and the hexanuclear zinc compound [Zn6(OH)6(bmmp)3][ClO4]32. The complexes were characterized by single-crystal X-ray diffraction analyses. Both structures were solved using direct methods and refined on F by full-matrix least squares. Complex 1 consists of one central zinc ion which is octahedrally co-ordinated and two terminal metals surrounded by five donor atoms in the form of a square pyramid. The left and right wing zinc ions are connected to the central metal atom via two phenolate oxygens of the dinucleating ligand and the oxygens of the benzoate ion. The six equivalent tetrahedrally co-ordinated zinc ions in 2 are arranged in form of a regular trigonal prism. Three dinuclear subunits are connected to each other by hydroxide groups. Both compounds display a new type of structure for homotri- and homohexanuclear zinc complexes.

77 citations


Journal ArticleDOI
TL;DR: In this article, the authors improved the methods of preparation for Bi8(AlCl4)2 and Bi6Cl7 and the single crystal structures for these cluster compounds were re-investigated and reinterpreted.
Abstract: The methods of preparation for Bi8(AlCl4)2 and Bi6Cl7 have been improved and the single crystal structures for these cluster compounds re-investigated and re-interpreted. In addition, conductivity measurements and band structure calculations using the tight-binding approximation have been performed on Bi6Cl7 and related subvalent bismuth halides. – Bi8(AlCl4)2 consists of isolated AlCl4- anions and rather undistored square-antiprismatic Bi82+ clusters with an average Bi–Bi distance of 3.10 A. Relatively short intercluster Bi–Bi contacts of 3.90 A suggest weak bonding interactions between the Bi82+ units. In contrast, the structure determination of Bi6Cl7 implies that this structure should be regarded as being composed of discrete Bi95+ clusters and a polymeric BiIII–Cl anionic lattice including infinite, distorted α1[Bi2Cl24+] chains. According to the experimental and theoretical results, the Bi6X7 (X = Cl, Br) family of subvalent bismuth halide compounds are anisotropic semiconductors along the crystallographic c axis. The conductivity is mediated by the onedimensional α1[Bi2Cl24+] chains. These are interconnected with the Bi95+ clusters, which are acting as electron reservoirs. The related BiX (X = Br, I) family of subvalent bismuth halides are shown to be anisotropic semiconductors in the crystallographic b direction.

72 citations


Journal ArticleDOI
TL;DR: The asymmetric complex was prepared in order to mimic the substrate uptake in the dinuclear active site of ureases and the magnetic and spectroscopic properties of the complex were determined and related to those of the urease enzymes.
Abstract: The synthesis of the novel asymmetric ligand 1-[bis(2-pyridylmethyl)amino]-3-[2-(2-pyridyl)ethoxy]-2-hydroxypropane (ppepOH) is reported. The ligand is suitable to form asymmetric dinuclear complexes with various transition metal ions. As an example, the synthesis and X-ray structure analysis of the dinickel(II) complex [Ni(2)(ppepO)(C(6)H(5)COO)(2)(CH(3)COOH)]ClO(4).C(4)H(10)O are described. The complex crystallizes in the monoclinic space group P2(1)/n with the following unit cell parameters: a = 13.704(10) A, b = 14.849(10) A, c = 22.697(14) A, beta = 96.80(5) degrees, Z = 4. The nickel(II) ions are bridged by the alkoxy donor of the ligand and two benzoate anions. The hexadentate ligand leaves a free coordination site at one of the nickel(II) ions, which is occupied by a monodentate coordinated acetic acid molecule. The coordination of the neutral acetic acid molecule is selectively stabilized by a strong intramolecular hydrogen bond of the acidic proton to the m-alkoxo bridge of the dinuclear complex. The asymmetric complex was prepared in order to mimic the substrate uptake in the dinuclear active site of ureases. The magnetic and spectroscopic properties of the complex were determined and related to those of the urease enzymes.

