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The insecticide DDT is an omnipresent environmental contaminant and an ongoing toxicological concern. The recent discovery that methylenetetrahydrofolate (MTHF) models are capable of reducing a range of halocarbons to hydrocarbons under biomimetic conditions has prompted us to investigate the possible role of MTHF in the metabolism of DDT. We now report that the reaction of MTHF models with DDT produces no less than five known in vivo metabolites of DDT, namely DDD, DDE, DDMU, DBP, and DDM. The capability of the MTHF models to produce the full spectrum of known DDT dehalogenation products is strong evidence that the mechanistically obscure metabolism of DDT may involve MTHF. The findings also suggest that DDT should be capable of disrupting folate-dependent pathways.

Methylenetetrahydrofolate models (green substructure) reduce organohalides to the respective hydrocarbons under biomimetic conditions and mimic the activity of dehalohydrogenases., Halocarbons R–X are reduced to hydrocarbons R–H by folate model compounds under biomimetic conditions. The reactions correspond to a halide–hydride exchange with the methylenetetrahydrofolate (MTHF) models acting as hydride donors. The MTHF models are also functional equivalents of dehalohydrogenases but, unlike these enzymes, do not require a metal cofactor. The reactions suggest that halocarbons have the potential to act as endocrinological disruptors of biochemical pathways involving MTHF. As a case in point, we observe the rapid reaction of the MTHF models with the inhalation anaesthetic halothane. The ready synthetic accessibility of the MTHF models as well as their dehalogenation activity in the presence of air and moisture allow for the remediation of toxic, halogenated hydrocarbons.

The reduction of halocarbons by NADH models and NADH under ambient conditions is reported as a new type of reactivity pointing towards a hitherto unknown disruptive pathway for NADH/NADPH-dependent processes. The reaction was studied with the omnipresent pesticide DDT, the inhalation anesthetic halothane, and several simple halocarbons. The halide–hydride exchange represents a biochemical equivalent for the reduction of halocarbons by traditional synthetic reagents like silanes (R3Si–H) and stannanes (R3Sn–H). High precision thermochemical calculations (CBS-QB3) reveal the carbon–hydrogen bond dissociation energy of NADH (70.8 kcal·mol−1) to be lower than that of stannane (SnH4: 78.1 kcal·mol−1), approaching that of the elusive plumbane (PbH4: 68.9 kcal·mol−1). The ready synthetic accessibility of NADH models, their low carbon–hydrogen bond dissociation energy, and their dehalogenation activity in the presence of air and moisture recommend these compounds as substitutes for the air-sensitive or toxic metal hydrides currently employed in synthesis.

SummaryIn clinical practice sclerotherapy of intradermal varicose veins seems to be more effective in elderly patients. Patients, methods: After prior duplex-sonographic investigation 48 patients with intradermal varicose veins (diameter 1–2 mm, C1,EP, AS, PR) were included. 24 patients (group 1) received Polidocanol (0.25% Aethoxysklerol®) injection sclerotherapy and 24 patients (group 2) received sodium chloride injections. In all subjects an area of 100 square centimetres of the lower limb was treated. The borders of each area were marked and photo documented. The injections were performed by an examiner who was unaware of which liquid had been injected. Compression therapy was performed for one week after the treatment. One and four weeks later the results were controlled by the physician who performed the injections and documented by an independent photographer. The glossy prints of the areas before and four weeks after the treatment were sent to two blinded independent external reviewers. The reviewers noted their evaluation on a visual analogue scale (VAS). The reviewers received each anonymous photodocument twice within 3 weeks. Results: The VAS of both experts showed a significant difference between the results in group 1 and group 2 (p < 0.0001). Median of efficacy was 58.5% in group 1 (verum) and 0.5% in group 2 (placebo). Both experts had a stable intraindividual reliability of 85% and further both raters didn´t differ concerning their ratings. In group 1 (verum) the Pearson correlation coefficient showed a significant correlation between the therapeutic outcome and the age of the treated patients. Conclusions: Injection sclerotherapy of intradermal varicose veins using 0.25 %Polidocanol (Aethoxysklerol) is an efficient treatment that leads to a good aesthetic outcome. In elderly patients sclerotherapy is more efficient.

