New cyclopentadienylethylphosphane chelate complexes with unsymmetrical phosphane substitution

The syntheses, characterization, and some reactions of (phosphanylethyl) cyclopentadienyl chelate complexes of cobalt, rhodium, iridium, nickel, and chromium with unsymmetrical substitution at the phosphorus atom are described. The ligand systems were prepared by nucleophilic ring opening of spiro[2.4]hepta-4,6-diene with lithium tert-butylphenylphosphide or lithium tert-butylcyclohexylphosphide. The anionic ligands give the respective chelate complexes by treatment with metal halide reagents. In three cases it was possible to obtain X-ray crystal structure analyses. The cobalt chelate complex undergoes oxidative addition with a dihydrosilane, the reaction results in the formation of products with three stereogenic centers at phosphorus, cobalt, and silicon, which show dynamic behavior as indicated by VTNMR. The rhodium chelate complex undergoes oxidative addition of iodomethane with diastereoselective formation of the respective Rh(iii) chelate. While diastereoselectivity caused by a planar chiral indenyl ligand or by a stereogenic carbon center in the chelate backbone has earlier been observed, this is the first case of a stereoinduction by the stereogenic phosphorus ligand. Activation energies for the rotation of cobalt and rhodium chelates have also been determined by VTNMR. © 2011 The Royal Society of Chemistry and the Centre National de la Recherche Scientifique

New π-Extended 1,1′-Disubstituted Ferrocenes with Thioate and Dithioate End Groups

Extended π systems based on 1,1′-aryl or (2-arylethynyl) disubstitution at ferrocene with thioate or dithioate end groups are reported. In the context of molecular electronics, such end groups are possible alternative end groups for the attachment of molecular wires at gold surfaces. The respective thioates were successfully prepared in high yields via the respective carboxylic acid derivatives. Subsequent treatment with Lawesson's reagent led to the respective dithioates. However, this did not work in the presence of triple bonds, in these cases, product mixtures were formed. On the basis of literature evidence with Woollin's reagent, the selenium analog of Lawesson's reagent, one product was tentatively characterized as a double cyclization product of two triple bonds and two molecules of Lawesson's reagent. Preliminary experiments towards the formation of gold complexes by reaction with a Johnphos gold(I) salt are included

The First Anionic Thia-Fries Rearrangement at the Cobaltocenium Cation

While the chemistry of ferrocene is rich and widely explored, this is not the case for the isoelectronic cobaltocenium cation. Here we report the first syntheses of triflate substituted cobaltocenium cations based on respective (cyclopentadienone)(cylopentadienyl)cobalt(I) complexes, which have first been reported by Vollhardt et al. ca. forty years ago. Reaction with triflic anhydride affords the triflate substituted cobaltocenium cations, which upon treatment with lithium diisopropylamide undergo the first anionic thia-Fries rearrangements of cobaltocenium complexes. To our knowledge, this is, in addition, the first case of a deprotonation of a cobaltocenium complex by a lithium base. Alternatively, desilylation of silyl derivatives with cesium fluoride caused anion formation leading to the rearrangement products in higher yields. The 2-(trifluoromethylsulfonyl)(cyclopentadienone) complexes obtained were fully characterized including a crystal structure analysis. As with ferrocene, respective mesylates or tosylates do not undergo the rearrangement

Gardens of life: Multifunctional and ecosystem services of urban cemeteries in Central Europe and beyond—Historical, structural, planning, nature and heritage conservation aspects

Cemeteries are often seen as monofunctional spaces for burial and mourning and, within the dynamically changing urban fabric, as a planning conundrum. Long periods of stability have also turned these untouched and hidden places into refugia for nature and wildlife. In booming and dense cities with high land use pressures and housing shortages, in particular, as the amount of burial ground needed per citizen decreases and burial cultures change, the cemetery has become a contested nature, as a simultaneous space of emotion, commerce and community. We revisited the diversity and ontogenesis of cemeteries, and the interactions with neighboring uses of the urban matrix. Our review demonstrates a wide range of different ecosystem services of urban cemeteries, beyond potential as hotspots of culture and biodiversity. We highlight their multifunctional character and the need for a holistic and trans-disciplinary evaluation using multistakeholder approaches to further develop cemeteries as a crucial element of sustainable urban landscapes.Peer Reviewe