47 citations


Journal ArticleDOI
TL;DR: Li4−2xSr2+xB10S19 (x ≈ 0.27) and Na6b10S18 were derived from the reaction of strontium sulfide and lithium sulfide (sodium sulfide) with boron and sulfur at 700°C in graphitized silica tubes as mentioned in this paper.
Abstract: Li4−2xSr2+xB10S19 (x ≈ 0,27) und Na6B10S18 wurden aus der Summenformel entsprechenden Mengen Strontiumsulfid und Lithiumsulfid (Natriumsulfid), amorphem Bor und Schwefel bei 700°C in graphitierten Quarzglasampullen dargestellt. Li4−2xSr2+xB10S19 (x ≈ 0,27) kristallisiert monoklin in der Raumgruppe P21/c mit a = 10,919(2) A, b = 13,590(3) A, c = 16,423(4) A, und β = 90,48(2)°, Na6B10S18 tetragonal in der Raumgruppe I41/acd mit a = 14,415(3) A, c = 26,137(4) A. Beide Strukturen enthalten supertetraedrische B10S20-Einheiten, die uber Tetraederecken zu einem dreidimensionalen polymeren anionischen Raumnetzwerk im Falle des Na6B10S18 bzw. zu eindimensionalen Anionen-Ketten im Falle des Li4−2xSr2+xB10S19 (x ≈ 0,27) verbunden sind. Alle Boratome haben tetraedrische BS4-Koordination (die BS-Abstande variieren von 1,879(5) A bis 1,951(5) A (1,875(10) A bis 1,987(9) A)). Die Strontium- und Lithium-(Natrium-)Kationen befinden sich in ausgedehnten Kanalen innerhalb des Anionengerusts. Synthesis and Crystal Structures of Li4−2xSr2+xB10S19 (x ≈ 0.27) and Na6B10S18. Two Novel Thioborates with Highly Polymeric Macro-tetrahedral Networks Li4−2xSr2+xB10S19 (x ≈ 0.27) and Na6B10S18 were prepared from the reaction of strontium sulfide and lithium sulfide (sodium sulfide) with boron and sulfur at 700°C in graphitized silica tubes. Li4−2xSr2+xB10S19 (x ≈ 0.27) crystallizes in the monoclinic space group P21/c with a = 10.919(2) A, b = 13.590(3) A, c = 16.423(4) A, and β = 90.48(2)°, Na6B10S18 in the tetragonal space group I41/acd with a = 14.415(3) A, c = 26.137(4) A. Both structures contain supertetrahedral B10S20 units which are linked through tetrahedral corners to form a three-dimensional polymeric network in the case of Na6B10S18 and one-dimensional chains in the case of Li4−2xSr2+xB10S19 (x ≈ 0.27). All boron atoms are in tetrahedral BS4 coordination (BS bond lengths vary from 1.879(5) to 1.951(5) A (1.875(10) to 1.987(9) A)). The strontium and lithium (sodium) cations are located within large channels formed by the anions.

34 citations



Patent
21 Aug 1996
TL;DR: BleBleach composition comprising one or more bleaching agents and polyoxometallates of the formula: (Q)q(A a X x M m O y Z z(H2O)b).cndot.
Abstract: Bleach composition comprising one or more bleaching agents and one or more polyoxometallates of the formula: (Q)q(A a X x M m O y Z z(H2O)b).cndot.cH2O as bleaching catalyst, the symbols Q, A, X, M, Z, q, a, x, m, y, z, b and c being as defined in the description. These polyoxometallates increase the bleaching activity, especially at lower washing temperatures.

Journal ArticleDOI
TL;DR: In this paper, temperature dependent magnetic susceptibility measurements of the reduced and of the oxidized diiron forms of purple acid phosphatase from kidney bean (KBP) and from bovine spleen (BSP) have been carried out in the temperature range 4.2-220 K in order to detect the strength of the exchange coupling between the two metal centers in the active site.

Journal ArticleDOI
TL;DR: Li3BS3 and LiSrBS3: New Orthothioborates with Trigonal Planar Boron Coordination as discussed by the authors, which represent new A3BX3 resp. AA′bX3-Strukturtypen.
Abstract: Es wird uber die beiden Orthothioborate Li3BS3 (Pnma; a = 8,144(1) A, b = 10,063(2) A, 6,161(1) A; Z = 4) und LiSrBS3 (Pnma; a = 7,557(1) A, b = 9,083(2) A, c = 7,049(1) A; Z = 4) berichtet. Die beiden neuen Phasen wurden durch Hochtemperatur-Schmelzreaktion aus den Metallsulfiden, amorphem Bor und Schwefel bei 700°C dargestellt. Beide Verbindungen enthalten isolierte, planare [BS3]3−-Anionen. Die Lithiumionen sind vierfach (Li3BS3) bzw. sechsfach (LiSrBS3) von Schwefel umgeben, das Strontiumion weist eine achtfache Schwefelkoordination auf. Li3BS3 und LiSrBS3 bilden neue A3BX3 bzw. AA′BX3-Strukturtypen. Li3BS3 and LiSrBS3: New Orthothioborates with Trigonal Planar Boron Coordination We report on the two new orthothioborates Li3BS3 (Pnma; a = 8.144(1) A, b = 10.063(2) A, 6.161(1) A; Z = 4) and LiSrBS3 (Pnma; a = 7.557(1) A, b = 9.083(2) A, c = 7.049(1) A: Z = 4). The two new phases were prepared by reaction of the metal sulfides, amorphous boron, and sulfur at 700°C. Both compounds contain isolated, planar [BS3]3−-anions. The lithium ions have fourfold (Li3BS3) and sixfold (LiSrBS3) sulfur coordination, the strontium ion shows an eightfold sulfur coordination. The two compounds represent new A3BX3 resp. AA′BX3 structure types.

