@article {ENDO2020111348, title = {FTMW spectroscopy of epichlorohydrin: Detection of three conformers}, journal = {Journal of Molecular Spectroscopy}, volume = {372}, year = {2020}, pages = {111348}, abstract = {

Pure rotational transitions of three conformers of epichlorohydrin were observed. Among the three possible conformers expected for this species, spectra of the two chlorine isotopologues, 35Cl and 37Cl, have been detected for the two gauche-conformers, while only the 35Cl isotopologue was detected for the cis-conformer which is much higher in energy. Well resolved chlorine nuclear hyperfine splittings were observed for all the conformers and isotopologues, yielding precisely determined molecular constants.

}, keywords = {Conformations, Fourier transform microwave spectroscopy, Hyperfine interaction, molecular structure}, issn = {0022-2852}, doi = {https://doi.org/10.1016/j.jms.2020.111348}, url = {http://www.sciencedirect.com/science/article/pii/S0022285220301168}, author = {Yasuki Endo and Takamasa MOMOSE} } @article {Rueda-Becerril2012, title = {Fluorine transfer to alkyl radicals.}, journal = {J. Am. Chem. Soc.}, volume = {134}, number = {9}, year = {2012}, month = {mar}, pages = {4026{\textendash}9}, abstract = {The development of new synthetic technologies for the selective fluorination of organic compounds has increased with the escalating importance of fluorine-containing pharmaceuticals. Traditional methods potentially applicable to drug synthesis rely on the use of ionic forms of fluorine (F(-) or F(+)). Radical methods, while potentially attractive as a complementary approach, are hindered by a paucity of safe sources of atomic fluorine (F({\textbullet})). A new approach to alkyl fluorination has been developed that utilizes the reagent N-fluorobenzenesulfonimide as a fluorine transfer agent to alkyl radicals. This approach is successful for a broad range of alkyl radicals, including primary, secondary, tertiary, benzylic, and heteroatom-stabilized radicals. Furthermore, calculations reveal that fluorine-containing ionic reagents are likely candidates for further expansion of this approach to polar reaction media. The use of these reagents in alkyl radical fluorination has the potential to enable powerful new transformations that otherwise would take multiple synthetic steps.}, keywords = {Fluorinated, Fluorinated: chemical synthesis, Fluorinated: chemistry, FLUORINE, Fluorine: chemistry, Free Radicals, Free Radicals: chemical synthesis, Free Radicals: chemistry, HYDROCARBONS, models, MOLECULAR, molecular structure, quantum theory}, issn = {1520-5126}, doi = {10.1021/ja211679v}, url = {http://www.ncbi.nlm.nih.gov/pubmed/22320293}, author = {Rueda-Becerril, Montserrat and Sazepin, Claire Chatalova and Leung, Joe Cho Tak and Okbinoglu, Tulin and Kennepohl, Pierre and Paquin, Jean-Fran{\c c}ois and Sammis, Glenn M} } @article {Martin-Diaconescu2009, title = {Effects of hyperconjugation on the electronic structure and photoreactivity of organic sulfonyl chlorides.}, journal = {Inorg. Chem.}, volume = {48}, number = {3}, year = {2009}, month = {feb}, pages = {1038{\textendash}44}, publisher = {The University of British Columbia, Department of Chemistry, Vancouver, British Columbia V6T 1Z1.}, abstract = {The electronic structure of organic sulfonyl compounds of the form RSO(2)G (G = -Cl, -OH, -CH(3)) is investigated to evaluate the effect of aryl R groups on photocleavage of the S-G bond. Sulfur K-edge X-ray absorption spectroscopy (XAS) provides a direct measure of the empty low-lying molecular orbitals in these complexes and, in combination with DFT calculations, a detailed description of the bonding in these compounds. The presence of an aryl group bound to the sulfonyl moiety has a significant impact on the spectroscopy and electronic structure of the site. The analysis suggests that the SCl(sigma*) orbital is significantly affected by mixing with the aryl pi* manifold. This mixing is dependent upon the nature of G and is most pronounced in the sulfonyl chlorides, where the energy of the SCl(sigma*) orbital is lowered by approximately 0.5 eV. The observed mixing is best described as excited-state hyperconjugation of the aryl pi system into the SCl(sigma*) orbital. The magnitude of the effect can be estimated directly from the S K-edge XAS spectra. These results are discussed in relation to the observed photochemistry of RSO(2)Cl, which is significantly enhanced when R = aryl as compared to alkyl substituents.