Band 61, Heft 11

Deprotonation of 6-methyl-6-dimethylaminofulvene with a lithium amide base gave lithium (1-dimethylamino-ethenyl)cyclopentadienide. In the crystal it features a close to perfect oligomeric supersandwich structure. In contrast to related (aminomethyl-Cp)Li complexes here the enamino substituent is not directly involved in the formation of the oligomeric suprastructure.

The preparation, spectroscopic properties and crystal structure of a tetranuclear copper(II) resorcin[4]arene-based complex with the cap-bpa ligand [cap = resorcin[4]arene-based cavitand, bpa = bis(pyridyl)methylamine] are reported. The orientation of each (bpa)Cu fragment in the complex is perpendicular to the cap bowl. All four copper centers are only coordinated to the tridentate bpa moiety.

DFT-calculations (RB3LYP/LANL2DZp) show that the migration of a proton inside [1.1.1]- and [2.2.2]-cryptand from one nitrogen atom to the other follows different paths. While the proton in [H⊂1.1.1]-cryptand moves via an ether oxygen atom (activation energy: 19.2 kcal/mol), the proton in [H⊂2.2.2]-cryptand moves directly from one nitrogenatom to the other (activation energy: 16.1 kcal/mol). Our calculations rule out the application of doubly protonated [2.2.2]-cryptands as anion hosts.

Novel macrocyclic dipicolinic acid acylated peptides based on upper rim bridged peptidocalix[ 4]arenes, peptido-pyridines or hybrid structures of both, were synthesized as potential molecular metallacages and chemosensors. While conventional azide or mixed anhydride (ethyl chloroformate) peptide couplings served well for assembling the L-tyrosine or L-ornithine peptide backbones, the acid chloride of pyridine-2,6-dicarboxylic acid (dipicolinic acid) acid served as the complementary acylating agent. The structure assignment of the new compounds was based on chemical and spectroscopic evidences. Some of these compounds exhibit antimicrobial activities.

Kinetics of oxidation of L-cysteine by pairs of trans and racemic cis isomers of cobalt(III) and iron(III) based transition metal complexes have been studied in aqueous solution. Kinetics measurements were run under pseudo first order conditions in which the concentration of cysteine is between one and two orders of magnitude greater than that of the isomers of the transition metal complex. The orders of the reaction with respect to both cysteine and the isomer were determined. The observed rate constants and the overall rate constants of the oxidation process were measured. For all geometrical isomers, it was found that the rate constant of oxidation of L-cysteine by the trans isomer is between one to three orders of magnitude greater than that by the cis isomer. The difference in rates can be explained by a geometric factor around the metal ion center in the complex. The less crowded isomer (trans) makes electron transfer easier and hence facilitates the oxidation process which leads to a higher oxidation rate.

In an unusual ring enlargement reaction the heterocyclic ligand in a pentacarbonyl(pyrazolidene) chromium complex is transformed in high yield into the corresponding tetrahydropyrimidinylidene ligands by a deprotonation/protonation (or deprotonation/alkylation) sequence.

Copper(II)bis{2-[(4-iodophenyl)iminomethyl]-6-methoxy-phenolate} has been synthesized, characterized by UV-visible spectroscopy, and its crystal structure determined by X-ray diffraction. The Cu atom is situated on a twofold axis and the geometry around the metal centre can be described as distorted square planar with a trans configuration. The absorption maxima are shorter than 450 nm, giving rise to good optical transparency in the visible and near IR. To reveal the microscopic thirdorder NLO properties, the static second hyperpolarizabilities have been evaluated by using the ab initio time-dependent Hartree-Fock (TDHF) method. According to the results, the title complex exhibits non-zero γ values, implying microscopic third-order NLO behavior.

The additions of methanol to the dichloropalladium(II) complex with C-(2-pyridyl)-Nmethylnitrone led to the formation of the Pd(II)-coordinated α-methoxy-α-(2-pyridyl)-N,Ndimethylhydroxylamine. It has been demonstrated that the Pd(II) complexation is essential for the stabilization of α-alkoxyhydroxylamines.