Journal ArticleDOI
TL;DR: In this article, the crystal structure of Ag5−xTe3 was determined by single crystal X-ray structure analysis, and the homogenity region was derived from the structure.
Abstract: Die Kristallstruktur von Ag5−x Te3 wurde durch Einkristall-Rontgenstrukturanalyse ermittelt. Die Struktur besitzt hexagonale Symmetrie (P62m, Nr. 189) mit a = 13,456(9) A und c = 16,917(9) A. Die Verbindung besteht aus beweglichen Silberkationen, die in einem Tellur-Gerust von Frank-Kasper-Polyedern verteilt sind. Tellur liegt als Te2− und als Te22−-Hantel vor und bildet drei verschiedene Arten von Tetraederlucken. Die Verteilung des Silbers auf die Tetraederlucken wird beschrieben. Daraus resultieren Vorschlage fur mogliche Diffusionspfade. Schlieslich wird der Homogenitatsbereich von Ag5−xTe3 aus der Struktur hergeleitet. The Crystal Structure of Synthetic Stuetzite, Ag5−xTe3 The crystal structure of Ag5−xTe3 was determined by single crystal X-ray structure analysis. The structure is of hexagonal symmetry (P 62m, Nr. 189) with a = 13.456(9) A and c = 16.917(9) A. The compound consists of highly mobile silver cations distributed in a tellurium framework forming Frank-Kasper polyhedra. Tellurium exists as Te2− as well as Te22−-dumbbells and forms three types of tetrahedral sites. A description of the distribution of silver on the tetrahedral voids is given resulting in a suggestion of possible diffusion paths. Finally the homogenity region of Ag5−xTe3 is derived from the structure.

Journal ArticleDOI
TL;DR: The Tripodligand N-tris (2-benzimidazolylmethyl)-amine (ntb) was used for the preparation of zinc(II) and iron(III) complexes as mentioned in this paper.
Abstract: The tripodal ligand N-tris(2-benzimidazolylmethyl)-amine (ntb) was used for the preparation of zinc(II) and iron(III) complexes, [Zn(SCN)(ntb)](SCN) · iPrpOH (1) and [Fe(acac)(ntb)](ClO4)2 · 2CH2Cl2 · iPrpOH (2). 1 has a highly distorted trigonal-bipyramidal ZnN5 coordination geometry. The donor atoms are nitrogens of one amine, three benzimidazoles and one SCN−. A striking feature of the complex is the length of the ZnNamine bond of 2.539(6)A. The octahedral N4O2 coordination sphere of the iron in 2 is less distorted than that of the zinc in 1. The metal is surrounded by an amine and three benzimidazole nitrogens of the ligand and two oxygens of the bidentate acetylacetonate co-ligand. The FeO bond lengths differ by about 0.1 A. As for the unusual long ZnN bond in 1 this is a result of a trans effect. 1 crystallizes in the space group P1 with: a = 9.530(1)A, b = 13.402(1)A, c = 13.578(2)A, α = 98.83(1), β = 95.19(1), γ = 101.21(1)°, Z = 2; 2 is also triclinic, space group P1, with: a = 9.875(6)A, b = 12.929(10)A, c = 18.635(15)A, α = 94.95(8)°, β = 101.01(6)°, γ = 111.09(4)°, Z = 2. Tripodliganden: Darstellung verzerrter Koordinationspolyeder in biomimetischen Metallkomplexen. Kristallstrukturen von [Zn(SCN)(ntb)](SCN) · iPrpOH und [Fe(acac)(ntb)](ClO4)2 · 2 CH2Cl2 · iPrpOH, ntb = N-Tris(2-benzimidazolylmethyl)amin Der Tripodligand N-Tris(2-benzimidazolylmethyl)amin (ntb) wurde zur Synthese eines Zink(II)- und eines Eisen(III)-Komplexes, [Zn(SCN)(ntb)](SCN) · iPrpOH (1) und [Fe(acac)(ntb)](ClO4)2 · 2 CH2Cl2 · iPrpOH (2), eingesetzt. Der Zinkkomplex hat eine stark verzerrte trigonal-bipyramidale Koordinationssphare. Die koordinierenden Atome sind ein Amin-N, drei Benzimidazol-N und ein SCN−-N-Atom. Auffallig hier ist der 2.539(6)A grose ZnNamin-Bindungsabstand. Das Koordinationspolyeder des Eisenkomplexes ist weniger stark verzerrt als das in 1 und wird von einem Amin- und drei Benzimidazol-Stickstoffatomen des Liganden sowie zwei Sauerstoffatomen des Acetylacetonats gebildet. Die FeO-Bindungslangen zeigen eine Differenz von ca. 0.1 A, die wie die ungewohnlich lange ZnN-Bindung durch einen Trans-Effekt verursacht wird. 1 kristallisiert triklin in der Raumgruppe P1 mit: a = 9.530(1), b = 13.402(1), c = 13.578(2)A, α = 98.83(1), β = 95.19(1), γ = 101.21(1)°, Z = 2; 2 ist ebenfalls triklin, P1, mit: a = 9.875(6), b = 12.929(10), c = 18.635(15)A, α = 94.95(8), β = 101.01(6), γ = 111.09(4)°, Z = 2.