Analyse des Kontraktionsverhaltens und des intrazellularen Kalziumstoffwechsels im isolierten atrialen Myokard des Menschen. Isoliertes menschliches atriales Myokard aus chirurgischem Resektionsmaterial wurde mit Fura 2 zur Messung des intrazellularen Kalziums untersucht. Die Praparate wurden supramaximal elektrisch stimuliert. Kraftentwicklung und intrazellulares Kalzium wurden bei ansteigenden Ivabradin-Konzentrationen simultan gemessen. Unterschiedliche Stimulationsfrequenzen wurden verwendet, um die Kraft-Frequenz-Beziehung unter Ivabradin-Einfluss zu analysieren. Mit steigender Ivabradin-Konzentration kam es zu einem signifikanten Anstieg der Amplituden des intrazelluaren Kalziumtransienten und der Kraftamplituden (p

Die infektiose Endokarditis wird primar konservativ behandelt. Bei Persistenz der Infektion und zunehmender hamodynamischer Symptomatik sollte erregerabhangig und im Einklang mit der aktuellen Leitlinie unverzuglich die chirurgische Therapie erfolgen, ohne die Beherrschung der lokalen bzw. systemischen Infektion abzuwarten. Verbesserte chirurgische Ergebnisse lassen die folgenden Empfehlungen zur Terminierung der Operation gerechtfertigt scheinen: Wesentlichster Prognosefaktor der chirurgischen Therapie der akuten, floriden Endokarditis ist die „verschleppte Operationsindikation“. Die Ausbildung lokaler intramyokardialer Abszesse oder einer septischen Kardiomyopathie (zusatzlich zur vitienbedingten akuten Einschrankung der Pump- und Muskelfunktion), das konsumierende systemische septische Krankheitsbild und die zunehmende Auspragung von z.T. irreversiblen Organschadigungen (Leber, Milz, Niere, Gehirn, Lunge, Knochen etc.) konnen bei verschleppter Indikation auch nach chirurgischer Sanierung aller lokalen Herde fur den Therapieverlauf bestimmend bleiben. Bei gesicherten ausgepragten Vegetationen im linken System ist auch der Nachweis eines akuten zerebralen Ereignisses keine Kontraindikation fur eine sofortige chirurgische Intervention. Die verschleppte Indikation kann zu chirurgisch nicht mehr adaquat sanierbaren Lokalbefunden fuhren, so dass die Prognose dieser Patienten infaust werden kann. Im eigenen Krankengut wurde praoperativ gefunden: NYHA (New York Heart Association) III–IV > 50%; Nierenversagen > 15%, systemische Embolien > 30%, Schlaganfalle > 8%, kardiogener Schock > 10%. Infiziertes Gewebe muss radikal exstirpiert werden, selbst unter Inkaufnahme groserer Gewebsdefekte, die chirurgisch zu sanieren sind. Eine Verletzung des Reizleitungssystems wird im Interesse einer vollstandigen Infektsanierung in Kauf genommen. Bei radikaler chirurgischer Therapie sind Klappenprothesen in Aorten- und Mitralklappenposition selbst bei Vorliegen von paravalvularen Abszessen und Staphylokokkeninfektionen anderen Verfahren gegenuber zumindest gleichwertig. Nicht die Art der implantierten Prothese, sondern die Kompromisslosigkeit der chirurgischen Technik ist die entscheidende prognostische Grose. Bei Endokarditis in Trikuspidalklappenposition ist eine plastische Korrektur fast immer, in Mitralklappenposition oft moglich. Ein aggressives chirurgisches Therapiekonzept schliest die chirurgische Sanierung extrakardialer Herde im unmittelbaren zeitlichen Zusammenhang mit der Herzoperation ein. Der postoperative Verlauf wird bei adaquater chirurgischer Therapie weniger vom infektiosen Lokalbefund im Herzen als vielmehr von den Folgen der praoperativ bestehenden Systemerkrankung mit ggf. persistierenden sekundaren Organmanifestationen bestimmt. Da die Ergebnisse der konservativen Therapie der Endokarditis in einigen Subgruppen nach wie vor unbefriedigend sind, wird die verbesserte (auf Radikalitat und Aggressivitat des Debridements fusende) chirurgische Therapie auch zeitnah bei einigen Patienten in Betracht kommen, die bisher primar fur die konservative Therapie vorgesehen waren.

