Search results for "Halogen"
showing 10 items of 434 documents
Brominated flame retardants and organochlorines in the European environment using great tit eggs as a biomonitoring tool
2009
Large-scale studies are essential to assess the emission patterns and spatial distribution of organohalogenated pollutants (OHPs) in the environment. Bird eggs have several advantages compared to other environmental media which have previously been used to map the distribution of OHPs. In this study, large-scale geographical variation in the occurrence of OHPs, such as polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs) and organochlorine pesticides (OCPs), was investigated throughout Europe using eggs of a terrestrial residential passerine species, the great tit (Parus major). Great tit eggs from 22 sampling sites, involving urban, rural and remote areas, in 14 Europea…
New Approach to 1,4-Benzoxazin-3-ones by Electrochemical C-H Amination.
2017
1,4-Benzoxazin-3-ones are important structural motifs in natural products and bioactive compounds. Usually the synthesis of benzoxazinones requires transition metal catalysts and pre-functionalized substrates, e.g. aryl halides. However, the anodic C,H amination of phenoxy acetates offers a very efficient and sustainable access to these heterocycles. The herein presented electrochemical protocol can be applied to a broad scope of alkylated substrates. Even tert-butyl moieties or halogen substituents are compatible with this versatile method.
A Novel Cathode Material for Cathodic Dehalogenation of 1,1-Dibromo Cyclopropane Derivatives.
2015
Leaded bronze turned out to be an excellent cathode material for the dehalogenation reaction of cyclopropanes without affecting the strained molecular entity. With this particular alloy, beneficial properties of lead cathodes are conserved, whereas the corrosion of cathode is efficiently suppressed. The solvent in the electrolyte determines whether a complete debromination reaction is achieved or if the process can be selectively stopped at the monobromo cyclopropane intermediate. The electroorganic conversion tolerates a variety of functional groups and can be conducted at rather complex substrates like cyclosporine A. This approach allows the sustainable preparation of cyclopropane deriva…
Frontispiece: A Novel Cathode Material for Cathodic Dehalogenation of 1,1‐Dibromo Cyclopropane Derivatives
2015
Structure and physical properties of [mu-tris(1,4-bis(tetrazol-1-yl)butane-N4,N4 ')iron(II)] bis(hexafluorophosphate), a new Fe(II) spin-crossover co…
2004
[mu-Tris(1,4-bis(tetrazol-1-yl)butane-N4,N4')iron(II)] bis(hexafluorophosphate), [Fe(btzb)(3)](PF6)(2), crystallizes in a three-dimensional 3-fold interlocked structure featuring a sharp two-step spin-crossover behavior. The spin conversion takes place between 164 and 182 K showing a discontinuity at about T-1/2 = 174 K and a hysteresis of about 4 K between T-1/2 and the low-spin state. The spin transition has been independently followed by magnetic susceptibility measurements, Fe-57-Mossbauer spectroscopy, and variable temperature far and midrange FIR spectroscopy. The title compound crystallizes in the trigonal space group P (3) over bar (No. 147) with a unit cell content of one formula u…
Halogen Bonding beyond Crystals in Materials Science
2019
Halogen bonding has recently gained well deserved attention in present-day research for its importance in many fields of supramolecular science and crystal engineering. Although generally overlooked in comprehensive studies in the past, halogen bonding has become an important tool also in the field of materials science. An increased number of scientific reports are published every year where halogen bonding is exploited in soft materials rather than in crystal engineering. Here, we focus on a description of the most exciting contemporary developments in the field of halogen-bonded functional soft materials, assembled using the guiding principles of crystal engineering. We give a particular …
Carbonyl Hypoiodites as Extremely Strong Halogen Bond Donors
2021
Abstract Neutral halogen‐bonded O−I−N complexes were prepared from in situ formed carbonyl hypoiodites and aromatic organic bases. The carbonyl hypoiodites have a strongly polarized iodine atom with larger σ‐holes than any known uncharged halogen bond donor. Modulating the Lewis basicity of the selected pyridine derivatives and carboxylates leads to halogen‐bonded complexes where the classical O−I⋅⋅⋅N halogen bond transforms more into a halogen‐bonded COO−⋅⋅⋅I−N+ ion‐pair (salt) with an asymmetric O−I−N moiety. X‐ray analyses, NMR studies, and calculations reveal the halogen bonding geometries of the carbonyl hypoiodite‐based O−I−N complexes, confirming that in the solid‐state the iodine at…
Classics Meet Classics: Theoretical and Experimental Studies of Halogen Bonding in Adducts of Platinum(II) 1,5-Cyclooctadiene Halide Complexes with D…
2021
Complexes of PtX2COD (X = Cl, Br, I; COD = 1,5-cyclooctadiene) were cocrystallized with classical halogen-bond donors (CHI3, I2, and 1,4-diiodotetrafluorobenzene (FIB)), resulting in noncovalently ...
Fine-tuning halogen bonding properties of diiodine through halogen–halogen charge transfer – extended [Ru(2,2′-bipyridine)(CO)2X2]·I2 systems (X = Cl…
2016
The current paper introduces the use of carbonyl containing ruthenium complexes, [Ru(bpy)(CO)2X2] (X = Cl, Br, I), as halogen bond acceptors for a I2 halogen bond donor. In all structures, the metal coordinated halogenido ligand acts as the actual halogen bond acceptor. Diiodine, I2, molecules are connected to the metal complexes through both ends of the molecule forming bridges between the complexes. Due to the charge transfer from Ru–X to I2, formation of the first Ru–X⋯I2 contact tends to generate a negative charge on I2 and redistribute the electron density anisotropically. If the initial Ru–X⋯IA–IB interaction causes a notable change in the electron density of I2, the increased negativ…
Tridentate C–I⋯O−–N+ halogen bonds
2017
The X-ray structures of the first co-crystals where the three oxygen lone pairs in N-oxides are fully utilized for tridentate C–I⋯O−–N+ halogen bonding with 1,ω-diiodoperfluoroalkanes are reported, studied computationally, and compared with the corresponding silver(I) N-oxide complexes.