Journal ArticleDOI
TL;DR: In this article, a quadratisch-pyramidales [TeBr5]− -Anion isoliert werden, where the coordination sphere of the anion is completed to a distorted octahedron by weak interaction with a dioxane molecule.
Abstract: Tiefrote Kristalle der Zusammensetzung [H3O][TeBr5] · 3 C4H8O2 (1) wurden aus einer gesattigten Losung von TeBr4 in wasserhaltigem 1,4-Dioxan dargestellt. In der Verbindung (Raumgruppe P21/m, a = 8.922(4) A, b = 13.204(7) A, c = 9.853(5) A, β = 91.82(4)° bei 150 K) konnte erstmals ein quadratisch-pyramidales [TeBr5]− -Anion isoliert werden. Dessen Koordinationspolyeder wird durch eine schwache Wechselwirkung mit einem 1,4-Dioxan-Molekul zu einem verzerrten Oktaeder vervollstandigt. Die [H3O]+-Kationen sind durch 1,4-Dioxan-Molekule zu Ketten verknupft. Die Saure ist bei Raumtemperatur nur in ihrer Mutterlauge stabil. [H3O]2[SeBr6] (2) (Raumgruppe Fm3m, a = 10.421(1) A bei 170 K) ist eine hochsymmetrisch kristallisierende Bromoselen(IV)-saure, mit der es gelang, ein nur sehr schwach durch Br-Atome des Anions koordiniertes [H3O]+-Ion zu isolieren. Die anionische Einheit besteht aus freien, unverzerrt oktaedrischen [SeBr6]2−-Ionen. Die Kristallstruktur ist isotyp zu K2[PtCl6]. Die Verbindung zeigt eine fur Halogenochalkogen(IV)-sauren bemerkenswerte thermische Stabilitat. Beide Oxoniumsalze wurden durch vollstandige Rontgenstrukturanalysen charakterisiert. Uber schwingungsspektroskopische Untersuchungen an 2 wird berichtet. New Oxonium Bromochalcogenates(IV) — Synthesis, Structure, and Properties of [H3O][TeBr5] · 3 C4H8O2 and [H3O]2[SeBr6] Dark red crystals of the composition [H3O][TeBr5] · 3 C4H8O2 (1) were isolated from a saturated solution of TeBr4 in 1,4-dioxane containing a small amount of water. In this compound (space group P21/m, a = 8.922(4) A, b = 13.204(7) A, c = 9.853(5) A, β = 91.82(4)° at 150 K) a square pyramidal [TeBr5]− anion has been isolated for the first time. The coordination sphere of the anion is completed to a distorted octahedron by weak interaction with a dioxane molecule of the cationic system. The [H3O]+ cations are connected to chains by dioxane molecules. At room temperature the compound is stable only in its mother liquor. Crystalline [H3O]2[SeBr6] (2) (space group Fm3m, a = 10.421(1) A at 170 K) is a bromoselenous acid of high symmetry. The [H3O]+ ion is only weakly coordinated by Br atoms of the anion. The anions are isolated octahedral [SeBr6]2− units. The structure is isotypic to the K2[PtCl6] structure. Despite being a halogenochalcogen(IV) acid, 2 exhibits a remarkable thermal stability. Both oxonium compounds were characterized by single-crystal X-ray structure analyses. Vibrational spectra of 2 are reported.

