Komplexe des zweiwertigen Molybdäns,Derivate des Oktahalodimolybdat(II)-Ions, 4. Mitt.: Darstellungen und Kristallstrukturen von zwei neutralen Komplexen mit 4-Methylpyridin

Mo₂Cl₄ Pic ₄·CHCl₃ (A) (Pic=4-methylpyridine) and Mo₂Br₄ Pic ₄ (B) crystallize in the monoclinic space group.A inC2/c (No. 15) witha=15.175 (4),b=10.847 (2),c=19.946 (6) and =104.52 (2)°;D _o=1.71 (2),D _c =1.72 gcm^–3 forZ=4.B inP2_l/n (No. 14) witha=9.270 (3),b=16.614 (5),c=9.305 (3) and =91.96 (5)°;D _o=2.03 (3),D _c =2.05 gcm^–3 forZ=2.Two halogens and 4-methylpyridines of the MoX ₂ Pic ₂ group are in the trans position. Mo–Mo bond lengths are 2.153 96) forA and 2.150 92) forB. Both molecules are situated on the inversion center resulting in the eclipsed configuration of the ligands around the molybdenum pair. The structure ofB has been refined to the conventionalR factors of 0.08 and 0.098. Disorder on the part of 4-methylpyridines and chloroform molecules stopped the refinement ofA at the endR value of 0.175.Mean Mo–X and Mo–N bonding distances are 2.40 (2), 2.25 (5) forA and 2.53 (3), 2.25 (1) forB.

     

Einfluß der Polarität und Viskosität des Lösungsmittels auf die Deaktivierung des S1-Zustandes von Donator-Akzeptor-substituiertentrans-Stilbenen

The dependence of the fluorescence constantsk _f ⁿ and the adiabatic twisting constantsk _tpof the S₁-State upon the solvent polarity, the capacity of hydrogen-bonding, as well as the solvent viscosity, were investigated for donor-acceptor substitutedtrans-stilbenes [4-dimethylamino-4-cyano-stilbene (1 g), 4-dimethylamino-4-diphenylphosphinyl-stilbene (1 b), 4-dimethylamino-4-brom-stilbene (1 h) and 4-dimethylamino-4-methoxistilbene (1 k)] by using the multiparameter model. An increase of the solvent polarity results in the decrease of the fluorescence ratek _f ⁿ for all these compounds. The specific interaction between the strongly polar stilbenes such as1 g and1 b and a solvent leads to additional decrease ink _f ⁿ but in the case of a relatively weak polar compound1 k to its growth. The linear combination of universal and specific solvent-solute interactions yields distinct relations fork _tp. Both interactions have an influence onk _tpfor1 g,1 b, and1 k to an equal degree. The twisting observed for1 g and1 b due to the interaction with solvent is hindered, however it is being supported for1 k. The influence of the investigated small range of viscosity onk _tpat simultaneous variable solvent polarity (pure solvent) is only visible for the weak polar1 k. In the other cases the effect of solvent-polarity is predominant.The viscosity dependence ofk _tpwas also experimentally proved for1 g,1 b and1 k by applying the obtained different dimethylformamid-acetonitril mixtures. According previous results the radiationless deactivation process is caused by twisting around ethyl-bonding, thereforek _tpevidently decreases with an increase of viscosity.

     

Spectrophotometric determination of mercury with 5,10,15,20-tetrakis(3-chloro-4-sulfophenyl)porphine by flow injection analysis

5,10,15,20-tetrakis(3-chloro-4-sulfophenyl)porphine (m-Cl-TPPS₄) was synthesized and used for the Spectrophotometric determination of mercury by flow injection analysis. A pseudo-first-order reaction kinetic mechanism was proposed with a rate constant of 0.8 min^–1 for Hg(II) withm-Cl-TPPS₄ in the presence of 8-hydroxyquinoline in a medium of 1.0M acetic acid and sodium acetate buffer solution (pH 6.22). In the optimum conditions of reaction temperature (85 ° C), stopped-flow time (60 s) and sampling volume (100 l), the method's relative standard deviation was 0.82% (n = 12) at 5.0 g ml^–1 mercury, with a linear range of 0–12.0 g ml^–1 and an analytical frequency of 60h^–1. The detection limit (3) was 0.025 g ml^–1. Interference studies showed that most metal ions co-existing with Hg²⁺ could be tolerated at 100-fold excess levels, but Zn²⁺, Cu²⁺ and Mn²⁺ needed to be masked. The method has been applied to the analysis of water samples with satisfactory results.     

