Search Results - (Author, Cooperation:U. Baumeister)

2011-03-12

American Association for the Advancement of Science (AAAS)

0036-8075

1095-9203

Biology

Chemistry and Pharmacology

Computer Science

Medicine

Natural Sciences in General

Physics

0020-1693

Elsevier Journal Backfiles on ScienceDirect 1907 - 2002

Chemistry and Pharmacology

Electronic Resource

0040-4020

Elsevier Journal Backfiles on ScienceDirect 1907 - 2002

Chemistry and Pharmacology

Electronic Resource

0022-328X

Elsevier Journal Backfiles on ScienceDirect 1907 - 2002

Chemistry and Pharmacology

Electronic Resource

0277-5387

Elsevier Journal Backfiles on ScienceDirect 1907 - 2002

Chemistry and Pharmacology

Electronic Resource

0277-5387

Elsevier Journal Backfiles on ScienceDirect 1907 - 2002

Chemistry and Pharmacology

Electronic Resource

1432-0711

Springer Online Journal Archives 1860-2000

Medicine

Electronic Resource

0021-8383

Chemistry ; Organic Chemistry

Wiley InterScience Backfile Collection 1832-2000

Chemistry and Pharmacology

On the Conformational Behaviour of Substituted Phenylbenzoates - Molecular and Crystal Structure of the Nematogenic Compound 4′-(ß-Cyanoethyl)-phenyl-4-n-pentoxybenzoateThe title compound crystallizes in the monoclinic space group P21/n with a = 1567.6(2) pm, b = 915.5(1) pm, c = 1459.1(1) pm, β = 115.30(1)°, and four molecules per unit cell. The structure has been solved by direct methods and refined to R = 0.104. The molecules adopt a markedly stretched form and show a parallel arrangement of their long axes in the crystal lattice. The molecular and crystal structure is discussed in relation to the mesomorphic behaviour of the compound.A theoretical conformational analysis has been performed for the isolated phenylbenzoate molecule using the EPEN/2 method, its results are compared with the experimental torsion angles in a series of substituted phenylbenzoates.

6 Ill.

Electronic Resource

0941-1216

Chemistry ; Organic Chemistry

Wiley InterScience Backfile Collection 1832-2000

Chemistry and Pharmacology

Reaction of Bisvinamidinium Salts of 1,1-Dioxo-1,2-thiazine-6-aldehydes with Hydroxylamine to Substituted Pyrido[4,3-e]-1,2-thiazine-1,1-dioxidesBerichtigung der Struktur vom Typ 3 in [2]The formylation of 2-aryl-3,5-dimethyl-1,1-dioxo-1,2-thiazines with POCl3/DMF leads to the thiazine-6-aldehydes 1 and to the bis-vinamidinium salts 2. The reaction of 2a,b with hydroxylamine results in the formation of the pyrido-thiazine-N-oxides 5a,b, which give with PCl3 the 5-cyano-3-isoxazol-4-yl-pyrido[4,3-e]thiazines 6a,b. The pyridothiazines 9a and 10a are obtained by base-induced opening of the isoxazolyl-ring in 5a and 7a to the cyanoformylmethyl group. The compounds 6a and 7a were characterized by X-ray structure analysis.

1 Ill.

Electronic Resource

0941-1216

Chemistry ; Organic Chemistry

Wiley InterScience Backfile Collection 1832-2000

Chemistry and Pharmacology

As masked 1,3-dicarbonyl compounds, 1,1-dioxo-2H-1,2-thiazine-4-carbaldehydes (2a-e, 7) undergo ring transformations with nucleophilic hydrazines to produce 4-[1-methyl-2-(arylsulfamoyl)vinyl]pyrazoles (9a-i). For 9h, an X-ray structural analysis is reported. With less nucleophilic semicarbazide and p-nitrophenylhydrazine the hydrazones (11a, b) were isolated. The carbaldehydes 2a-e, 7 and 8a, b were synthesized by formylation of the 1,1-dioxo-2H-1,2-thiazines 1a-e, 5 and 6a, b with dichloromethyl methyl ether/TiCl4. In the case of 1a-e mixtures of 4- and 6-carbaldehydes (2a-e/3a-e) were obtained, which, however, could be used for the synthesis of pyrazoles.