Journal ArticleDOI
TL;DR: In this paper, the 1,2,3-triphosphetenes RCPPCF3PCFF3 (3a-d) are formed as main products in reactions of phosphaalkynes RCP [R = iPr2N (1a), tBu (1b), Me2EtC (1c), 1-methylcyclohexyl (1d), and the cyclotetraphosphane PCF3)4 (2).
Abstract: Hitherto unknown 1,2,3-triphosphetenes RCPPCF3PCF3 (3a–d) are formed as main products in reactions of phosphaalkynes RCP [R = iPr2N (1a), tBu (1b), Me2EtC (1c), 1-methylcyclohexyl (1d)] with the cyclotetraphosphane (PCF3)4 (2). According to NMR results the CF3 groups in 3a–d have a trans disposition; an X-ray diffraction study of 3a confirms this structure. The PP bond lengths in 3a are equal [2.201 (2) and 2.204 (2) A] and correspond to single bonds. A considerable shortening is observed for the sp2-C–N bond (1.336 A) which, together with the elongation of the PC bond (1.746 A), indicates effective π donation of the lone pair on nitrogen. Surprisingly, 3a can be prepared in quantitative yields by reaction of the PP ylide Me3PPCF3 (6) with 1 a (molar ratio: 2:1). In contrast, the corresponding reactions of 6 with the alkyl-substituted phosphaalkynes 1b–d lead to the novel phosphorus ylides Me3PC(R)PPCF3PCF3PCF3 [R = tBu (10a), Me2EtC (10b), 1-methylcyclohexyl (10c)] in good yields. In their molecular groundstate structures, determined by X-ray diffraction, the lone pair on the phosphano P atom prefers the syn position with respect to the ylidic PC bond. An unusual lengthening of the sp2-C–C bond [1.553 (4) (10a), 1.543 (6) (10b), 1.551 (4) A (10c)] to values typical for sp3-C/sp3-C distances is observed.

Patent
14 Aug 1996
TL;DR: A bleach compsn contains: (a) a bleaching agent; and (b) a polyoxymetallate as bleach catalyst as discussed by the authors, which is used as a bleach catalyst.
Abstract: A bleach compsn contains: (a) a bleaching agent; and (b) a polyoxymetallate as bleach catalyst

Journal ArticleDOI
TL;DR: The reactions of [M(mipk)(H2O)2]2+M = Pd or Pt; mipk = 1-methylimidazol-2-yl pyridin-2 -yl ketone] with the nucleobases 1-methylthymine (Hmthy) and 1 -methyluracil(Hmura) were studied and the products characterized by X-ray structure analyses as well as by 1H NMR spectroscopy as discussed by the authors.
Abstract: The reactions of [M(mipk)(H2O)2]2+(M = Pd or Pt; mipk = 1-methylimidazol-2-yl pyridin-2-yl ketone) with the nucleobases 1-methylthymine (Hmthy) and 1-methyluracil (Hmura) were studied and the products characterized by X-ray structure analyses as well as by 1H NMR spectroscopy. Dinuclear complexes are formed with the pyrimidine-based model nucleobases, which act as secondary bridging ligands via their N3 and O4 donor functions. In all three compounds [Pd2(mipk)2(mura)2][ClO4]21, [Pd2(mipk)2(mthy)2][ClO4]22 and the isotypic compound [Pt2(mipk)2(mthy)2][ClO4]23 the nucleobases show head-to-tail arrangement. The intramolecular M ⋯ M distances vary from 2.861(1)A in 2 to 2.879(1)A in 1. By ligand-exchange reaction in aqueous media the side product [Pt(mipk)2][ClO4]2 is formed. Proton NMR studies showed that the dinuclear complexes are not stable in aqueous solution. Oxidation of 3 and [Pt2(mipk)2(mura)2][ClO4]24 to platinum blues with higher-valent Pt was not observed. Presumably this is due to the competing oxidation of the low-potential mipk ligand.