Unsymmetrical dinuclear cobalt and nickel trimethylacetate complexes

The reaction of the dinuclear complex Co₂(-OOCCMe₃)₂(²-OOCCMe₃)₂bpy₂ (1) with the polymer [Co(OH) _n (OOCCMe₃)_2–n ] _x afforded the unsymmetrical dinuclear complex bpyCo₂(₂-O,²-OOCCMe₃)(₂-O,O"-OOCCMe₃)₂(²-OOCCMe₃) (2). The reaction of 2,2"-dipyridylamine with [Co(OH) _n (OOCCMe₃)_2–n ] _x gave rise to the analogous complex [(C₅H₄N)₂NH]Co₂(₂-O,²-OOCCMe₃)(-OOCCMe₃)₂(²-OOCCMe₃) (3). The reaction of complex 1 with Ni₄(₃-OH)₂(-OOCCMe₃)₄(OOCCMe₃)₂(MeCN)₂[²-o-C₆H₄(NH₂)(NHPh)]₂ (4) produced an isostructural heterometallic analog of complex 2 with composition bpyM₂(₂-O,²-OOCCMe₃)(₂-O,O"-OOCCMe₃)₂(²-OOCCMe₃) (5) (M = Co, Ni; Co : Ni = 1 : 1) and the dinuclear heterometallic complex bpy(HOOCCMe₃)M(-OH₂)(-OOCCMe₃)₂M(OOCCMe₃)₂[o-C₆H₄(NH₂)(NHPh)] (6) (M = Co, Ni; Co : Ni = 0.15 : 1.85). Compounds 2 and 5 exhibit ferromagnetic spin-spin exchange interactions.     

RPLC retention of 1,ω-di(alkoxy)-polysulphides

Summary A simple and reliable method for routine measurement of ammonia in ambient air is described. It is based on the collection of ammonia on H₃PO₃-coated annular denuders and its subsequent derivatization withm-toluoyl chloride (MTC) in alkaline acetonitrile. The resultingm-toluamide is determined by reversed phase HPLC with UV detection at 230 nm. The limit of dotection is about 0.3g m^–3 for NH₃ in air samples collected at 151 min^–1 for one hour.     

Colorimetric determination ofm-aminophenol

Summary Potassium iodate reacts withm-aminophenol in presence of sulfuric acid to give pink violet color having 5g as visual limit of identification. The color reaction is specific form-aminophenol;o-, andp-aminophenol do not interfere if their amount does not exceed 10 and 70% respectively. This provides a new colorimetric method for the determination ofm-aminophenol in small quantities.

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Zusammenfassung Kaliumjodat reagiert mit m-Aminophenol in Gegenwart von Schwefelsäure unter Bildung einer rosavioletten Farbe mit einer Erfassungsgrenze von 5g. Die Reaktion ist spezifisch; o- und p-Aminophenol stören nicht, sofern nicht mehr als 10 bzw. 70% anwesend sind. Daraus ergibt sich ein neues kolorimetrisches Verfahren zur Bestimmung kleiner Mengen m-Aminophenol.

     

Formation of cobalt(iii) cations with semiquinonediimine ligands

The reactions of polynuclear cobalt(ii) trimethylacetates [Co(OH) _n (OOCCMe₃)_2–n ] _x , Co₆(₃-OH)₂(OOCCMe₃)₁₀(HOOCCMe₃)₄, or Co₄(₃-OH)₂(OOCCMe₃)₆(HOEt)₆ with an excess of N-phenyl-o-phenylenediamine (1) in toluene followed by treatment with atmospheric oxygen afforded the diamagnetic complex [Co{²-(NPh)(NH)C₆H₄}₂{¹-(NH₂)C₆H₄(NPhH)}]⁺(Me₃CCOO...H...OOCCMe₃)^– (3), whose cation contains the Co^III atom. The reaction of Co₄(₃-OH)₂(OOCCMe₃)₆(HOEt)₆ with a deficient amount of diamine 1 in acetonitrile under an argon atmosphere gave rise to the antiferromagnetic ionic complex [Co{²-(NPh)(NH)C₆H₄}₂MeCN]⁺[Co₂(₂,²-OOCCMe₃)(₂-OOCCMe₃)₂(²-OOCCMe₃)₂]^–·2MeCN (4), whose cation is an isoelectronic analog of the cation in complex 3. The structures of the new compounds were established by X-ray diffraction analysis.     

