Search

Amino-substituted thio(seleno)acrylamides were synthesized in a study and their (super1)H and (super 13)C NMR spectra assigned. Both the NMR data and the results of theoretical calculations at the ab initio level of theory were used to explain the adopted structures of the compounds in terms of E/Z isomerism, and s-cis/s-trans configuration.

Carbonyl core (C 1S, O1S) --> pi c=o transitions are distinctive in the near-edge X-ray absorption fine structure (NEXAFS) spectra of organic molecules. The chemical sensitivity of these features in C 1s and O 1s NEXAFS spectra is explored for a series of polymers containing the carbonyl group.

The combination of infrared, FT-Raman and inelastic neutron scattering spectrodcopies to test and extend previous assignments. The FT-Raman spectra show all of the carbonyl stretching modes for the first time and these are assigned by comparison of the DFT calculations.

Mass-selected ion infrared spectroscopy in the C-O stretching region is used for analyzing uranium and uranium dioxide carbonyl cations produced by laser vaporization. Back-bonding in U[(CO).sub.8.sup+] has caused a red-shifted CO stretch, but back-donation is inefficient for U[O.sub.2][(CO).sub.5.sup.+], which has produced a blue-shifted CO stretch characteristic of nonclassical carbonyls.

The article explains the synthesis, as well as the properties of a ratiometric fluorescent chemodosimeter, which is shown to contain a guanidiniocarbonylpyrrole and a 9-(aminomethyl)anthracene moiety. The selective recognition of the compound for sulfite in the aqueous solution is also discussed.

The preparation and IR laser photodissociation spectroscopic studies of gas-phase metal carbonyl cations of the vanadium-group metals (V(+), Nb(+), Ta(+)) in the carbonyl-stretching region is described. The IR spectra of V and Nb{V[(CO).sub.6.sup.+]) and Nb[(CO).sub.6.sup.+]} showed six-coordinated structures slightly distorted from octahedral while Nb and Ta {Nb[(CO).sub.7.sup.+] and Ta[(CO).sub.7.sup.+]} exhibited seven-coordinated [C.sub.3v] capped octahedral structures.

The studies on NIS/AgOTf-promoted glycosylations with ethyl 2,3-N,O-carbonyl-2-deoxy-1-thio-[beta]-D-glucopyranoside donors performed by using either [alpha]- or [beta]-selectivity is reported. NMR-monitored glycosylation and anomerization experiments revealed that the initial formation of [beta]-linkage, which anomerizes through an intramolecular mechanism involved an endocyclic C-O bond cleavage, to the [alpha]-linkage.

An ultrafast broadband transient absorption spectroscopy was used to study the direct photolysis of oxetane DMT-BP, which is the oxetane adduct of 1,3-dimethylthymine (DMT) with benzophenone (BP). The results offer insight into the cycloreversion reaction that occurs in a stepwise manner on a singlet excited-state followed by intersystem crossing (ISC) to form the triplet carbonyl product.

A group of robust and easy-to-make photolabile protecting groups (PPGs) for carbonyl compounds is developed. The sequential removal of different PPGs is achieved by controlling irradiation wavelength.

The frequency-resolved sub-picosecond infrared spectroscopy is employed to study the ultrafast dynamics of the carbonyl CO stretching vibration in acetic acid in aqueous solution. The two acetic acid components are shown to exhibit almost similar bond shape and time constants.

A simple and highly efficient method for the rearrangement of bromohydrins mediated by [Et.sub.2]Zn to prepare carbonyl compounds is described. The method helps to obtained acyclic and cyclic bromohydrins and a variety of ring-expansive and -contractive carbonyl compounds.

A scalable synthesis of 2,2-difluorohomopropargyl esters is obtained by using a magnesium-promoted Barbier reaction of substituted difluoropropargyl bromides with alkyl chloroformates. The [2 + 2 + 2] cycloaddition of alkynes with fluorinated 1,7-diyne amides has given 4,4-difluoro-1,4-dihydro-3(2H)-isoquinolinone derivatives regioselectively.

The ultrafast time-resolved ultraviolet-visible (UV-vis) and infrared (IR) spectroscopies are used for studying a simple aryl diazo ketone to assess the relative importance of these processes to the light induced formation of ketenes from a diazo carbonyl precursor. The photolysis of the conformer of the precursor has led to the formation of hot ketene from [super 1]BpC[N.sub.2]COC[H.sub.3]* by Wolff Rearrangement (WR) in concert with nitrogen extrusion.