The complexes CpCo(CO) 2 (Cp = C 5 H 5 , C 5 H 4 Me, C 5 Me 5 and C 5 Ph 5 ) (1a - d) react with thiirane C 2 H 4 S under UV-irridiation in THF to form the dinuclear μ2-1,2-ethanedithiolate-S,S complexes [(CpCo) 2 (μ 2 -S 2 C 2 H 4 )] (2a - d) as main products. Using column chromatography, in case of Cp = C 5 H 5 Me also the dimeric complex [C 5 H 4 MeCo(μ 2 -S 2 C 2 H 4 )]2 (3b), in case of Cp = C 5 Ph 5 the mixed disulfido-sulfido complex [(C 5 Ph 5 Co) 2 (μ 2 -S 2 )(μ 2 -S)] (4d) were isolated in small yields. Only 2a reversibly adds SO 2 gas to form the μ 2 -SO 2 complex [(C 5 H 5 CoSCH 2 )2(μ 2 -SO 2 )] (5a). A bromo ligand bridging the Co atoms can be introduced by the reaction of [(C 5 Me 5 CoBr 2 )] 2 (6c) with 1,2-ethanedithiol which gives the cationic complex [(C 5 Me 5 CoSCH 2 ) 2 (μ 2 -Br)] 2 CoBr4 (7c). All compounds have been characterized by their IR, 1 H and 13 C NMR and MS spectra and compounds 2b - d, 3b and 7c by X-ray structure analyses, which prove the pseudo tetrahedral skeleton (CpCoS) 2 and the ethane bridge between both sulfur atoms. 3b shows, however, a new unsymmetrical bonding mode of both dithiolato bridges with η 1 -S und μ 2 -S ligand functions.

Two new charge transfer salts based on Keggin polyoxoanions, [Hen] 2 [H 2 en][PMo VI 11 Mo V O 40 ]・3.5H2O (1) and [Hpy] 4 [GeMo VI 12 O 40 ]・2H 2 O (2) (en = ethylenediamine, py = pyridine), have been synthesized and characterized by single crystal X-ray diffraction, elemental analyses, IR spectra, UV/vis spectra, cyclic voltammograms and X-ray photoelectron spectra. The IR spectra and solid reflectance electronic spectra of the title compounds indicate that interactions exist between the polyanions and the organic substrates, which are probably caused by charge transfer.

Crystals of [Ca(NTC)(H 2 O) 2 ]·H 2 O (1) (NTC = naphthalene-1,4,5,8-tetracarboxylate-1,8-monoanhydride) and [Sr 2 (NTC) 2 (H 2 O) 8 ]·H 2 O (3) were obtained by layering an aqueous solution of sodium naphthalene-1,4,5,8-tetracarboxylate with an aqueous solution of CaCl 2 or SrCl 2 , respectively. Crystals of [Sr(NTC)(H 2 O) 2 ]· 2 H 2 O (2) and [Ba(NTC)(H 2 O) 2 ] (4) were obtained by gel crystallisation. The NTC in 1 and 2 is tridentate, and in 4 pentadentate, forming bonds to the cations using the oxygen atoms of the carboxylate and one oxygen atom of anhydride groups. In 3 the cations are associated only via the oxygen atoms of carboxylate groups. 1 and 2 have layer structures, 3 has a chain structure, and 4 forms a three-dimensional coordination network. The number of O atoms around the cations is eight for 1, 2 and 4, and nine for 3.

Three structures of the form bis(imidazolidine-2-thione)gold(I) disulfonylamide [disulfonylamide = benzene-1,2-di(sulfonyl)amide (1), di(4-chlorobenzenesulfonyl)amide (2), di(4-iodobenzenesulfonyl) amide (3)] were determined. Compound 3 crystallizes with four independent formula units. The cations in 1 and 3 show an antiperiplanar conformation about the S···S axis, whereas the corresponding torsion angle in 2 is 72°. The packing in 1 consists of linked ribbons in which the NH groups of neighbouring cations are bridged by O-S-O groups of the anions. Compound 2 exhibits a complex layer structure in which several multi-centre hydrogen bonds are observed. The structural subunits of compound 3 involve an alternating anion-cation chain for two of the cations and inversionsymmetric anion-cation dimers for the other two cations. Short C-H···Au contacts (shortest H···Au 2.63 Å in 2) contribute to the packing of compounds 2 and 3.