Journal ArticleDOI
TL;DR: In this paper, Kupfer et al. show that the PC-Abstande des Vierrings sind mit 1,817(2) bzw. 1.818(2,1.5) and 1.5(2.2) A erwartungsgemas erheblich langer als die PC-Bindung des η2-koordinierten Phosphaalkins 2 [1,671(2] A].
Abstract: 2-(Diisopropylamino)-phosphaethin iPr2N-CP (2) reagiert mit den Ni(0)-Komplexen [Ni(1,5-Cyclooctadien)2] bzw. [Ni(CO)3(1-Azabicyclo[2.2.2]octan)] zu dem neuen Komplex [{η4-(iPr2NCP)2}Ni{η2-(iPr2NCP)}] (5), der zwei Molekule 2 in Form des 1,3-Diphosphacyclobutadiensystems und ein Molekul 2 „side-on” koordiniert als π-Liganden enthalt. Die Molekulstruktur von 5, ermittelt durch Rontgenbeugung an Einkristallen, bestatigt die aus den NMR-Daten (1H-, 13C-, 31P) abgeleiteten Spinsysteme und Rotationsbarrieren. Die PC-Abstande des Vierrings sind mit 1,817(2) bzw. 1,818(2) A erwartungsgemas erheblich langer als die PC-Bindung des η2-koordinierten Phosphaalkins 2 [1,671(2) A]. Bei den Umsetzungen von 2 mit [(Ph3P)2Pt(C2H4)] bzw. [Co2(CO)8] entspricht das koordinative Verhalten dem von Alkinen; sie liefern die Komplexe [(Ph3P)2Pt{η2-(iPr2NCP)}] (7) mit side-on gebundenem 2 bzw. [Co2(CO)6{η2-η2-(iPr2NCP)}] mit 2 als 4e-Donorbrucke in quantitativer Ausbeute. Bei dem Versuch, aus 2 und CuCl bzw. CuI Kupfer(I)-Komplexe des Aminophosphaalkins darzustellen, bildet sich unter Einwirkung von Luft und Feuchtigkeit als einziges isolierbares Produkt das 1λ3, 3λ5-Diphospheten (iPr2N) (10) in betrachtlicher Menge (Reinausbeute: ca. 20%). Fur 10 ergibt sich aus der Kristallstrukturanalyse eine enge Beziehung zu dem Diamino-2-phosphaallyl-Kation [Me(iPr2N)]+ (12), dem 1,3-Diphosphacyclobutadien-Liganden (iPr2NCP)2 im Zweikernkomplex [{η1-μ2-(iPr2NCP)2}Ni2(CO)6] (3a) sowie zu den von Becker et al. [11 b, 35] dargestellten Heterocyclen (dme)2LiOE2′ (E′ = S, 11a; E′ = Se, 11b). Reactive E = C(pp)π-Systems. XLII [1]. Novel Coordination Compounds of 2-(Diisopropylamino)-1-phosphaethyne: [{η4-(iPr2NCP)2}Ni{η2-(iPr2NCP)}], [(Ph3P)2Pt{η2-(iPr2NCP)}], and [Co2(CO)6{η2-μ2-(iPr2NCP)}] 2-(Diisopropylamino)-phosphaethyne iPr2NCP (2) reacts with the Ni(0)-complexes [Ni(1,5-cyclooctadiene)2] and [Ni(CO)3(1-azabicyclo[2.2.2]octane)], respectively, to give the novel complex [{η4-(iPr2NCP)2}Ni{η2-(iPr2NCP)}] (5), with the 1,3-diphosphacyclobutadiene derivative and 2 (side-on) as π-ligands. The molecular structure of 5 determined by X-ray diffraction on single crystals proves the spin systems and rotational barriers deduced from NMR-data (1H, 13C-, 31P). The PC distances of the four-membered ring of 1.817(2) and 1.818(2) A – as expected – are considerably longer than the PC bond of the η2-coordinated phosphaalkyne 2 [1.671(2) A]. – In the reactions of 2 with [(Ph3P)2Pt(C2H4)] or [Co2(CO)8] the ligand properties of 2 resemble those of alkynes affording the complexes [(Ph3P)2Pt{η2-(iPr2NCP)}] (7) with side-on coordinated 2 and [Co2(CO)6{η2-μ2-(iPr2NCP)}] with 2 acting as a 4e donor bridge in quantitative yield. In attempts to prepare copper(I) complexes of the aminophosphaalkyne 2 by reaction with CuCl or CuI the only isolable product formed in reasonable amounts under the influence of air and moisture is the 1 λ3, 3 λ5-diphosphetene (iPr2N) (10) (isolated yield: ca. 20%). The crystal structure analysis of 10 indicates a strong structural relationship to the diamino-2-phosphaallyl cation [Me(iPr2N)]+ (12), the 1,3-diphosphacyclobutadiene ligand (iPr2NCP)2 in the binuclear complex [{η1, μ2-(iPr2NCP)2}Ni2(CO)6] (3a) as well as to the heterocycles (dme)2LiOE2′ (E′ = S, 11a; E′ = Se, 11b) prepared by Becker et al. [11b, 35].