A combination of photoelectron spectroscopy (PES) and synchrotron radiation in the valence region were employed to study the small penta-atomic molecules like FC(O)SCl and ClC(O)SCl. The results provided insight into electronic properties and the ionization channels of both species.

The infra red photodissociation spectroscopic studies of nonclassical [Au.sup.+] [(CO).sub.n] (n = 3-7) species in the gas-phase is demonstrated. The carbonyl stretch observed in blue-shift 50-100 [cm.sup.-1] with respect to the free CO vibration confirms the species as nonclassical metal carbonyls.

A new synthesis method is described for the aziridine required for the aziridine-[pi]-nucleophile cyclization for preparing 6-azabicyclo[3.2.1]octanes. The studies have shown that N-diphenylphospinyl and N-H aziridines have not led to the desired bicyclic ring systems, whereas a nosyl group on the aziridine nitrogen has led to the bicyclic ring system.

Ultrafast two-dimensional infrared (2D IR) and visible pump-infrared probe (Vis-IR) spectroscopy are used for examining the dynamics of photoinduced charge separation and the motion of the resulting electrons in an organic photovoltaic material. The results have shown that organic solar cells with higher mobility and the efficiency are obtained by controlling the morphology of the polymer and fullerene materials.

The synthesis, spectroscopic characteristics, and electrochemistry of 2,3,9,10,16,17,24,25-octakis(octyloxycarbonyl)phthalocyanine compounds are discussed. Both electrochemical and theoretical calculation results reveal the electron-withdrawing nature of the octyloxycarbonyl groups attached onto the peripheral positions of phthalocyanine ring.

An exercise is described that has illustrated the effect of various factors on [pi] backbonding to carbonyl ligands, where the students can view the molecular orbitals corresponding to the M-CO [pi] interaction as well as the competing interaction between the metal and co-ligands. The visual and hands-on nature of the modeling exercise has helped students understand the d[pi]-p[pi]* backbonding and has further enforced the concepts of infrared (IR) spectroscopy.

Two equivalents of acetylacetone (acac) are introduced into a monomeric tungsten(II) coordination sphere and a tungsten(II) bis(acac) tricarbonyl complex, W(CO)3(acac)2, is formed with the tetracarbonyltriiodotungsten(II) anion as a precursor. X-ray crystallography has provided structural assignments for a representative molecule from each class of these complexes, and variable temperature NMR is used to detect the fluxional processes within this series of bis(acac) tungsten [d.sup.4] complexes.

[Li.sup.+] and [Ca.sup.+] binding to the carbonyl oxygen sites of a model peptide system is studied by [sup.17.O] solid-state NMR spectroscopy and [sup.17.O] chemical shift (CS) and quadrupole coupling (QC) tensors are determined in four Gly-(Gly-[sup.17.O])-Gly polymorphs by a combination of stationary and fast magic-angle spinning (MAS) methods at high magnetic field, 19.6 T. The effects of the ion binding are found to be almost an order of magnitude greater than those induced by hydrogen bonding.

The structures of iron pentacarbonyl, Fe(CO)5, solvated in benzene and its fluorinated derivatives are investigated by X-ray absorption fine structure (XAFS) spectroscopy and infrared (IR) spectroscopy as well as density functional theory (DFT) calculations. It is shown that fluorinated benzenes interact in a similar geometry through either hydrogen or fluorine.

Copper(I) carbonyl complexes of beta-diketiminate and of three less-fluorinated analogues; have been compared by IR specectroscopy. Ligand beta-diketiminate gives rise to stable benzene adducts, which react with O2, leading to ortho-hydroxylation of a ligand N-Ar(super f) group.

Thioacetalization is a reaction that protects carbonyl groups of aldehydes and ketones. A mechanism for this thioacetalization reaction is presented.

The nu (CO) infrared and Raman spectra of [Ag(sub 5)[u(sub 2)fe(CO)(sub 4)](sub 2)[u(sub 3)fe(CO)(sub 40](sub 2)](super 3), are presented. The nu (CO) vibrational spectra of planar transition cluster carbonyls containing M(CO)(sub 4) groups are studied.

The high resolution multibubble sonoluminescence (MBSL) spectra arising from the ultrasonic irradiation of metal carbonyls and other volatile metal- containing compounds dissolved in silicone oil saturated with helium or argon are reported. These MBSL spectra showed that the pressure within the bubble at the point of emission was on the order of 300 bar in argon- saturated silicone oil, which is consistent with simple adiabatic compression during cavitation.