Isobutylammonium selenite and its sesquihydrate were obtained in low yields by reaction of selenium dioxide with the neat amine in the presence of small amounts of water. Both structures were determined by X-ray methods and proved to contain two independent formula units. In both cases, layer structures [(CH 3 ) 2 CHCH 2 NH 3 ] 2 [SeO 3 ] are formed in which all NH hydrogen atoms act as single hydrogen bond donors, and all selenite oxygen atoms accept two hydrogen bonds. The layers contain six independent rings; the anhydrous substance has all rings of graph set R 3 4 (10), whereas the sesquihydrate has two each of R 4 4 (12), R 2 4 (8) and R 3 4 (10). The three independent water molecules of the sesquihydrate attach themselves to the layer structure by further classical hydrogen bonds to the selenite oxygen atoms.

The reaction of allylchlorosilanes (AllSiCl 3 , AllSiPhCl 2 ) with the tetradentate salen-like ligand 1, o-HO-p-MeO-C 6 H 3 -C(Ph)=N-(CH 2 ) 2 -N=C(Ph)-C 6 H 3 -p-OMe-o-OH, yields pentacoordinate silicon complexes of an allyl-substituted ligand system (o-O-p-MeO-C 6 H 3 -C(Ph)=N-(CH 2 ) 2 - N-C(Ph,All)-C 6 H 3 -p-OMe-o-O)SiR (2a: R = Ph, 3: R = Cl). The allyl shift step involved in the formation of 2a and 3 probably occurs via an intermediate hexacoordinate silicon complex. This reaction is diastereoselective. The missing diastereomer of 2 (2b) was prepared using an alternative synthesis route, which starts from the trimethylsilyl derivative of ligand 1 o-Me 3 SiO-p-MeO-C 6 H 3 -C(Ph)=N- (CH 2 ) 2 -N=C(Ph)-C 6 H 3 -p-OMe-o-OSiMe 3 . The diastereomers of 2 obtained from modified reaction pathways give rise to suggestions about the mechanism of formation of these complexes. Further functionalization of the allyl-substituted ligand system of 3 was carried out by hydrosilylation with HSiCl3 to yield complex 4 (o-O-p-MeO-C 6 H 3 -C(Ph)=N-(CH 2 ) 2 -N-C(Ph)[(CH 2 ) 3 -SiCl 3 ]- C 6 H 3 -p-OMe-o-O)SiCl.

The very reactive α-oxo-thioketone derivatives 2a - d, generated via thermolysis of spirobenzopyran- 3’,2-[1,3,4]oxadithiino[5,6-c]benzopyran-4’-ones 1a - d, reacted with 2,3-dimethyl-1,3-butadiene and 1,3-cyclohexadiene under [4+2]-cycloaddition to afford spirobenzopyran-3’,6-thiapyran-4’-one adducts 3a - d and spirobenzopyran-3’,3-thiabicyclo[2.2.2]oct-5-en-4’-one adducts 4a - d, respectively. On the other hand, the reaction of α-oxo-thioketones 2a - d with isoprene afforded regioselectively only 3-methyl-thiapyran derivatives 5a - d. Single crystal X-ray diffraction studies of 4b, 4c, and 5a give a good support for the established structure.

Reaction of 4-amino-6-methyl-3-thio-3,4-dihydro-1,2,4-triazin-5(2H)-one (1) with 2-methoxybenzaldehyde, 4-methoxybenzaldehyde, 2-pyridinecarbaldehyde, and 2,4-dichlorobenzaldehyde under classical heating and microwave irradiation in a solventfree system led to the corresponding imines (Schiff bases) 2-5. All synthesized compounds have been characterized by IR and NMR spectroscopy, mass spectrometry and by X-ray diffraction studies.