Experimental values for the strength of the sulfur–sulfur bond scatter over a wide range and are frequently in disagreement with each other. For S8, reliable experimental data seem to lack entirely. To check experimental data and establish the strength of the sulfur–sulfur bond in S8, high-precision thermochemical calculations (G3, CBS-Q) and DFT methods were employed. The calculations confirm a stunning range for the strength of the sulfur–sulfur bond with energies between 77.7 kcal for FSSF and only 41.8 kcal for tetrasulfane, HSS–SSH. For the pivotal bond energy of elemental sulfur, S8, the bond energy is 40.5 kcal but can be narrowed to 38.0–39.2 kcal mol–1 by including CBS-QB3 data. While older DFT methods are not well suited to accurately reproduce the S–S bond energies, excellent data can be obtained with the recently introduced Boese–Martin (BMK) hybrid DFT method. Atoms in molecules (AIM) calculations reveal significant multiple bonding and spin delocalization in the sulfur radicals XS·. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)

Fragestellung Die Hypothese wurde gepruft, ob sich auf der Grundlage der Analyse isolierten menschlichen Myokards eine geschlechtsspezifische Beziehung zwischen Kontraktionsverhalten und Ubergewicht nachweisen liese.

Durch akute mechanische Alterationen (Muskeldehnung bzw. -verkurzung) konnen atriale Rhythmusstorungen induziert werden. Die vorliegende, unter exakt kontrollierten experimentellen Bedingungen durchgefuhrte Analyse leistet einen Beitrag, mogliche Ursachen hierfur aufzuklaren. Isolierte menschliche atriale Trabekel (0,3 x 5,0 mm) wurden Patienten vom rechten Herzohr entnommen, die sich einer koronaren Bypassoperation unterzogen (n = 17). Nach Ladung mit dem Fluoreszenzfarbstoff FURA-2 zur Kalziumbestimmung (Messbedingungen: optimale Lange, isometrische Bedingungen, oxygenierte Krebs-Henseleit-Losung, 37° C, supramaximale Stimulation mit 0,5 Hz) und einer Aquilibrierungsperiode wurden bei den Praparaten rasche Entdehnungsprozeduren bis hin zur “slack-length” (A), auf 90 % (B) bzw. auf 95 % der optimalen Lange (Lmax) (C) durchgefuhrt. Systolische und diastolische Kraftentwicklung sowie systolisches und diastolisches Kalzium wurden simultan uber 2 min nach Auslosung der experimentellen Prozeduren registriert. Die rasche ”unloading procedure” war assoziiert mit Extrakontraktionen bei 13 von 17 Muskelpraparaten bei Muskellangenreduktion auf slack length (A), bei 8 von 17 Praparaten bei Entdehnung auf 90 % Lmax (B) und bei 2 von 17 Praparaten bei Entdehnung auf 95 % Lmax (C). Uberraschenderweise zeigte die Form des intrazellularen Kalziumtransienten in einigen Praparaten substanzielle Veranderungen mit einem biphasischen Kalziumtransienten bei monophasischer Kraftantwort, was wiederum auf wenigstens zwei Populationen von Muskelfasern im selben multizellularen Praparat hinweist. Dieses Phanomen wurde dokumentiert bei 8 von 17 in (A), 4 von 17 in (B) und 1 von 17 in (C). Die Befunde zeigen erstmals die Prasenz von mindestens zwei Muskelfaserpopulationen im multizellularen Muskelpraparat, die unterschiedliche Arten der elektromechanischen Kopplung aufweisen. Damit ist nach unserer Einschatzung ein Ausgangspunkt moglicher atrialer Rhythmusstorungen unter experimentellen Bedingungen nachgewiesen worden. Der Entdeckung mechanisch induzierter biphasischer Kalziumtransienten (mit monophasischer Kraftantwort) kommt moglicherweise entscheidende Bedeutung fur das Verstandnis der Entstehung atrialer Rhythmusstorungen zu.