High yield synthesis and structures of some achiral and chiral (diphosphine)tetracarbonylchromium(0) chelate complexes with tetracarbonyl(norbornadiene)chromium(0) as complexation reagent

Tetracarbonyl(norbornadiene)chromium(0) was used as complexation reagent in the synthesis of tetracarbonylchromium chelate complexes of dppe, dppb, dppf, DIOP, BINAP, and Tol-BINAP. In all cases the reactions took place under mild reaction conditions with excellent, almost quantitative yields. X-ray crystal structure analyses of the dppf and BINAP tetracarbonylchromium(0) complexes are presented.DF

Die 'Soldatenmütter von St. Petersburg': 'Schützen wir unsere Söhne'

'Die vorliegende Arbeit basiert auf Erkundungen während vier Aufenthalten (1996-2000) bei der Bürgerrechtsorganisation 'Soldatenmütter von St. Petersburg'. Erstmals wird der Versuch unternommen, die Tätigkeit russischer Soldatenmütter genauer zu schildern und zu analysieren. Zu diesem Zweck wurden Übungen in der 'Schule der Menschenrechte 'Schützen wir unser Söhne'' der Petersburger Bürgerrechtsorganisation mit den nachfolgenden Einzelberatungen mehrfach aufgezeichnet. Außerdem wurden zahllose Interviews mit ratsuchenden Müttern und Großmüttern (selten mit Vätern) geführt. In den Jahren 1998-2000 hat die Zahl der Wehrpflichtigen und Wehrdienstleistenden, die sich selbst an die Soldatenmütter wenden, merklich zugenommen. Mit wenigen Ausnahmen waren die Interviewpartner/-innen ausgesprochen auskunftsfreudig. Deutlich zurückhaltend antworteten nur Offiziere der Petersburger Garnison, die gelegentlich bei den Soldatenmüttern anzutreffen sind. Auch Ella M. Poljakova und Elena Ju. Vilenskaja, die beiden Vorsitzenden der Bürgerrechtsorganisation, wurden umfassend befragt. Ferner wurden die Publikationen und das Pressearchiv der Soldatenmütter herangezogen. Die Abschriften der Kassetten (Aufnahmen: 17.1.-5.2.2000) liegen dem BIOst vor. Die in der Arbeit vorkommenden Zitate entstammen diesen Aufzeichnungen.' (Textauszug)'The present report is based on exploratory studies carried out by the author during four periods between 1996 and 2000 spent with the civil rights organisation 'Soldiers' Mothers of St. Petersburg'. It is the first-ever attempt to describe and analyse the activities of Russian soldiers' mothers more closely. For this purpose, the author recorded several exercises and the following individual consultation sessions in the 'School of Human Rights 'Let us protect our sons'' run by the St. Petersburg civil rights organisation. She also conducted numerous interviews with mothers and grandmothers (and just a few fathers) in need of counselling. In the years 1998-2000, the number of young men liable to military service, and even of serving conscripts, who are themselves turning to the Soldiers' Mothers for advice has increased significantly. With just a few exceptions, the persons interviewed were very keen to voice their views. Clearly hesitant responses came only from officers of the St. Petersburg garrison, who are occasionally to be found visiting the Soldiers' Mothers. Ella M. Polyakova and Elena Yu. Vilenskaya, the two Chairwomen of the civil rights organisation, were also extensively questioned. The author also had access to the publications and to the press archive of the Soldiers' Mothers. The transcriptions of the tape recordings (recorded 17.1. - 5.2.2000) are in the possession of the Federal Institute. The quotes cited in this report are taken from these recordings.' (extract

Validation of the NEMO-ERSEM operational ecosystem model for the North West European Continental Shelf

