The reaction of O(P) with alkynes: a dynamic and computational study focusing on formyl radical production.

Production of formyl radical, HCO, from reactions of O(P) with alkynes (acetylene, propyne, 1-butyne, and 1-pentyne) has been investigated using cavity ringdown laser absorption spectroscopy (CRDLAS) and computational methods. No HCO was detected from reaction with acetylene, while the amount of HCO increased for propyne and 1-butyne, dropping off somewhat for 1-pentyne. These results differ from trends previously observed for reactions of O(P) with alkenes, which exhibit the largest HCO production for the smallest alkene and drop off as the alkene size increases.

Integrating SERS and PSI-MS with Dual Purpose Plasmonic Paper Substrates for On-Site Illicit Drug Confirmation.

Forensic laboratory backlogs are replete with suspected drug samples. Shifting analysis toward the point of seizure would save significant time and public funds. Moreover, a two-tiered identification strategy for controlled substance testing that relies on two independent, discerning methods could entirely circumvent the need for forensic laboratory testing.

Effects of Solvation and Hydrogen Bond Formation on Singlet and Triplet Alkyl or Aryl Carbenes.

Formation of hydrogen-bonded complexes involving singlet and triplet alkyl or aryl carbenes and the impacts of solvation and hydrogen bonding upon the carbene singlet-triplet gaps have been investigated using computational methods. Single-point CCSD(T)-F12 and MRCI+Q methodologies have been employed with aug-cc-pVDZ and aug-cc-pVTZ basis sets to determine accurate singlet-triplet gaps of carbenes and hydrogen-bonded complexes involving carbenes, with geometries and vibrational frequencies obtained at the B3LYP-D3/aug-cc-pVTZ level. Using the PCM continuum solvent method and density functional theory (B3LYP/aug-cc-pVTZ), the singlet-triplet gaps of the carbenes are found to exhibit significant solvent effects; due its higher polarity, the singlet carbene is stabilized to a greater degree than the corresponding triplet carbene, impacting the singlet-triplet gap by as much as 4.

Multireference configuration interaction study of bromocarbenes.

Multireference configuration interaction (MRCI) calculations of the lowest singlet X(1A') and triplet ã((3)A'') states as well as the first excited singlet Ã((1)A'') state have been performed for a series of bromocarbenes: CHBr, CFBr, CClBr, CBr(2), and CIBr. The MRCI calculations were performed with correlation consistent basis sets of valence triple-ζ plus polarization quality, employing a full-valence active space of 18 electrons in 12 orbitals (12 and 9, respectively, for CHBr). Results obtained include equilibrium geometries and harmonic vibrational frequencies for each of the electronic states, along with ã((3)A'') ← X((1)A') singlet-triplet gaps and Ã((1)A'') ← X((1)A') transition energies.

Beta-amino alcohol derived beta-hydroxy- and beta-(o-diphenylphosphino)benzoyloxy(o-diphenylphosphino)benzamides: an ester-amide ligand structural model for the palladium-catalyzed allylic alkylation reaction.

A commercially available collection of beta-amino alcohols have been converted to their corresponding beta-hydroxy- and beta-(o-diphenylphosphino)benzoyloxy(o-diphenylphosphino)benzamides 11a-f and 12a-f and have been employed in the Tsuji-Trost asymmetric alkylation reaction with 1,3-diphenylpropenyl acetate. With the exception of ligands 11b and 11f, the beta-hydroxybenzoyloxy(o-diphenylphosphino)benzamide ligands 11a-f primarily afforded the (R)-enantiomer of the product. In contrast, the bis(phosphine) ligands 12a-f consistently afforded the (S)-enantiomer.

Catalytic dioxygen activation by (nitro)(meso-tetrakis(2-n-methylpyridyl)porphyrinato)cobalt(III) cation derivatives electrostatically immobilized in nafion films: an experimental and DFT investigation.

Complexes of the (nitro)( meso-tetrakis(2- N-methylpyridyl)porphyinato)cobalt(III) cation, [LCoTMpyP(2)(NO 2)] (4+), in which L = water or ethanol have been immobilized through ionic attraction within Nafion films (Naf). These immobilized six-coordinate species, [LCoTMPyP(2)(NO 2)/Naf], have been found to catalyze the oxidation of triphenylphosphine in ethanol solution by dioxygen, therefore retaining the capacity to activate dioxygen catalytically without an additional reducing agent as was previously observed in nonaqueous solution for the non-ionic (nitro)cobalt porphyrin analogs. Heating these immobilized six-coordinate species under vacuum conditions results in the formation of the five-coordinate nitro derivatives, [CoTMPyP(2)(NO 2)/Naf] at 85 degrees C and [CoTMPyP(2)/Naf] at 110 degrees C.

An ab initio and density functional theory study of the structure and bonding of sulfur ylides.

Sulfur ylides are useful synthetic intermediates that are formed from the interaction between singlet carbenes and sulfur-containing molecules. Partial double-bond character frequently has been proposed as a key contributor to the stability of sulfur ylides. Calculations at the B3LYP, MP2, and CCSD(T) levels of theory employing various basis sets have been performed on the sulfur ylides H(2)S-CH(2) and (CH(3))(2)S-CH(2) in order to investigate the structure and bonding of these systems.

A gas- and condensed-phase density functional study of donor-acceptor complexes of sulfur trioxide.

A series of donor-acceptor complexes containing sulfur trioxide have been studied in the gas and condensed phases using density functional theory. The condensed phase is represented using the polarizable continuum model. The systems investigated include complexes of nitrogen-containing donor molecules, (CH(3))(n)H(3-n)N (n = 0-3), with SO(3) and complexes of oxygen-containing donor molecules, (CH(3))(m)H(2-m)O (m = 0-2), with SO(3).

Toward the development of a structurally novel class of chiral auxiliaries. Conformational properties of the aldol adducts of oxadiazinones: observation of unusual shielding effects.

Asymmetric aldol reactions were conducted with the titanium enolate of N(3)-hydrocinnamoyl-3,4,5,6-tetrahydro-2H-1,3,4-oxadiazin-2-one to afford aldol adducts 5a-j. The dominant product of the asymmetric aldol reaction was the non-Evans syn adduct as determined by (1)H NMR spectroscopy and X-ray crystallography. When evaluating the (1)H NMR spectra of adducts 5a-j, a highly shielded signal with an average chemical shift of 0.

Conformational studies of N(3)-substituted [1,3,4]-oxadiazinan-2-ones.

Pseudoephedrine-based [1,3,4]-oxadiazinan-2-ones acylated at the N(3)-position with either acetyl (2a), propionyl (2b), or phenylacetyl (2c) substituents are known to undergo conformational changes that are observable by (13)C NMR spectroscopy. The conformational properties of new [1,3,4]-oxadiazinan-2-one derivatives 2d-k are examined by X-ray crystallography and variable-temperature (13)C NMR spectroscopy and further evaluated by semiempirical AM1 calculations. The collected data reveal that the conformational changes of the overall ring system are dependent upon the stereoelectronic factors of the N(3)-substituent.