4 Tab.

Electronic Resource

0941-1216

Chemistry ; Organic Chemistry

Wiley InterScience Backfile Collection 1832-2000

Chemistry and Pharmacology

Using benzenehexathiolate 1 it is possible to synthesize alkylthio-substituted benzo-1,3-dithiole-2-thiones 2, or -ones 3 and benzo-di(1,3-dithiole-2-thiones) 4, or -ones 5, resp., which were cleaved under basic conditions. The generated benzene-1,2-dithiolates 7 were isolated as benzene-dithiolato zincates 8, benzene-1,2-dithioles 11, and benzene-1-thiole-2-thiolates 10. Dibenzo[c,g](1,2,5,6)-tetrathiocins 9 were synthesized by oxidation of 7 or 8 in good yields. For the per(methylthio)-substituted tetrathiocin 9a the twist conformation was proved by x-ray structure analysis.The tetrathiocin 9a was probably formed via the orthodithiobenzoquinone 13a. Photolysis of 3a at room temperature in solution led to 9a and tetrakis(methylthio)benzo[c] (1,2,3)trithiole 12a as the main product, which was also formed by irradiation of 9a. The trithioles 12 were formed from 8 by reaction with sulfur dichloride. 12a was investigated by x-ray structure analysis. ortho-Dithiobenzoquinone 13c can be claimed as an intermediate upon irradiation of benzo-1,3-dithiol-2-one 3c in an argon matrix at 10 K. Depending on the wavelength the equilibrium lies either on the side of dithiobenzoquinone 13c or benzodithiete 14c. The same is true for system 15/16, which can be reached by flash vacuum pyrolysis of 3c.

Alkylthiosubstituted Bis(benzene-1,2-dithiolato)zincates, Benzene-1,2-dithioles, and -1,2-dithiolates - Educts for Dibenzo[c,g](1,2,5,6)tetrathiocins, and Benzo[c](1,2,3)trithioles; Investigations on Benzodithietes and ortho-Dithiobenzochinones

3 Ill.

Electronic Resource

0044-2313

Chemistry ; Inorganic Chemistry

Wiley InterScience Backfile Collection 1832-2000

Chemistry and Pharmacology

Synthesis and Molecular Structure Investigations of cis-2,6-Di-tert.-butyl-dibenzo[d, g]-[1,3,2,6]dioxadiphosphocin-2,6-disulfideThe reaction of t-butyl-bis-(o-hydroxyphenyl)phosphine, ButP(o-C6H4OH)2 with t-butyldichlorophosphine followed by the treatment with sulfur leads to the title compound 2 which is characterized by 1H, 13C and 31P NMR spectroscopy. The trans compound has not been observed. 2 crystallizes in the triclinic space group P1 with the unit cell parameters a 929.19(8), b 933.33(8), c 1357.7(2) pm, α 101.066(8)°, β 102.367(8)°, γ 104.320(7)°, V 1076.4(2) · 106 pm3, Z = 2. The molecule exist in a boat-chair conformation.

Die Reaktion von t-Butyl-bis-(o-hydroxyphenyl)phosphin, ButP(o-C6H4OH)2 und t-Butyldichlorphosphin liefert nach Umsetzung mit Schwefel die Titelverbindung 2, die gemäß 1H-, 13C- und 31P-NMR-spektroskopischer Studien als cis-Verbindung vorliegt. Die trans-Verbindung konnte nicht nachgewiesen werden. 2 kristallisiert in der triklinen Raumgruppe P1mit den Gitterkonstanten a 929,19(8), b 933,33(8), c 1357,7(2) pm, α 101,066(8)°, β 102,367(8)°, γ 104,320(7)°, V 1076,4(2) · 106 pm3, Z = 2. Das Molekül liegt in einer Wanne-Sessel-Konformation vor.