This paper details updates to the Met Office's operational coupled hydrodynamic-ecosystem model from the 7 km Medium-Resolution Continental Shelf – POLCOMS-ERSEM (MRCS-PE) system (Siddorn et al., 2007) to the 7 km Atlantic Margin Model NEMO-ERSEM (AMM7-NE) system. We also provide a validation of the ecosystem component of the new operational system. Comparisons have been made between the model variables and available in situ, satellite and climatological data. The AMM7-NE system has also been benchmarked against the MRCS-PE system. The transition to the new AMM7-NE system was successful and it has been running operationally since March 2012 and has been providing products through MyOcean (<a href="http://www.myocean.eu.org" target="_blank">http://www.myocean.eu.org</a>) since that time. The results presented herein show the AMM7-NE system performs better than the MRCS-PE system with the most improvement in the model nutrient fields. The problem of nutrient accumulation in the MRCS-PE system appears to be solved in the new AMM7-NE system with nutrient fields improved throughout the domain as discussed in Sect. 4. Improvements in model chlorophyll are also seen but are more modest

Anionic Thia-Fries Rearrangement at Ferrocene: A Computational and Experimental Study

Ferrocenyl triflate (1) and 1,1′-ferrocenediyl ditriflate (5) undergo single and double anionic thia-Fries rearrangements at low temperatures in high yields with the latter forming exclusively the respective meso product. The detailed mechanisms of the anionic thia-Fries rearrangement of 1, as well as that of the double anionic thia-Fries rearrangement of 5, are examined with the aid of DFT calculations. Functionals, basis set and pseudopotentials applied were selected in accordance with a benchmark using the crystal structure analysis of the prime product 3 of the reaction of 1 before hydrolysis for comparison, which has so far not been reported. The unprecedented meso diastereoselectivity of the double anionic thia-Fries rearrangement of 5 is shown to be a result of a distinctive degree of chelation arising from two diastereomeric transition states

Fluorosulfonylferrocene, (Trifluoromethylsulfonyl)ferrocene and New Ferrocenyl Sulfonates: Directed ortho Lithiation and New Anionic Thia-Fries Rearrangements at Ferrocene

Ferrocenyl triflates are known to undergo anionic thia-Fries rearrangements at low temperature in high yields. In order to expand the scope of this reaction, ferrocenyl sulfonates and sulfonylferrocenes were prepared and their reactivity investigated. Treatment of ferrocenyl fluorosulfonate with lithium 2,2,6,6-tetramethylpiperidide gave rise to a new anionic thia-Fries rearrangement at ferrocene. The formation of a rare oxathiine was observed with ferrocenyl (pentafluorophenyl)sulfonate as a result of an ortho lithiation and a subsequent intramolecular nucleophilic aromatic substitution. In contrast to fluorinated ferrocenyl sulfonates, fluorosulfonylferrocene as well as (trifluoromethylsulfonyl)ferrocene underwent ortho lithiation under comparable reaction conditions

Bidirectional Synthesis, Photophysical and Electrochemical Characterization of Polycyclic Quinones Using Benzocyclobutenes and Benzodicyclobutenes as Precursors

Quinones have widespread applications in view of their interesting chemical and photophysical features. On the other hand, benzocyclobutenes (BCBs) are generally masked reactive dienes suitable for the [4+2] cycloaddition reactions. Here, benzocyclobutenes and benzodicyclobutenes (BDCBs) were prepared and further reacted with benzoquinone and naphthoquinone in order to obtain some new polycyclic quinones with highly extended π systems, namely, 6-bromo-5,8-dimethoxyanthracene-1,4-dione, 2,9-dibromo-1,4,8,11-tetramethoxypentacene-6,13-dione, 9-bromo-7,10-dimethoxytetracene-5,12-dione, 3,10-dimethoxycyclobuta[b]anthracene-1,5,8(2H)-trione, 6,10,17,21-tetramethoxynonacene-1,4,8,12,15,19-hexaone, and 3,12-dimethoxycyclobuta[b]tetracene-1,5,10(2H)-trione. In addition to their spectroscopic characterization the new compounds are investigated by UV and fluorescence spectroscopy, cyclic voltammetry, and DFT calculations