The steric and electronic influence of N-alkyl substituents on the dimerization energies ΔG° of Wanzlick carbenes (imidazolidin-2-ylidenes) was investigated experimentally and through DFT methods for a series of non-symmetrically substituted Wanzlick carbenes. A series of 3-alkyl-1-tert-butylimidazolidin-2-ylidenes with decreasing steric demand of the alkyl substituent (isopropyl, ethyl and methyl) were obtained in four steps from the commercially available N-alkylaminoethanol compounds. The carbenes are hydrolytically sensitive, colorless oils that can be distilled without decomposition and show no sign of dimerization to the respective enetetramines, even after prolonged heating. Calculations at the B98/6-31G(d) level confirm that the dimerization of all three carbenes is thermodynamically unfavorable. To separate the steric and electronic stabilization of Wanzlick carbenes by N-alkyl substituents, the formation energies of R,H3 mono-alkyl enetetramines were used to derive electronic increments for the N-alkyl substituents. The computational data show that all alkyl substituents electronically stabilize Wanzlick carbenes vs. their dimerization products with increments ranging from 2.97 kcal mol–1 (N-methyl) to as high as 6.28 kcal mol–1 (N-tert-butyl). For combinations of N-methyl, N-ethyl and N-isopropyl substituents, the increments are additive and the dimerization energies were found to be free of noticeably steric effects. Significant steric strain was found for all tBu-substituted carbenes with strain energies of the dimerization products ranging from 6.92 kcal mol–1 [formation of (E)-Me2tBu2-enetetramine] to 24.23 kcal mol–1 (formation of tBu4 enetetramine). The tert-butyl substituent thus assumes a unique position by strongly stabilizing the carbenes electronically as well as sterically.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)

The thermodynamic stabilities of P2, P4, and three P8 cage structure were investigated through high-precision CBS-Q calculations. The CBS-Q values for the bond energy of P2 (ΔEo: +115.7 kcal mol−1) and the formation of P4 from P2 (Δ Eo:-56.6 kcal mol−1) were in excellent agreement with the experimental values (Eo: +117 and -56.4 kcal mol−1 respectively). Among the P8 cages, the cubane structure was the least stable (Δ Eo +37 kcal vs. 2×P4). The most stable P8 isomer adopts a cuneane structure resembling S4N4, and is more stable than white phosphorus at T = 0 K (Δ Eo −3.3 kcal mol−1), but still unstable under standard conditions for entropic reasons (Δ Go of +8.1 kcal mol−1 vs. 2×P4). The CBS-Q energies represent significant revisions (6–20 kcal mol−1) of previous computational predictions obtained by high-level single method calculations. © 2005 Wiley Periodicals, Inc. Heteroatom Chem 16:453–457, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20119

The reaction of primary amines RNH 2 (R: Me, Et, i Pr, t Bu and Ph) with 1,2-dibromoethane gave N , N ′-disubstituted ethylenediamines R–NH–CH 2 CH 2 –NH–R ( 1 ) in yields ranging from 10% ( 1a ; R=Me) to 70% ( 1d , R= t Bu; 1e , R=Ph). Piperazines and N -substituted polyethyleneimines were identified ( 1 H NMR, 13 C NMR and EI-MS) as side products of the reaction and isolated by fractional distillation. The piperazines 2 are formed in yields of 3–10% and can be separated from the diamines 1 in all cases, except for R=Me and Ph. The polyamine homologues RNH–[CH 2 CH 2 NR] n –H ( 3 – 5 ) were isolated in yields ranging from 0.1% ( n =4, R= i Pr) to 14% ( n =2, R= i Pr). The yields of 1 increase with the size of the substituent R, no obvious trend exists for the yields of the side products.