Stereochemie von Metallocenen, 43. Mitt.: Torsionsisomere Biphenyl-tricarbonylchrom-Komplexe: Darstellung,Konformationsanalyse und Kinetik der Interkonversion

Complexation of methyl 3-nitro-2-(o-tolyl)-benzoate (2, ano-trisubstituted biphenyl) with hexacarbonyl chromium gave the isomeric Cr(CO)₃ complexes3 and4 both existing as two torsional isomersa andb, as seen by nmr. For the main product3 the preferred conformations of the two torsional isomersa andb were deduced by the lanthanide induced shift (LIS) technique. The activation energy for the interconversion process could be determined from kinetic measurements and especially from¹H-nmr coalescence temperature of the methylsignals. The barrier of 91±1.5 kJ/mol (21.7±0.3 kcal/mol) in3 reflects the interaction of theo-H-atom of the benzene ring passing the Cr(CO)₃ moiety of the benchrotrene ring during the interconversion.A partial optical resolution of3 was achieved by asymmetric reduction with a chiral lithium-aluminium hydride yielding (+)-3 with [] _D ²⁰ +30° (benzene) and the levorotatory alcohol (–)-7.

42. Mitt.:K. Schlögl undR. Schölm, Mh. Chem.109, 1227 (1978).     

Synthesis and X-ray crystal structure of [1,3-bis(η5-cyclopentadienyl)-1,1,3,3-tetramethyldisiloxane]hafnium(IV) dichloride

Summary The tetramethyldisiloxane-bridged hafnocene complex [HfCl₂{-(⁵-C₅H₄)SiMe₂OSiMe₂(²-C₅H₄)}] (1) has been prepared by the reaction of HfCl₄ with the dilithiatedbis(cyclopentadienyl)disiloxane (LiC₅H₄SiMe₂)₂O in a molar ratio of 1:2. The new compound was characterized by spectroscopic and X-ray diffraction methods. The crystals are monoclinic of space groupP2₁/c and isostructural with the corresponding complexes of titanium and zirconium. The unit cell dimensions area=13.51(1) Å,b=8.672(7) Å,c=15.41(1) Å, =97.15(2)°, andZ=4.

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Darstellung und Röntgenkristallstruktur von [1,3-Bis(⁵-cyclopentadienyl)-1,1,3,3-tetramethyldisiloxan]hafnium(IV)dichlorid

Zusammenfassung Der tetramethyldisiloxan-überbrückte Hafnocenkomplex [HfCl₂{-(⁵-C₅H₄)-SiMe₂OSiMe₂(²-C₅H₄)}] (1) wurde durch Umsetzung von HfCl₄ mit dem lithiiertenBis(cyclopentadienyl)disiloxan (LiC₅H₄SiMe₂)₂O im Molverhältnis 1:2 dargestellt. Die neue Verbindung wurde spektroskopisch und röntgenographisch charakterisiert. Sie kristallisiert in der monoklinen RaumgruppeP2₁/c und ist isostrukturell mit den entsprechenden Titan-und Zirkoniumkomplexen. Die Dimensionen der Einheitszelle sinda=13.51(1) Å,b=8.672(7) Å,c=15.41(1) Å, =97.15(2)° undZ=4.

     

Investigation of the colour reaction of phenols with MBTH,II: Properties of the isolated products of the reaction with phenol, 2,6-dimethylphenol and 4-methylphenol

The following model compounds for the study of the oxidative coupling reactions of 2-hydrazono-3-methylbenzothiazoline (MBTH) with phenolic compounds were prepared: thep-coupling products of the reagent with phenol and 2,6-xylenol and theo-coupling product withp-cresol. The proposed structure of the dyes was confirmed. In strongly polar and ionic media the azobetaine form of the products predominates, and in non-polar media the azine structure. The principal physico-chemical properties of the products were determined and the results contributed to formulation of the course of the coupling reaction, and to optimization of the conditions for determination of small amounts of phenolic substances. The violeto-coupling product is less stable than the redp-coupling products, and intramolecularly hydrogen-bonded six-membered ring is assumed to exist in the structure. In acid medium the dyes are mainly monoprotonated, and partly diprotonated in concentrated sulphuric acid medium. The products are stable up to about pH 11. These properties make extraction into low-polarity solvents possible. The dye derived from 2,6-xylenol andp-cresol has not hitherto been prepared. The principal spectral characteristics, _max(), of the products in ethanol medium are: 499 nm (4.7 × 10⁴ 1·mole^–1 cm^–1) for the phenol derivative, 486 nm (5.0 × 10⁴) for the 2,6-xylenol product, and _max 540 nm for thep-cresol product.Part I: Mikrochim. Acta [Wien]1977,I, 241     