}, keywords = {DFT, ELECTRONS, models, MOLECULAR, molecular structure, Organic Chemicals, Organic Chemicals: chemistry, PHOTOCHEMISTRY, Spectrum Analysis, Sulfinic Acids, Sulfinic Acids: chemistry, sulfur redox, XAS}, issn = {1520-510X}, doi = {10.1021/ic801665f}, url = {http://pubs.acs.org/doi/abs/10.1021/ic50073a047 http://www.ncbi.nlm.nih.gov/pubmed/19132932}, author = {Martin-Diaconescu, Vlad and Kennepohl, Pierre} } @article {ISI:000254173600010, title = {N-heterocyclic carbene complexes of Rh: reaction with dioxygen without oxidation.}, journal = {J. Am. Chem. Soc.}, volume = {130}, number = {12}, year = {2008}, month = {mar}, pages = {3724{\textendash}5}, abstract = {The reaction of oxygen with rhodium complexes containing N-heterocyclic carbenes was found to give dioxygen complexes with rare square planar geometries and unusually short O-O bond lengths. Analysis of the bonding in these complexes by Rh L-edge X-ray absorption spectroscopy (XAS), Raman spectroscopy, and DFT calculations provides evidence for a bonding model in which singlet oxygen is bound to a Rh(I) d8 metal complex, rather than the more common Rh(III) d6 peroxo species with octahedral geometry and O-O bond lengths in the 1.4-1.5 A range.}, keywords = {chemical, DFT, dioxygen complexes, Heterocyclic Compounds, Heterocyclic Compounds: chemistry, METHANE, Methane: analogs \& derivatives, Methane: chemistry, models, MOLECULAR, molecular structure, ORGANOMETALLIC COMPOUNDS, Organometallic Compounds: chemical synthesis, Organometallic Compounds: chemistry, OXYGEN, Oxygen: chemistry, rhodium, Rhodium: chemistry, SPECTROMETRY, X-Ray Emission, X-Ray Emission: methods, XAS}, issn = {1520-5126}, doi = {10.1021/ja7108213}, url = {http://www.ncbi.nlm.nih.gov/pubmed/18321109}, author = {Praetorius, Jeremy M and Allen, Daryl P and Wang, Ruiyao and Webb, Jonathan D and Grein, Friedrich and Kennepohl, Pierre and Crudden, Cathleen M} } @article {ISI:000227764700020, title = {Spectroscopy of non-heme iron thiolate complexes: insight into the electronic structure of the low-spin active site of nitrile hydratase.}, journal = {Inorg. Chem.}, volume = {44}, number = {6}, year = {2005}, month = {mar}, pages = {1826{\textendash}36}, abstract = {Detailed spectroscopic and computational studies of the low-spin iron complexes [Fe(III)(S2(Me2)N3 (Pr,Pr))(N3)] (1) and [Fe(III)(S2(Me2)N3 (Pr,Pr))]1+ (2) were performed to investigate the unique electronic features of these species and their relation to the low-spin ferric active sites of nitrile hydratases. Low-temperature UV/vis/NIR and MCD spectra of 1 and 2 reflect electronic structures that are dominated by antibonding interactions of the Fe 3d manifold and the equatorial thiolate S 3p orbitals. The six-coordinate complex 1 exhibits a low-energy S(pi) {\textendash}> Fe 3d(xy) (approximately 13,000 cm(-1)) charge-transfer transition that results predominantly from the low energy of the singly occupied Fe 3d(xy) orbital, due to pure pi interactions between this acceptor orbital and both thiolate donor ligands in the equatorial plane. The 3d(pi) {\textendash}> 3d(sigma) ligand-field transitions in this species occur at higher energies (>15,000 cm(-1)), reflecting its near-octahedral symmetry. The Fe 3d(xz,yz) {\textendash}> Fe 3d(xy) (d(pi) {\textendash}> d(pi)) transition occurs in the near-IR and probes the Fe(III)-S pi-donor bond; this transition reveals vibronic structure that reflects the strength of this bond (nu(e) approximately 340 cm(-1)). In contrast, the ligand-field transitions of the five-coordinate complex 2 are generally at low energy, and the S(pi) {\textendash}> Fe charge-transfer transitions occur at much higher energies relative to those in 1. This reflects changes in thiolate bonding in the equatorial plane involving the Fe 3d(xy) and Fe 3d(x2-y2) orbitals. The spectroscopic data lead to a simple bonding model that focuses on the sigma and pi interactions between the ferric ion and the equatorial thiolate ligands, which depend on the S-Fe-S bond angle in each of the complexes. These electronic descriptions provide insight into the unusual S = 1/2 ground spin state of these complexes: the orientation of the thiolate ligands in these complexes restricts their pi-donor interactions to the equatorial plane and enforces a low-spin state. These anisotropic orbital considerations provide some intriguing insights into the possible electronic interactions at the active site of nitrile hydratases and form the foundation for further studies into these low-spin ferric enzymes.