Selenoureas are obtained by a novel three-component condensation reaction from metallic selenium, triethyl orthoformate and a primary or secondary amine. The reaction is carried out as solvent-free one pot-procedure at 180–190°C under inert gas with a reaction time of 8 h. The reaction was tested for piperidine, isopropylamine, N,N′-dimethylpropylenediamine (Me-NH-CH2-CH2-CH2-NH-Me) and N,N′-disubstituted ethylenediamines (R-NH-CH2-CH2-NH-R, R=Me, Et, iPr, tBu, Ph).

An inner shell electron energy loss spectrometer (ISEELS) has been adapted as a probe of chemical reactions by coupling its gas phase interaction region to the output of a variety of chemical reactors including thermolysis, gas phase reaction, and heterogeneous reaction systems. Three examples of transient ISEELS studies are presented: in situ generation of a reactive carbene by thermolysis of its stable dimer, reaction of a silylene with N 2 O in the gas phase, and the heterogeneous reactions of H 2 S and H 2 O with crystalline boron in a heated quartz tube. In the latter example, temperature dependent inner shell excitation spectra, mass spectrometry and ab initio calculations were used to show that in the high temperature limit the reaction of H 2 S (g) and B (s) over SiO 2 (s) gives rise to borine (HBO), a species previously un-detected from this reaction chemistry.

The reactivities of the two stable diamino carbenes 1,3-di-tert-butylimidazol-2-ylidene (1) and 1,3-di-tert-butylimidazolin-2-ylidene (2) toward hydrogen, oxygen, water and carbon monoxide were investigated. The carbenes do not react with O2 or CO but are attacked by water to give the respective hydrolysis products tBu–NCHCH2–N(CHO)tBu (7) and tBu–NH–CH2CH2–N(CHO)tBu (8). While 2 is hydrolyzed instantaneously, the aromatically stabilized 1 reacts only very slowly and can be handled in air for brief periods of time. The carbenes 1 and 2 are unreactive towards H2 alone but can be catalytically hydrogenated to the respective aminals 2,3-dihydro-1,3-di-tert-butylimidazole (5) and 1,3-di-tert-butylimidazolidine (6). The reaction products were characterized by single crystal X-ray crystallography, multinuclear NMR spectroscopy (1H, 13C, 17O), IR spectroscopy and DFT methods. The extent of aromatic delocalization in 1 was investigated through isodesmic hydrogenation reactions at the B3LYP/6-31G(d)//B3LYP/6-31G(d) level. At this level of theory, the ‘carbene oxide’ (2,3-dihydro-imidazol-2-one) retains ca. 50% of the aromatic delocalization energy of the carbene. The oxidation of the diamino carbenes to the ‘carbene oxides’ (ureas) is calculated to be exothermic by −79.1 kcal mol−1 (1) and −86.4 kcal mol−1 (2). The oxygen affinity of the carbenes resembles that of trimethylphosphine (−79.7 kcal mol−1) and triethyl phosphite (−88.6 kcal mol−1) and is significantly higher than that of CO (−67.6 kcal mol−1). The aminals 5 and 6 are structurally related to Thauer's hydrogenase (TH2/TH+) but do not show hydrogenase activity.

The Raman, IR and UV spectra of the silylene ( t BuNCH CHN t Bu)Si: ( 1 ) as well as the Raman spectra of related compounds with tetravalent silicon ( t BuNCH CHN t Bu) 2 Si ( 2 ) and ( t BuNCH CHN t Bu)SiCl 2 ( 3 ) and of the heterocycle ( t BuNCH CHN t Bu)C O ( 4 ) are reported. Comparison of the spectra obtained for 1 – 3 reveals a lowered frequency and greatly enhanced intensity of the Raman band corresponding to the C C stretching vibration in the spectrum of 1 which is in accord with the aromatic character of the silylene.