Journal ArticleDOI
TL;DR: In this article, the reaction of the (diisopropylamino)phosphaethyne (1) with diazo compounds of the type R1R2C=N2 (2a-2c) unexpectedly leads in high yields (60-90%) to the 1-aza-3,4-diphospholene derivatives 3a-3c, a new class of heterocycles.
Abstract: The reaction of the (diisopropylamino)phosphaethyne (1) with diazo compounds of the type R1R2C=N2 (2a–2c) unexpectedly leads in high yields (60–90%) to the 1-aza-3,4-diphospholene derivatives 3a–3c, a new class of heterocycles. NMR investigations of the analogous reaction of 1 with diazocyclopentadiene 2d show that the multi-step formation of 3a–3c proceeds via the 1-aza-3,4-diphospholes 6a–6d as intermediates.


Patent
20 Aug 1996
TL;DR: In this paper, the process for the manufacture of manganous catalytically active polyoxometalates of formula (1) (Q)q (MnpAaXxYyMmOdZz(H2O)b) c H2O and the process of the manufacture thereof is described.
Abstract: Manganiferous catalytically active polyoxometalates of formula (1) (Q)q (MnpAaXxYyMmOdZz(H2O)b) c H2O and the process for the manufacture thereof. In formula (I), Q, A, X, Y, M, Z, q, p, a, x, y, m, z, d, b and c have the following meaning: Q represents one or more cations selected from the group H, Li, K, Na, Rb, Cs, Ca, Mg, Sr, Ba, Al, PR?1R2R3R4 and NR1R2R3R4 with R1, R2, R3 et R4? representing H or C?1?-C20-alkyl, C5-C8-cycloalkyl or aryl; subscript q falls in a range of 1 to 60, more especially in a range of 1 to 40 and, in the case of a single-value counter-cation, also describes the charge on the anionic unit; Mn is manganese; subscript p falls in a range of 0.1 to 10, A is a heterometal and represents one or more transitional metals of the 2?nd to 8th? subsidiary groups except for Zn, especially Ru, V, Ti, Zr, Cr, Fe, Co, Cu, Sn, Ni, Re or Os; subscript a falls in a range of 0 to 10; X represents one or more elements selected from the group Ga, B, P, Si, Ge, As, F, Cl, Br and J; subscript x falls in the range of 0 to 10; Y represents Sb, S, Se, Te or Bi; subscript y falls in the range of 0.1 to 10; M represents one or more transition metals selected from the group Mo, W, Nb, Ta and V; subscript m falls in the range of 0.5 to 60; Z represents one or more anions selected from the group OH?-, F-, Cl-, Br-, I-, N?3-, NO3-, ClO4-, NCS-, SCN-, PF?6?-, RSO3-, RSO4-, CF3SO3-, BR4-, BF4-, OAc- with R = H, C?1?-C20-alkyl, C5-C8-cycloalkyl or aryl; subscript z falls in the range 0 to 10; subscript d represents the number of oxygen atoms necessary to balance the charge and b and c are numbers in the range 0 to 50. The oxidisation catalysts described are particularly good for activating peroxide compounds and oxygen.