Copolymerizations of ethylene and 1,7-octadiene were carried out employing homogeneous catalysts Cp 2 ZrCl 2 , Ph 2 C(Flu,Cp)ZrCl 2 and Et(Ind)2ZrCl2, and methylaluminoxane as cocatalyst. The polymerization characteristics, such as catalytic activity, polymerization rate, copolymer composition, and thermal properties were examined in relation to the catalyst type. Different comonomer concentrations were employed, and the reaction time was varied, ranging from 1 h up to 4 h, at 90°C and at 0.5 bar ethylene pressure. The results showed that the catalyst Cp 2 ZrCl 2 was more efficient than Et(Ind) 2 ZrCl 2 in the preparation of high diene content ethylene/1,7-octadiene copolymers. On the other hand, Et(Ind) 2 ZrCl 2 and Ph2C(Flu,Cp) 2 ZrCl 2 catalysts produced low insaturation content but possibly formed cyclic structures and crosslinking.

Fractionation of the methanol extract of Phlomis amanica resulted in the isolation of a new pimarane type diterpene, amanicadol (1), together with the known glycosides lamiide, verbascoside (= acteoside), syringaresinol-4-O-β -glucoside, liriodendrin, syringin, and a caffeic acid ester, chlorogenic acid. The structure of the new compound was established on the basis of extensive 1D and 2D NMR spectroscopic data interpretation. Molecular modeling studies on 1 were conducted and showed that it exhibited low conformational flexibility. Additionally, NMR chemical shifts were calculated for 1 in vacuo, and calculated values were in very close agreement with those found experimentally.

The aerial parts of Amphoricarpos neumayeri ssp. murbeckii afforded eleven guaianolides with the same relative (1αH,4β H,5αH,7αH) configuration of the basic skeleton. All of them contained a CH 2 OX (X = H, acetyl or isovaleroyl) group in 4α-position, typical for amphoricarpolides. Four compounds (1 - 4) were isolated before from the same species, originating from different localities. Guaianolides 5 - 11 are new compounds. Compounds 7 and 8 were epoxidized at the 10α(14)-position. Instead of the Δ 11(13) -double bond, observed in all previously isolated guaianolides from the same species, the four lactones contained 11α,13-diol (8 - 10) or 11α-OH,13-chloro (11) moieties respectively.

Two new β -carboline alkaloids, epi-strictosidinic acid (1) and strictosidinic ketone (2), together with two known alkaloids, calycanthine (3) and strictosidinic acid (4) besides the triterpene ursolic acid (5) were isolated from the roots and leaves of Palicourea coriacea. The structures of the isolates were elucidated on the basis of spectral data, particularly COSY, HMQC and HMBC experiments, and HR mass spectra.

A mixture of four new butyrospermol and two known β -sitosterol fatty acid esters, was obtained from the fruit of a Chinese mangrove Xylocarpus granatum. The structures of these compounds were established on the basis of spectroscopic data and chemical means. The butyrospermol fatty acid esters were characterized as mainly comprising butyrospermol 3β -O-palmitate (1), butyrospermol 3β -O-oleate (2), butyrospermol 3β -O-stearate (3) and butyrospermol 3β -O-linoleate (4). The β - sitosterol fatty acid esters were identified as mainly containing β -sitosterol 3β -O-myristate and β - sitosterol 3β -O-oleate.

Two new anthraquinones were isolated from the marine Streptomyces sp. B8000, in addition to the known metabolites 3,8-dihydroxy-1-propylanthraquinone-2-carboxylic acid (1a), indole-3- carboxylic acid, 2-desoxythymidin, indole-3-acetic acid methyl ester, N-acetyltyramine, and nicotinic acid. The structures of the new compounds were established as 8-hydroxy-3-methoxy-1- propylanthraquinone (2a) and 3,8-dihydroxy-1-propylanthraquinone (2c) on the basis of extensive spectroscopic analyses. Some derivatives were prepared and their biological activities were studied.