The aromatic ring protons in imidazol-2-ylidenes (Arduengo carbenes) undergo rapid deuterium–hydrogen exchange in DMSO-d6, CD3OD and D2O.

A number of tert-butyl-substituted, cyclic, saturated and unsaturated diaminocarbene, diaminosilylene, and diaminogermylene compounds were investigated using inner shell electron energy loss spectroscopy (ISEELS) and ab initio calculations. These compounds, each of which contains a divalent group 14 element (C, Si, Ge), are of particular interest since they are stable indefinitely, and thus, they are readily accessible for detailed spectroscopic analysis. The C 1s and N 1s spectra of the hydrogenated tetravalent analogues of the saturated carbene, of di-tert-butyldiazabutadiene, and of di-tert-butyldiazabutane were also obtained to assist with spectral interpretation. Our analysis shows that there is significant π-allyl delocalization over the N−EII−N fragment in all three species. Further, in the unsaturated species there is additional aromatic delocalization. Both theory and experiment indicate that the divalent center of the carbene is qualitatively different from that in the germylenes or silylenes.

Contrary to earlier studies, mixtures of enetetramines A=A and B=B readily exchange their carbene units upon heating (100 – 175 °C) to give the cross-over olefins A=B. The absence of such exchange reactions has formerly been used as evidence against the dissociation of enetetramines into free carbenes by Lemal et al. and Winberg et al.

The aromatic stabilization of cyclic phosphenium cations (general type C2N2P+) was studied by experimental methods (synthesis, multinuclear NMR, single crystal X-ray crystallography) and quantum chemical calculations (ab initio methods). The structures of the 1,3,2-diazaphosphole derivatives [(tBuN–CH=CH–NtBu)P+]Cl− (1), (tBuN–CH2–CH2–NtBu)P–Cl (2), [(tBuN–CH=CH–NtBu)P]+PF6− (3) and [(tBuN–CH2–CH2-NtBu)]P+PF6− (4) were examined by single crystal X-ray diffraction. The chloro phosphane [(tBuN–CH=CH–NtBu)P]+Cl− (1) has an ionic P–Cl bond and contains an aromatically stabilized phosphenium cation [shortest distance P···Cl = 275.9(2) pm], while the CC-saturated compound (tBuN–CH2–CH2–NtBu)P–Cl (2) is covalent. The two chloro-phosphanes 1 and 2 differ sharply in their volatility and solubility in organic solvents. Compound 2 is soluble in hydrocarbons and sublimes readily at 90 °C/0.1 Torr but 1 is insoluble in hexanes and not volatile below 180 °C/0.1 Torr. The degree of aromatic stabilization in the phosphenium cation 1 was investigated by ab initio methods. For the model cations [RN–CH2–CH2–NR]P+ and [(RN–CH=CH–NR)P]+, thermochemical stabilization energies of 25.8 kcal · mol−1 (R = H) and 28.1 kcal · mol−1 (R = Me) were obtained from isodesmic hydrogenation reactions at the RHF/MP2/6–31G*//RHF/6–31G* level.