4 Ill.

Electronic Resource

0044-2313

Chemistry ; Inorganic Chemistry

Wiley InterScience Backfile Collection 1832-2000

Chemistry and Pharmacology

Structure and Reactivity of Stannylated Propyl Amines and Propyl Sulfides. Crystal and Molecular Structure of Bis(3-chlorodimethylstannylpropyl)sulfide S(CH2CH2CH2SnMe2Cl)2The synthesis and reactivity of stannylated propyl amines and propyl sulfides, respectively, E(CH2CH2CH2SnMe3)2 (1, E = NMe; 2 E = S) and N(CH2CH2CH2SnMe3)3 3 are reported. 1 and 3 react with dimethyl dichlorostannane under thermal cyclisation to 1,5-dimethyl-5-chloro-1aza-5-stannabicyclo[3.3.01,5]octane Me(Cl)Sn(CH2CH2CH2)2NMe 4 and 5-chloro-1-aza-5-stannatricyclo[3.3.3.01,5]-undecane ClSn(CH2CH2CH2)3N 5, respectively. The reaction of 2 with dimethyl dichlorostannane leads to the formation of bis(3-chloro-dimethylstannylpropyl)sulfide S(CH2CH2CH2SnMe2Cl)2 6, whereas the treatment of 2 with tin tetrachloride yields the bis(3-di-chloro-methylstannylpropyl)sulfide S(CH2CH2CH2SnMeCl2)2 7. The 1H, 13C, and 119Sn NMR data are discussed. 6 crystallizes in the ortho-rhombic space group Pna21 with the unit cell parameters a = 2275.0(1), b = 733.6(2), c = 1062.0(4) pm, V = 1.77273 nm3, Z = 4. The structure was refined to a final R value of 0.041. Both tin atoms adopt distorted trigonal bipyramidal configurations as a result of intramolecular interactions with the bridging sulphur. The sulphur and the chlorine atoms occupy the apical positions. The Sn—S distances amount to 309.7(4) and 311.8(4) pm.

Es wird über die Darstellung und Reaktivität der stannylierten Propylamine bzw. -sulfide E(CH2CH2CH2SnMe3)2 (1, E = NMe; 2, E = S) und N(CH2CH2CH2SnMe3)3 3 berichtet. 1 und 3 reagieren mit Dimethyldichlorstannan unter thermischer Cyclisierung zum 1,5-Dimethyl-5-chloro-1aza-5-stannabicyclo[3.3.01,5]-octan Me(Cl)Sn(CH2CH2CH2)2NMe 4bzw. 5-Chloro-1-aza-5-stannatricyclo[3.3.3.01,5]undecan ClSn(CH2CH2CH2)3N 5. Die Umsetzung von 2 mit Die Umsetzung von 2 mit Dimethyldichlorstannan führt dagegen zum Bis(3-chlorodimethyl-stannylpropyl)sulfid S(CH2CH2CH2SnMe2Cl)2 6, wogegen mit Zinntetrachlorid das Bis(3-dichlormethylstannylpropyl)-sulfid S(CH2CH2CH2SnMeCl2)2 7 resultiert. Die 1H-, 13C- und 119Sn-NMR-Daten werden diskutiert. 6 kristallisiert in der orthorhombischen Raumgruppe Pna21 mit den Gitterkonstanten a = 2275,0(1), b = 733,6(2), c = 1062,0(4) pm, V = 1,77273 nm3, Z = 4. Die Struktur wurde bis zu einem R-Wert von 0,041 verfeinert. Die Zinnatome sind durch intramolekulare Wechselwirkungen mit dem verbrückenden Schwefel jeweils verzerrt trigonal-bipyramidal konfiguriert, der Schwefel und die Chloratome besetzen die apicalen Positionen. Die Sn—S-Abstände betragen 309,7(4) und 311,8(4) pm.