}, keywords = {BINDING SITES, Computational Biology, ELECTROCHEMISTRY, Ferric Compounds, Ferric Compounds: chemical synthesis, Ferric Compounds: chemistry, Hydro-Lyases, Hydro-Lyases: chemistry, iron, Iron: chemistry, models, MOLECULAR, Molecular Conformation, molecular structure, PhD, SPECTROPHOTOMETRY, Sulfhydryl Compounds, Sulfhydryl Compounds: chemistry}, issn = {0020-1669}, doi = {10.1021/ic0487068}, url = {http://www.ncbi.nlm.nih.gov/pubmed/15762709}, author = {Kennepohl, Pierre and Neese, Frank and Schweitzer, Dirk and Jackson, Henry L and Kovacs, Julie A and Solomon, Edward I} } @article {609, title = {Interaction of rhodium(I) bisphosphine complexes with semicarbazones to give orthometallated rhodium(III) complexes}, journal = {Russian Chemical Bulletin}, volume = {52}, number = {12}, year = {2003}, note = {ISI Document Delivery No.: 809IUTimes Cited: 7Cited Reference Count: 57International Memorial Symposium on Modern Trends in Organometallic and Catalytic Chemistry Dedicated to Mark Vol{\textquoteright}pinMAY 18-AUG 23, 2003Moscow, RUSSIA}, month = {Dec}, pages = {2707-2714}, type = {Proceedings Paper}, abstract = {Interaction of the cis-[Rh(PR3)(2)(Solv)(2)]PF6 complexes (R = Ar or R-3 = Ph2Me, Solv solvent) under Ar with semicarbazones bearing a phenyl group on the imine-C atom gives the rhodium(III)-hydrido-bis(phosphine)-orthometallated semicarbazone species [RhH(PR3)(2){(o-C6H4(R{\textquoteright})C=N-N(H)CONH2}]PF6 (R{\textquoteright} = Me or Et), which are characterized generally by elemental analysis, P-31{H-1} and H-1 NMR spectroscopy, and mass-spectrometry. The PPh3-containing complex with R{\textquoteright} = Me, structurally characterized by X-ray analysis, reveals coordination of the semicarbazone by the ortho-C atom, the imine-N atom, and the amide-carbonyl group. For a semicarbazone containing no Ph group, the rhodium(I) complex [Rh(PR3)(2)(Et(Me)C=N-N(H)CONH2)]PF6, containing the eta(2)-semicarbazone bonded via the imine-N and carbonyl, is formed. Attempts to hydrogenate the C=N moiety in the complexes or to catalytically hydrogenate the semicarbazones were unsuccessful.}, keywords = {ACTIVATION, ASYMMETRIC HYDROGENATION, BENZALDEHYDE SEMICARBAZONE, C-H, C-H BONDS, CATALYTIC-HYDROGENATION, COMPLEXES, CRYSTAL-STRUCTURE, FINE CHEMICALS, INTRAMOLECULAR ACTIVATION, molecular structure, orthometallation, phosphines, rhodium, SELECTIVE HYDROGENATION, semicarbazones, SYNTHESIS, TRANSITION-METAL-COMPLEXES, UNPRECEDENTED CHEMICAL TRANSFORMATION}, isbn = {1066-5285}, url = {://000220631200019}, author = {Ezhova, M. B. and Patrick, B. O. and James, Brian R. and Ford, M. E. and Waller, E. J.} } @article {5088, title = {Molecular structure and conformation of peroxydisulfuryl difluoride, S2O6F2, as determined by gas-phase electron diffraction and ab initio molecular orbital calculations}, journal = {Journal of Molecular Structure}, volume = {567}, year = {2001}, note = {ISI Document Delivery No.: 454MBTimes Cited: 3Cited Reference Count: 22Sp. Iss. SI}, month = {Jun}, pages = {1-10}, type = {Article}, abstract = {The structure and conformational composition of peroxydisulfuryl difluoride, S2O6F2, have been investigated by gas-phase electron diffraction. Some of the results from ab initio molecular orbital calculations (MP2/6-311 + G*) were used as constraints in the analysis. There is both experimental and theoretical evidence that only conformers with a gauche X-OO-X torsion angle are present in the gaseous sample. Of these, only two conformers of symmetry C-2 (G(+)G(+) and G(-)G(-)) and one of symmetry C-1 (G(+)G(-)), where