The reaction of the stable silylene 1 (L′Si:) with CO, SnCl2, PbCl2, the stable carbene L′C: (2) and the stable germylene L′Ge: (3) was investigated as a possible approach for the synthesis of hetero-polysilanes (poly-carbosilanes, poly-germasilanes, poly-stannasilanes). The silylene 1 was found to be inert towards all substrates except SnCl2 and PbCl2. Reaction with SnCl2 led to the formation of the yellow, tris(silyl)stannane [(L′SiCl)3SnCl] (5) and elemental tin. The photolabile (5) was characterized by multinuclear NMR (1H, 13C, 29Si, 119Sn) and single crystal X-ray diffraction: C30H60Cl4N6Si3Sn, M = 849.60, orthorhombic, space group Pca21. The bond angles of 115.89 ° (ave. Si–Sn–Si) and 101.87 ° (ave. Cl–Sn–Si) show a slightly flattened tetrahedral geometry around the tin atom. – Thermolysis of 5 at 100 °C led to the deposition of thin films of tin; photolysis resulted in the formation of tin powder. All thermolysis products could be isolated and were characterized as SnCl2, elemental tin, L′Si: (1), L′SiCl2 (6) and the new disilane L′Si(Cl)-(Cl)SiL′ (7). Photolysis led to a reduced product spectrum (formation of Sn + SnCl2 + 7). Reaction of 1 with PbCl2 gave elemental lead and L′SiCl2 as the only products.

The silicon 1s, 2p, and 2s, carbon 1s, and nitrogen 1s gas-phase core excitation spectra are reported for two stable divalent silylenes, Si(NRCHCHNR) and Si(NRCH2CH2NR) (R = tBu), and for the two analogous tetravalent dihydridosilane molecules, H2Si(NRCHCHNR) and H2Si(NRCH2CH2NR) (R = tBu). The nature of the excited states arising from one-electron core → π* and core → σ* excitations at different sites on the silylene ring are examined by relating the changes in the spectra of these compounds to differences in their molecular structure. The variations in the intensities of core → π* transitions in these spectra probe the extent of delocalization in the π-electron manifold and, thus, allow us to investigate the nature of π stabilization in heterocycles containing divalent silicon. Low-lying transitions to a π*(Si−N) level observed in all core edge spectra strongly support the existence of π-delocalization in the CC unsaturated silylene. Ab initio calculations are used to confirm spectral assignments.

The alkylation of ethylenethiourea with alcohols and aqueous acids (HCl, HBr, and HI) allows the synthesis of the respective S-alkyl-isothioureas in high yield and purity. Consistently high yields (91–98%) were obtained with 56% HI, the yields for 48% HBr (48–93%) and 37% HCl (36–85%) were lower and varied with the type of alcohol. The method is a convenient low-cost alternative to the use of alkyl iodides and an easy access to the S-tert-butyl isothiourea.

Silylenes, R2Si: are the silicon counterparts to carbenes of organic chemistry. However, they play an even more important role in silicon chemistry than carbenes do in carbon chemistry. Silylenes are key intermediates in many thermal and photochemical reactions of organosilicon compounds. (1) Many silylenes have now been observed and identified when isolated in argon

We report the successful synthesis and structural characterization of quadrivalent tetrahydroborate complexes of titanium and zirconium, stabilized by a chelating bis-imine. Whereas the titanium compound 3a displays an unusual η2,η3-coordination of the tetrahydroborate ligands, the zirconium congener 3b adopts the η3,η3-coordination known from the homoleptic complex [Zr(BH4)4].

The ionic chlorophosphane [L′P] + Cl − ( 1 ) was obtained for the ligand L′ = N,N′-bis (tert- butyl)-1,4-diaza-2- butene . By contrast, the CC-saturated analog LP-Cl ( 2 , L = N,N′-bis (tert- butyl)-1,4-diaza-2- butane ) is covalent. This remarkable difference can be attributed to the fact that the phosphenium cation derived from 1 possesses aromatic 6π-stabilization. As expected, the two chlorophosphanes differ sharply in their volatility and solubility in organic solvents.

The silylene–borane adduct 2 is formed from the corresponding silylene and tris(pentafluorophenyl)borane and rearranges to silylborane 3 with a half-life of about one month in toluene.