Continuous-flow separation and pre-concentration coupled on-line to solid-surface fluorescence spectroscopy for the simultaneous determination of<Emphasis Type="Italic"> o</Emphasis>-phenylphenol and thiabendazole

A novel and single flow-injection system combined with solid-surface fluorescence detection is proposed in this work for the resolution of a mixture of two widely used pesticides (o-phenylphenol and thiabendazole). The continuous-flow methodology is based on the implementation of on-line pre-concentration and separation of both analytes on the surface of C₁₈ silica gel beads placed just inside the flow cell, implemented with gel-phase fluorimetric multi-wavelength detection (using 305/358 and 250/345 nm as excitation/emission wavelengths for thiabendazole and o-phenylphenol, respectively). The separation of the pesticides was possible owing to the different retention/desorption kinetics of their interactions with the solid support in the zone where the stream impinges on the solid material. No previous separation of the analytes before they reach the flow cell is needed thereby simplifying substantially both the procedure and the manifold. By using a sample volume of 2,600 L, the system was calibrated in the range 0.5–16 and 5–120 ng mL^–1 with detection limits of 0.09 and 0.60 ng mL^–1 for thiabendazole and o-phenylphenol, respectively. The RSD values (n=10) were about 1% for both analytes. The proposed methodology was applied to environmental water samples and also to various commercial pesticide formulations containing both analytes. Recovery percentages were 97–103% and 98–102% for thiabendazole and o-phenylphenol, respectively.     

Crystal structure and vibrational spectra of pyridine-2,6-dithio-carbomethylamide

The crystal structure of Pyridine-2,6-dithio-carbomethylamide (PDTA) is described: C₉H₁₁N₃S₂, monoclinic, P2₁/c,Z=4,a=6.000 (1) Å,b=8.840 (1) Å,c=21.452 (1) Å, =105.47 (1)^o,d _x=1.47 gcm^–3. The structure was solved with direct methods and refined to a conventionalR-factor of 0.047. The molecule is nearly planar in the crystal. There are possibly weak intramolecular H-bonds between the two amide nitrogens and the pyridine nitrogen and intermolecular H-bonds between two amide nitrogens and one thioamide sulfur atom. The IR andRaman spectra ofPDTA and deuteratedPDTA are discussed.

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Kristallstruktur und Schwingungsspektren von Pyridin-2,6-dithiocarbomethylamid

Zusammenfassung Die Kristallstruktur von Pyridin-2,6-dithiocarbomethylamid (PDTA) wurde bestimmt: C₉H₁₁N₃S₂, monoklin, P2₁/c,Z=4,a=6,000 (1) Å,b=8,840 (1) Å,c=21,452 (1) Å, =105,47 (1)^o,d _x=1,47 gcm^–3. Das Phasenproblem wurde mittels direkter Methoden gelöst und die Struktur bis zu einemR-Faktor vonR=0,047 verfeinert. Das Molekül ist im Kristall nahezu planar. Das Vorliegen schwacher intramolekularer Wasserstoffbrücken zwischen den beiden Thioamid-Stickstoffatomen und dem Pyridinstickstoff sowie intermolekularer Wasserstoffbrücken zwischen Thioamid-Stickstoff- und Thioamid-Schwefelatomen wird postuliert. IR- undRaman-Spektren vonPDTA und deuteriertemPDTA werden diskutiert.

     

Human urine certified reference material CZ 6010: creatinine and toluene metabolites (hippuric acid and o-cresol) and a benzene metabolite (phenol)

A reference material for the biological monitoring of occupational exposure to toluene, benzene and phenol was prepared. O-cresol and hippuric acid (metabolites of toluene) are used for the biological monitoring of occupational exposure to toluene. Phenol, a metabolite of benzene, is used for the biological monitoring of exposure to benzene, but phenol can of course also be used as an indicator of exposure to phenol as well. The reference material (RM) used for the determination of these metabolites was prepared by freeze-drying pooled urine samples obtained from healthy persons occupationally exposed to toluene and those taking part in an inhalation experiment. Tests for homogeneity and stability were performed by determining urine concentrations of o-cresol, hippuric acid, creatinine and phenol. To investigate the stability of the RM, the urinary concentrations of o-cresol and phenol were monitored for eighteen months using GC and HPLC, while those of hippuric acid and creatinine were followed for five and six years, respectively, using HPLC. Analysis of variance showed that the concentrations did not change. The certified concentration values (and their uncertainties) of the substances in this reference material (phenol concentration c=6.46±0.58 mg l⁻¹; o-cresol concentration c=1.17±0.15 mg l⁻¹; hippuric acid concentration c=1328±30 mg l⁻¹; creatinine concentration c=0.82±0.10 g l⁻¹) were evaluated via the interactive statistical programme IPECA.     