2 Ill.

Electronic Resource

0044-2313

Complex compounds ; crystal structure ; Chemistry ; Inorganic Chemistry

Wiley InterScience Backfile Collection 1832-2000

Chemistry and Pharmacology

Synthesis, Crystal Structures and Spectroscopic Investigations of 3d-Transition Metal Complexes with Bicyclo[2.2.1]hept-5-ene-2-endo,3-cis-dicarboxylic Acid and N,N-Donor LigandsThe synthesis of coordination compounds of the general type [MLdam(H2O)3] · 2.5 H2O with M = Mn2+, Co2+, Ni2+; H2L = bicyclo[2.2.1]hept-5-ene-2-endo,3-cis-dicarboxylic acid and dam = 2,2′-dipyridyl, 1,10-phenanthroline has been described. The complexes have been characterized by elementary analysis, infrared and electronic spectra and magnetic susceptibility measurements.The results of X-ray crystal structure analyses of [MnLdipy(H2O)3] · 2.5 H2O (1 a) and [CoLdipy(H2O)3] · 2,5 H2O (1 b) show, that both compounds crystallize isotypically and prove the octahedral coordination of the metal atoms. The dicarboxylate anion is coordinated to the central atom by an O atom of only one carboxylate group, the other one is in the ionic state. One O atom of each carboxylate group makes an intramolecular hydrogen bond with a water molecule of the coordination sphere. The other crystal water molecules form a network of H bonds one with another and with the complex molecules, thus stabilizing the crystal packing.

Die Synthese von Koordinationsverbindungen der allgemeinen Zusammensetzung [MLdam(H2O)3] · 2,5 H2O mit M = Mn2+, Co2+, Ni2+; H2L = Bicyclo[2.2.1]hept-5-en-2-endo,3-cis-dicarbonsäure und dam = 2,2′-Dipyridyl, 1,10-Phenanthrolin wird beschrieben. Die Komplexe werden durch quantitative Analysen, IR- und Elektronenspektren sowie Magnetmessungen charakterisiert.Die Ergebnisse der Röntgenkristallstrukturanalyse von [MnLdipy(H2O)3] · 2,5 H2O (1 a) und [CoLdipy(H2O)3] · 2,5 H2O (1 b) zeigen, daß beide Verbindungen isotyp kristallisieren und belegen die oktaedrische Koordination der Metallatome. Das Dicarboxylat-Anion ist mit nur einem O-Atom am Zentralatom gebunden, die zweite Carboxylatgruppe liegt ionisch vor. Je ein O-Atom jeder Carboxylatgruppe geht eine intramolekulare Wasserstoffbrückenbindung mit einem koordinativ gebundenem Wassermolekül ein. Die restlichen Kristallwassermoleküle bilden ein die Packung stabilisierendes Wasserstoffbrückennetz untereinander und mit den Komplexmolekülen.

3 Ill.

Electronic Resource

0044-2313

Nickel(0) complexes ; isocyanide ligands ; Chemistry ; Inorganic Chemistry

Wiley InterScience Backfile Collection 1832-2000

Chemistry and Pharmacology

Triphenylphosphane Nickel(0) Complexes with Isocyanide Ligands  -  [(RNC)nNi(PPh3)4-n] (n = 1-3)Synthesis and properties of the isocyanide triphenylphosphane nickel(0) complexes [(RNC)Ni(PPh3)3], [(RNC)2Ni(PPh3)2] and [(RNC)3Ni(PPh3)] (R = tBu, Cy, PhCH2, p-TosCH2) are described. I.r. and 31P n.m.r. spectra were recorded and the X-ray crystal structure of [(PhCH2NC)2Ni(PPh3)2] was determined.

Synthese und Eigenschaften von Isocyanid-Triphenylphosphan-Nickel(0)-Komplexen der Typen [(RNC)Ni(PPh3)3], [(RNC)2Ni(PPh3)2] und [(RNC)3Ni(PPh3)] (R = tBu, Cy, PhCH2, p-TosCH2) werden beschrieben.Die Charakterisierung der genannten Komplexe erfolgte mit Hilfe der IR- und 31P-NMR-Spektroskopie, von [(PhCH2NC)2Ni(PPh3)2] wurde die Molekülstruktur bestimmt.