Journal ArticleDOI
TL;DR: In this article, the structure of Re2O7(OH2)2 · 2(1,4-Dioxan) was characterized from a complete X-ray single-crystal structure analysis.
Abstract: Durch Solvolyse des polymeren Re2O7 mit 1,4-Dioxan entstehen in Gegenwart von geringen Mengen H2O zwei Produkte mit den Zusammensetzungen Re2O6(OH)2 · 3(1,4-Dioxan) (1) und Re2O7 · 2H2O · 2(1,4-Dioxan) (2). Durch eine Rontgenstrukturanalyse konnte nun 2, das als Edukt zur Synthese von reinem ReO3 wichtig ist, strukturell charakterisiert werden. Die kristalline Phase ist als Re2O7(OH2)2 · 2(1,4-Dioxan) zu formulieren und enthalt im Gegensatz zu 1 kein an Rhenium koordiniertes 1,4-Dioxan; sie besteht aus einer supramolekularen Anordnung von Re2O7(OH2)2-Einheiten wie in der „festen Perrheniumsaure” und uber OH … O-Wasserstoffbrucken gebundenen 1,4-Dioxan-Molekulen. In Analogie zum Dirheniumheptoxid und der festen Perrheniumsaure ist eines der Rheniumatome tetraedrisch, das andere verzerrt-oktaedrisch koordiniert. Reaction of Rhenium(VII) Oxide with 1,4-Dioxane – Crystal Structure of Re2O7(OH2)2 · 2(1,4-Dioxane) By solvolysis of polymeric Re2O7 with 1,4-dioxane in the presence of small amounts of H2O two products of compositions Re2O6(OH)2 · 3(1,4-dioxane) (1) and Re2O7 · 2H2O · 2(1,4-dioxane) (2) are formed. From a complete X-ray single-crystal structure analysis 2 could now be characterized structurally (monoclinic, space group P21/c, a = 6.828(3) A, b = 9.530(2) A, c = 26.421(8) A, β = 91.71(3)°, Z = 4). The compound is important as a convenient precursor for the preparation of pure rhenium trioxide. It is to be formulated as Re2O7(OH2)2 · 2(1,4-dioxane) and contains, contrary to 1, no 1,4-dioxane coordinated to Re. The crystalline phase consists of a supramolecular arrangement of Re2O7(OH2)2 units as in “solid perrhenic acid” and of 1,4-dioxane molecules associated through OH … O hydrogen bridges. Analogous to dirhenium heptoxide and to solid perrhenic acid one of the rhenium atoms is in tetrahedral, the other is in distorted octahedral coordination.

Patent
20 Aug 1996
TL;DR: In this paper, a manganese-containing polyoxometallates of the formula (1) (Q) (m.m O.sub.q (Mn.sub p, a, x, y, m, d, z and the numbers b and c are defined in the specification).
Abstract: The invention is directed to manganese-containing polyoxometallates of the formula (1) (Q).sub.q (Mn.sub.p A.sub.a X.sub.x Y.sub.y M.sub.m O.sub.d Z.sub.z (H 2 O) b )cH 2 O (1) where Q is one or more cations selected from the group consisting of H, Li, K, Na, Rb, Cs, Ca, Mg, Sr, Ba, Al, PR 1 R 2 R 3 R 4 and NR 1 R 2 R 3 R 4 where R 1 , R 2 , R 3 and R 4 =H or C 1 -C 20 -alkyl, C 5 -C 8 -cycloalkyl or aryl; Mn is manganese; A is a heterometal and is one or more transition metals from transition groups II to VIII apart from Zn, in particular Ru, V, Ti, Zr, Cr, Fe, Co, Cu, Sn, Ni, Re or Os; X is one or more elements selected from the group consisting of Ga, B, P, Si, Ge, As, F, Cl, Br and I; Y is Sb, S, Te, Se and Bi; M is one or more transition metals selected from the group consisting of Mo, W, Nb, Ta and V; Z is one or more anions selected from the group consisting of OH - , F - , Cl - , Br - , I - , N 3 - , NO 3 - , ClO 4 - , NCS--, SCN--, PF 6 - , RSO 3 - , RSO 4 - , CF 3 SO 3 - , BR 4 - , BF 4 - , OAc - , where R=H, C 1 -C 20 -alkyl, C 5 -C 8 -cycloalkyl or aryl. The indexes q, p, a, x, y, m, d, z and the numbers b and c are defined in the specification. The oxidation catalyst according to the invention is particularly effective in activating peroxidic compounds and oxygen.


Patent
14 Aug 1996
TL;DR: Bleichmittelzusammensetzung enthaltend ein oder mehrere Bleichmittels und einen odermehrer Polyoxometallate der Formel as discussed by the authors, wobei die Symbole Q, A, X, M, Z, q, a, x, m, y, z, b and c die in der Beschreibung genannten Bedeutung haben.
Abstract: Bleichmittelzusammensetzung enthaltend ein oder mehrere Bleichmittel und einen oder mehrere Polyoxometallate der Formel (Q) q (A a X x M m O y Z z (H 2 O) b ·cH 2 O als Bleichkatalysator, wobei die Symbole Q, A, X, M, Z, q, a, x, m, y, z, b und c die in der Beschreibung genannten Bedeutung haben.