Rapid spectrofluorimetric determination of lisinopril in pharmaceutical tablets using sequential injection analysis

The present work reports for the first time a simple and rapid method for the spectrofluorimetric determination of lisinopril (LSP) in pharmaceutical formulations using sequential injection analysis (SIA). The method is based on reaction of LSP with o-phthalaldehyde (OPA) in the presence of 2-mercaptoethanol (borate buffer medium, pH=10.6). The emission of the derivative is monitored at 455 nm upon excitation at 346 nm. The various chemical and physical conditions that affected the reaction were studied. The calibration curve was linear in the range 0.3–10.0 mg L^–1 LSP, at a sampling rate of 60 injections h^–1. Consumption of OPA reagent was significantly reduced compared with conventional flow injection (FI) systems, because only 50 L of OPA was consumed per run. The method was found to be adequately precise (s_r=2% at 5 mg L^–1 LSP, n=10) and the 3 detection limit was 0.1 mg L^–1. The method was successfully applied to the analysis of two pharmaceutical formulations containing LSP. The results obtained were in good agreement with those obtained by use of high-performance liquid chromatography (HPLC), because the mean relative error, e_r, was <1.8%.     

The twisted skeleton of 1,9-diaminononane incatena-[catena-,μ-(1,9-diaminononane)cadmium(II) tetra-μ -cyanonickelate(II)]-o-xylene(2/1)

The Hofmann-danon-typeo-xylene clathrate Cd[NH₂(CH₂)₉NH₂]Ni(CN)₄·0.5(CH₃)₂C₆H₄, crystallizes in the triclinic space groupP witha = 15.118(3),b = 14.048(4),c = 7.325(1) Å, = 91.50(2), = 131.66(3), and = 107.50(2)°,V = 1051(1) ų andZ = 2. The structure, refined toR = 0.047 using 2851 reflections, reveals a three-dimensional host framework built of the layers of a two-dimensionalcatena-[cadmium tetra--cyanonickelate(Il)] network and of the ambidentate 1,9-diaminononane (danon) bridging the Cd atoms in adjacent networks. The guesto-xylene molecule is accommodated in the cavity formed in the interlayer space similar to that in the Hofmann-daotn-type. The skeleton of the danon in the Cd-NC₉N-Cd linkage takes a (gauche)₂(trans)₈ conformation twisted at the (gauche)₂ part in contrast with the all-trans conformation of 1,8-diaminononane in the Hofmann-daotn-type clathrate. The twisted (gauche)₂ part of the danon skeleton occupies the interlayer space to such an extent that void space available for the guest o-xylene molecule decreases to half that in the Hofmann-daotn-type clathrate Cd[NH₂(CH₂)₈NH₂]Ni(CN)₄·G.The Crystal structures of ,-Diaminoalkanecadmium(II)Tetracyanonickelate(II) - Aromatic Molecule Inclusion Compounds. VI.     

Synthesis,structure, and properties of organoplatinum(ii) derivatives of diphenyl ether

New mono- and disubstituted organoplatinum(II) derivatives of diphenyl ether,cis-(PhOC₆H₄-o)PtCl(PPh₃)₂ and (o-C₆H₄OC₆H₄-o)Pt(PPh₃)₂, were synthesized by the reaction of 2,2-dilithium diphenyl oxide withcis-Cl₂Pt(PPh₃)₂. Transmetallation of (PhOC₆H₄-o)AuPPh₃ withcis-Cl₂Pt(PPh₃)₂ was studied using³¹P NMR monitoring. This reaction proceeds with the retention of configuration to afford ClAuPPh₃ andcis-(PhOC₆H₄-o)PtCl(PPh₃)₂ under kinetically controlled conditions. The latter complex irreversibly isomerizes into thetrans isomer in the presence of equimolar quantities of ClAuPPh₃, whereas, in the presence of free PPh₃, this isomerization is reversible. The structures of the obtained diphenyl oxide derivatives of platinum were confirmed by³¹P NMR and FAB mass spectrometry. It was established by X-ray structural analysis that in thecis-(PhOC₆H₄-o)PtCl(PPh₃)₂ complex, the Pt atom is in a nearly square-planar coordination, and secondary intramolecular Pt...O interaction occurs.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 1814–1820, October, 1994.We would like to thank A. L. Blyumenfel'd and P. V. Petrovskii for recording the 31p NMR spectra, and D. V. Zagorevskii and K. V. Kazakov for measuring the mass spectrometric characteristics.This work was supported by the International Science Foundation (Project No. MDV 000).     