1 Ill.

Electronic Resource

0044-2313

Nickel(0) complexes ; sulfur dioxide complexes ; N-p-tolylsulfinylamine complexes ; isocyanide ligands ; Chemistry ; Inorganic Chemistry

Wiley InterScience Backfile Collection 1832-2000

Chemistry and Pharmacology

Sulfur Dioxide as Ligand and Synthon. XIII. Reactions of Isocyanide-tris(triphenylphosphane)nickel(0) Complexes with Sulfur Dioxide and N-p-tolylsulfinylamineReactions of the isocyanide-tris(triphenylphosphane)-nickel(0) complexes [(RNC)Ni(PPh3)3] (R = tBu, Cy, PhCH2, p-TosCH2) with SO2 and p-TolNSO are described. The sulfur dioxide and N-p-tolylsulfinylamine complexes obtained by PPh3 ligand substitution have been characterized by means of i.r. and 31P n.m.r. spectra. The X-ray crystal structure of [(Ph3P)2(CyNC)Ni(SO2)] · 0.5 PhMe and (Ph3P)(tBuNC)Ni(η2-p-TolNSO) have been determined.

Reaktionen der Isocyanid-tris(triphenylphosphan)-nickel(0)-Komplexe [(RNC)Ni(PPh3)3] (R = tBu, Cy, PhCH2, p-TosCH2) mit SO2 und p-TolNSO werden beschrieben. Die Charakterisierung der durch PPh3-Ligandensubstitution resultierenden Schwefeldioxid- sowie N-p-Tolylsulfinylamin-Komplexe erfolgte mit Hilfe der IR- und 31P-NMR-Spektroskopie. Für [(Ph3P)2(CyNC)Ni(SO2)] · 0,5 PhMe und (Ph3P) · (tBuNC)Ni(η2-p-TolNSO) wurden die Kristallstrukturen bestimmt.

7 Tab.

Electronic Resource

0044-2313

Lanthanoid(III) carboxylate complexes ; synthesis ; crystal structure ; IR spectra ; thermal decomposition ; Chemistry ; Inorganic Chemistry

Wiley InterScience Backfile Collection 1832-2000

Chemistry and Pharmacology

Synthesis, Crystal Structures, and Properties of Lanthanoid(III) Complexes with 7-Oxa-bicyclo[2.2.1]heptane-2,3-dicarboxylic AcidThe synthesis of coordination compounds [ML(HL)(H2O)] with M = La3+, Ce3+, Pr3+, Nd3+ and H2L = 7-oxa-bicyclo[2.2.1]heptane-2-exo,3-cis-dicarboxylic acid (1) has been described. Results of IR spectroscopy and thermal decomposition are given. As a result of X-ray analyses, the four investigated lanthanoid(III) complexes are isotypic. Their stereochemistry approximates to the tri-capped trigonal prism with nine O atoms coordinating the metal atom. The bicyclic ligand acts as a tridentate chelating monoanion HL- as well as a pentadentate dianion L2- with both chelating and bridging function. One coordination place at the metal atom is occupied by a water molecule.

Die Synthese der Koordinationsverbindungen [ML(HL)(H2O)] mit M = La3+, Ce3+, Pr3+ und Nd3+ und H2L = 7-Oxa-bicyclo[2.2.1]heptan-2-exo,3-cis-dicarbonsäure (1) wird beschrieben. Ergebnisse der IR-Spektroskopie und thermoanalytischer Untersuchungen werden mitgeteilt. Nach den Ergebnissen von Röntgenkristallstrukturanalysen sind die vier untersuchten Lanthanoid(III)-Komplexe isotyp. In ihnen ist das Metallatom in dreifach überkappter trigonal-prismatischer Koordination von neun O-Atomen als nächsten Nachbarn umgeben. Dabei tritt der bicyclische Ligand einmal als dreizähniges Monoanion HL- und zum anderen als fünfzähniges Dianion L2- mit Brückenfunktion auf. Die neunte Koordinationsstelle wird von einem Wassermolekül besetzt.