G(+/-) designates positive/negative rotation around the O-S bonds at either end of the molecule) were found to be plausible components of the gaseous mixture. In experiments at 298 K, about equally good fits were found with two models, model A consisting of a ratio of G(-)G(-)/G(+)G(+) equal to 57/43 (2 sigma = 27), and model B consisting of a ratio of G(-)G(-)/G(+)G(-) equal to 38/62 (2 sigma = 14). The composition of model A corresponds to DeltaG(0) = G(0)(G(+)G(+)) = G(0)(G(-)G(-)) = 0.17 (sigma = 0.24) kcal/mol, and that of model B to DeltaG(0) = G(0)(G(+) G(-)) - G(o)(G(-)G(-)) = -0.29 (sigma = 0.12). A system composed of only C2 symmetry conformers, such as model A, is favored by IR and Raman data, but our electron-diffraction results do not allow a choice. However, the bond lengths and bond angles for all conformers are similar so that, except for the torsion angles, the parameter values for the G-G- form are also reasonably close to those in the other forms. These distances (r(g) (Angstrom)) and angles (angle (alpha) (degrees)) values with 2 sigma uncertainties are r(S=O)= 1.406(2) Angstrom, r(S-F)= 1.539(3) Angstrom, r(O-S) = 1.620(4) Angstrom, r(O-O)=1.453(14) Angstrom, (angle (O-S=O))= 1/2[(O-S=O-4)+ angle (O-S=O-5)] = 107.2(12)degrees Delta angle (O-S=O)= angle (O-S=O-4) - angle (O-S=O-9)= 8.10 (assumed), angle (O-S-F)= 98.2(18)degrees, angle (O-O-S)= 108.6(10)degrees angle (O=S=O)= 126.7(15)degrees, and angle (S-O-O-S)= 122.7(56)degrees. (C) 2001 Elsevier Science B.V. All rights reserved.}, keywords = {ab initio calculations, CLOSO2F, FOSO2F, molecular structure, PEROXIDE, peroxydisulfuryl difluoride, VIBRATIONAL-SPECTRA}, isbn = {0022-2860}, url = {://000169975400002}, author = {Hagen, K. and Hedberg, K. and Gard, G. and Aubke, F.} } @article {4676, title = {NMR and molecular structure of partially oriented mono and para methyl- and chlorobenzenes dissolved in nematic liquid crystals}, journal = {Canadian Journal of Chemistry-Revue Canadienne De Chimie}, volume = {77}, number = {11}, year = {1999}, note = {ISI Document Delivery No.: 253FETimes Cited: 8Cited Reference Count: 69}, month = {Nov}, pages = {1761-1774}, type = {Article}, abstract = {Spectral parameters, order parameters, and structural parameters, including the vibrationally corrected r(alpha) structure of the partially oriented solutes p-xylene, p-chlorotoluene, p-dichlorobenzene, toluene, and chlorobenzene dissolved in three liquid crystal mixtures, are reported. For samples containing the three solutes p-xylene, p-dichlorobenzene, and 1,3,5-trichlorobenzene, multiple quantum (MQ) nuclear magnetic resonance was used to aid in the analysis of the complex high-resolution spectra of the g-xylene. The high-resolution spectra of 1,3,5-trichlorobenzene and p-dichlorobenzene were easily identified and analyzed once the calculated p-xylene spectrum was subtracted from the experimental one. The methyl groups of p-xylene, p-chlorotoluene, and toluene have similar geometries when the structure is determined from dipolar couplings corrected for harmonic vibrations.}, keywords = {ELECTRIC-DIPOLE INTERACTIONS, EXCITATION, H-2 NMR, MAGNETIC-RESONANCE, MEAN TORQUE, molecular structure, MULTIPLE-QUANTUM NMR, nematic liquid crystal, NMR, ORDER MATRIX, order parameter, SELECTIVE, SOLUTES, SOLVENTS, SPECTRA}, isbn = {0008-4042}, url = {://000083545300009}, author = {Syvitski, R. T. and Burnell, E. E.} } @article {7788, title = {The microwave spectrum, structure and nuclear quadrupole coupling constants of sulphuryl chloride fluoride, SO2CIF}, journal = {Chemical Physics Letters}, volume = {9}, number = {6}, year = {1971}, note = {ISI Document Delivery No.: V44LRTimes Cited: 0Cited Reference Count: 14Holt, C. W. Gerry, M. C. L.}, month = {Jun}, pages = {621-623}, type = {Article}, abstract = {The microwave rotational spectra of the two most abundant isotopic species of sulphuryl chloride fluoride have yielded rotational constants, nuclear quadrupole coupling constants and the internuclear parameters.}, keywords = {CHLORURE, ELECTRON DIFFRACTION, molecular structure, ROTATION, SULPHURYL CHLORIDE}, isbn = {0009-2614}, url = {://000203004700038}, author = {Holt, C. W. and Gerry, M. C. L.} }