Schiff base complexes of dioxouranium(VI). VII. Dioxouranium(VI) acetate complexes with monobasic bidentate and bibasic tridentateSchiff bases

11 and 12 molar reactions of dioxouranium(VI) acetate dihydrate with the monobasic bidentateSchiff bases,o-HOC₆H₄CH=NR oro-HOC₁₀H₆CH=NR (R=C₂H₅,n-C₃H₇,n-C₄H₉ or C₆H₅) and bibasic tridentateSchiff bases,o-HOC₆H₄CH=NR(OH) oro-HOC₁₀H₆CH=NR(OH) (R=–CH₂CH(CH₃)- or —CH₂CH₂CH₂–) have been studied and derivates of the type UO₂(OAc)₂(SBH), UO₂(OAc)₂(SBH)₂, UO₂(OAc)₂(SBH ₂) and UO₂(OAc)₂(SBH ₂)₂ (whereSBH andSBH ₂ represent monobasic bidentate and bibasic tridentateSchiff base molecules respectively) have been isolated. These have been characterized by elemental analysis, conductance measurements and IR spectral studies.

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UO₂ ²⁺-Komplexe von Schiff-Basen. VII. Uranylacetat-Komplexe mit monobasischen zweizähnigen und bibasischen dreizähnigen Schiff-Basen

Zusammenfassung Es wurden in 1:1- und 1:2-molaren Reaktionen von UO₂(OAc)₂·2H₂O mitSchiff-Basen (L) Komplexe des Typs UO₂(OAc)₂ L bzw. UO₂(OAc)₂ L ₂ isoliert. Die Komplexe wurden mittels Elementaranalyse, Leitfähigkeitsmessungen und IR-Spektren untersucht.

     

Reactions of N-phenyl-o-semiquinonediimine complexes of nickel and platinum with carbonyl-containing low-valence iron and rhenium compounds

The reactions of o-semiquinonediimine complexes M[o-(NH)(NPh)C₆H₄]₂ (M = Ni (1) or Pt (2)) with carbonyl-containing iron and rhenium compounds were studied. The reactions of complexes 1 or 2 with Fe(CO)₅ afforded the Fe₂(CO)₆[-(NH)(NPh)C₆H₄] complex (3) containing the bridging N-phenyl-o-phenylenediamide ligand in high yield. The reaction of the Re(CO)₂(NO)Cl₂(thf) complex with complex 2 gave rise to the unusual mononuclear rhenium(iii) complex, viz., Re(Ph)[-¹-o-(NH)(NHPh)C₆H₄](CO)(NO)Cl₂ (4), no changes in the geometry of N-phenyl-o-phenylenediamine bound to the Re(NO)(CO)₂Cl₂ fragment being observed. The reaction of complex 2 with the Re(CO)₅Cl complex, which has been preliminarily treated with silver triflate, afforded the heterometallic complex (CO)Pt[-N,N-o-(N)(NPh)C₆H₄]₂ReCl[(NH)(NPh)C₆H₄]. The structures of the resulting complexes were established by X-ray diffraction analysis.     

Beiträge zur Chemie der Pyrrolpigmente, 40. Mitt.: Azafulvene,Schlüsselstellen beim Aufbau von Pyrrolpigmenten? —Eine neue Synthese von verdinoiden und rubinoiden Gallenfarbstoffen

Substituted azafulvenes were generated by dehydrogenation of 5-methyl-substituted pyrromethenones withDDQ and characterized by UV- and¹H-NMR-spectroscopy. Their electrophilic properties were demonstrated using several quenchers and furthermore they were used for a synthesis of verdinoid bile pigments (which easily can be converted to rubinoid systems by the action of NaBH₄) with nearly any desired unsymmetrical alkyl substitution patter: The azafulvene spezies was generated by the action ofDDQ on a 5-methylpyrromethenone and was quenched by an 5-unsubstituted pyrromethenone. The resulting rubinoid adduct was dehydrogenated immediatly byDDQ — yields were good to high.

39. Mitt.:Falk, H., Höllbacher, G., Hofer, O., Müller, N., Mh. Chem.112, 391 (1981).