5 Ill.

Electronic Resource

0044-2313

Organonickel(II) complexes ; SO2 coordination ; IR photoacoustic spectroscopy ; X-ray crystal structure of [NiBr{C6H3(CH2NR1R2)2-2,6}] ; Chemistry ; Inorganic Chemistry

Wiley InterScience Backfile Collection 1832-2000

Chemistry and Pharmacology

Sulfur Dioxide as Ligand and Synthon. XII. Synthesis and Reaction Behaviour of Nickel(II) Complexes with Terdendate Anionic Ligands of the Type (C6H3{CH2NR1R2}2-2,6)-Organonickel(II) complexes of the type [NiX{C6H3(CH2NR1R2)2-2,6}] (X = halide OH2+/CF3SO3-; R1=R2=Et 1; R1=R2=i—Pr 2; R1 = Me, R2 = Cy 3; (NR1R2) = piperidino 4; (NR1R2) = pyrrolidino 5) are described. 1H and 13C NMR and UV/Vis spectra were recorded, and the X-ray crystal structure of 1 a (X = Br) was determined. This complex crystallizes orthorhombically in the space group Pbca with a = 1 335.8(2) pm, b = 1 903.3(3) pm, c = 1 365.4(3) pm and Z = 8, and has an approximately square-planar geometry. 4 and 5 show a reversible binding of SO2 which has been detected by means of IR photoacoustic spectroscopy. The reactions of 1-5 with CS2 and PhNSO are discussed.

Organonickel(II)-Komplexe des Typs [NiX{C6H3(CH2NR1R2)2-2,6}] (X = Halogen, OH2+/CF3SO3-; R1=R2=Et 1; R1=R2=i—Pr 2; R1 = Me, R2 = Cy 3; (NR1R2) = piperidino 4; (NR1R2) = pyrrolidino 5) werden beschrieben. Die Charakterisierung erfolgte mit Hilfe der 1H— und 13C-NMR- sowie der UV/Vis-Spektroskopie. Von 1 a (X = Br) wurde die Kristallstruktur bestimmt. Dieser Komplex kristallisiert orthorhombisch in der Raumgruppe Pbca mit a = 1 335,8(2) pm, b = 1 903,3(3) pm, c = 1 365,4(3) pm und Z = 8, er besitzt eine annähernd quadratisch-planare Geometrie. 4 und 5 vermögen SO2 reversibel zu fixieren, was durch die IR-Photoakustik-Spektroskopie nachweisbar ist. Die Reaktionen von 1-5 mit CS2 und PhNSO werden diskutiert.

5 Ill.

Electronic Resource

0044-2313

Chemistry ; Inorganic Chemistry

Wiley InterScience Backfile Collection 1832-2000

Chemistry and Pharmacology

Crystal and Molecular Structure of Bis[1,2-bis(diphenylphosphino)ethane]nickel(O)The title compound [Ni(dppe)2] (dppe = Ph2PCH2CH2PPh2) crystallizes in the monoclinic space group P21/n with lattice parameters a = 983.2(2), b = 2119.2(3), c = 2145.1(4) pm, β = 91.97(1)°, and a unit cell contents of four molecules. The structure was solved by heavy atom method and refined to an R-value of 0.063 (RW = 0.052), using 2779 observed unique reflexions. The Ni atom as the spiro centre is distorted-tetrahedrally coordinated by the four P atoms of the two bidentate chelating ligands. The Ni—P bond lengths are very similar with a mean value of 216(1) pm. The mean value of Tolman's cone angle for the dppe ligand calculated from the molecular structure of [Ni(dppe)2] amounts to 129.8°.