Background: The purpose of this study was to evaluate the noninvasive coronary angiography method in innovative minimally invasive coronary surgery as an approach to optimal quality control. Methods: Between July 2005 and September 2009, 180 consecutive patients (64±12 years; w/m: 53/127) underwent beating-heart minimally invasive bypass surgery via reversed-J inferior mini-sternotomy approach. Internal thoracic arteries (ITAs) were skeletonized with harmonic scalpel. For detection of intraoperative early graft occlusion, flow in the bypass grafts was routinely measured with the transit-time method. To evaluate the quality of the ITA-grafts and the anastomoses, contrast-enhanced 64-slice multi-detector row computed tomography (MDCT, cardiac CT) was performed in 168 patients (93.3%) between 5th and 7th postoperative day. Results: Intraoperative transit-time flow measurement detected a need of revision graft failure. The mean flow within the ITA was 40±20ml/min. Re-interventions were necessary in 6 cases (3.3%) between 1st and 4th day after surgery. Three cases of revisions (1.7%) were postoperative ITA-graft failures revealed by Cardiac CT: dissection, kinking, and twisting. All other grafts were patent and could be demonstrated on 3-D reconstruction. Additionally there were 3 re-interventions because of acute thrombotic total occlusion of intracoronary stents in left circumflex and right coronary arteries. Conclusions: Multislice cardiac CT seems to be an attractive non-invasive tool for visualization of graft patency after coronary surgery. The combination of intraoperative flow measurement and postoperative non-invasive cardiac CT allows high-quality evaluation of immediate and short-term outcome in innovative minimally invasive coronary surgery.

Complexes of the Lanthanides, III[1]. – Volatile Neodymium and Yttrium Alkoxides with New Bulky Chelating Ligands The synthesis of a new type of lanthanide alkoxides is described. The “clinching alcohols” HOCHtBuCH2OEt (1a), HOCHtBuCH2NEt2 (1b), HOCtBu2CH2OEt (1c), and HOCH-i Pr2CH2OEt (1d) react with Nd[N{Si(CH3)3}2]3 (2a) to form the corresponding homoleptic alkoxide complexes 3a–d. The same procedure is applied to obtain the novel yttrium alkoxide 4 from the amide precursor 2b and the alcohol 1d. The new complexes are all very soluble in aliphatic hydrocarbons and were characterized by means of analyses and spectroscopy. The interesting property of these complexes is their remarkable volatility, the highest so far achieved for lanthanide alkoxides.

Methylation of the nitridomolybdenum(VI) complex NMo(O-t-C4H9)3 2, obtained from NMoCl3· THF (1), is achieved by use of dimethylzinc, resulting in the formation of the novel tetranuclear products [N Mo(CH3)2(O-t-C4H9) · 1 2 py]4 (3) (py = 4-t-butylpyridine). A single-crystal X-ray diffraction study reveals four NMo(CH3)2 units being connected through the nitrogen atoms, thereby forming unsymmetrical, linear MoN-Mo units. The cubane-type zinc complex [CH3ZnO-t-C4H9]4 (4; X-ray diffraction study) is also formed.

BACKGROUND: Selective skeletonization of the internal mammary artery (IMA) without adjacent vasculo-muscular structures reduces trauma to the chest wall, results in elongated grafts, makes ideal graft positioning possible, and eliminates the need to implant a dissected or hypoplastic graft with direct visual control of the vessel. We compared two techniques of skeletonizing the IMA in a prospective randomized trial. METHODS: 51 IMAs were randomly harvested and divided into two groups according to the technique of skeletonization. In group I (n = 31), IMAs were harvested in a skeletonized fashion with the Harmonic Ultrasonic scalpel, and in group II (n = 20) using scissors and hemostatic clips. We compared arterial wall histology, harvesting time, spasm frequency, and the use of hemostatic clips between the two groups. RESULTS: There were no significant morphological differences in the arterial wall in the two groups. Use of an ultrasonically-activated scalpel reduced the IMA's harvesting time ( P < 0.001), the frequency of spasm ( P = 0.01), and the use of hemostatic clips ( P < 0.001). CONCLUSIONS: Ultrasonic harvesting of a skeletonized IMA is a non-traumatic preparatory technique that reduces the costs of surgical clips and that can be performed safely and quickly.