Die Titelverbindung [Ni(dppe)2] (dppe = Ph2PCH2CH2PPh2) kristallisiert in der monoklinen Raumgruppe P21/n mit den Gitterkonstanten a = 983,2(2), b = 2119,2(3), c = 2145,1(4) pm, β = 91,97(1)° und vier Molekülen pro Elementarzelle. Die Struktur wurde auf der Grundlage von 2779 beobachteten symmetrieunabhängigen Reflexintensitäten nach der Schweratommethode gelöst und bis zu einem R-Wert von 0,063 (RW = 0,052) verfeinert. Das Ni-Atom als Spirozentrum ist verzerrt tetraedrisch von den vier P-Atomen der beiden zweizähnigen Chelatliganden umgeben. Die sehr ähnlichen Ni-P-Abstände weisen einen Mittelwert von 216(1) pm auf. Der aus der Molekülstruktur von [Ni(dppe)2] berechnete mittlere Öffnungswinkel für den Tolman-Kegel von dppe beträgt 129,8°.

2 Ill.

Electronic Resource

0044-2313

Manganese ; cobalt ; nickel ; copper carboxylate complexes ; crystal structure ; Chemistry ; Inorganic Chemistry

Wiley InterScience Backfile Collection 1832-2000

Chemistry and Pharmacology

Complex Formation of 5,6-Dihalogeno-7-oxa-bicyclo[2.2.1]heptane-2,3-dicarboxylic Acid with 3d Transition ElementsCarboxylate complexes of bivalent manganese, cobalt, nickel and copper with 5,6-dichloro- and 5,6-dibromo-7-oxa-bicyclo[2.2.1]heptane-2,3-dicarboxylic acid (3 and 4) have been prepared. For cobalt and nickel two types of complexes are formed: [ML3/4(H2O)3] · H2O and [ML3/4(H2O)2], the latter is thermodynamically more stable. Manganese and copper form only complexes [MnL3/4] and [CuL3/4(H2O)2], respectively. The stereochemical configuration of the compounds have been deduced from their spectroscopic and magnetic properties. The metal atoms have been found to be in an octahedral environment. The stability constants of the complexes have been determined by potentiometric measurements. The thermal decomposition of the complexes has been studied by thermogravimetry and differential thermal analysis. The complexes of 3 are thermally more stable than the corresponding ones of 4.The X-ray structure analysis of [CoL3(H2O)3] · H2O shows a monomeric structure of the complex within the crystal and an octahedral coordination of the metal ion. The dicarboxylate anion acts as a tridentate ligand, the other octahedral sites are occupied by three water molecules. The chlorine atoms are not involved in the network of hydrogen bonds within the crystal packing.

Es wurden Carboxylatkomplexe des zweiwertigen Mangans, Cobalts, Nickels und Kupfers mit der 5,6-Dichlor- und 5,6-Dibrom-7-oxa-bicyclo[2.2.1]heptan-2,3-dicarbonsäure (3 und 4) dargestellt. Dabei bilden sowohl Cobalt als auch Nickel zwei verschiedene Komplextypen [ML3/4(H2O)3] · H2O und [ML3/4(H2O)2] aus, wobei der letztere thermodynamisch stabiler ist. Für Mangan und Kupfer konnten dagegen nur Koordinationsverbindungen der Form [MnL3/4] bzw. [CuL3/4(H2O)2] erhalten werden. Die Ergebnisse spektroskopischer und magnetischer Messungen ließen in allen Fällen auf oktaedrische Koordinationsgeometrie schließen. Die Stabilitätskonstanten der Komplexe wurden durch potentiometrische Titration bestimmt. Die thermische Zersetzung der Verbindungen wurde mit TG-, DTG- und DTA-Methoden untersucht. Dabei erwiesen sich die Koordinationsverbindungen von 3 als thermisch stabiler als die entsprechenden von 4.Die Röntgenkristallstrukturanalyse von [CoL3(H2O)3] · H2O zeigt, daß der Komplex monomer im Kristall vorliegt und das Metallatom oktaedrisch koordiniert ist. Das Dicarboxylat-Anion fungiert als dreizähniger Chelatligand, die restlichen Oktaederplätze am Co-Atom werden von Wassermolekülen besetzt. Die Chloratome sind nicht am Wasserstoffbrückennetz im Kristallgitter beteiligt.

4 Ill.

Electronic Resource