@article {1302, title = {Photochemistry of 1-isopropylcycloalkyl aryl ketones: Ring size effects, medium effects, and asymmetric induction}, journal = {Organic Letters}, volume = {7}, number = {7}, year = {2005}, note = {ISI Document Delivery No.: 910HITimes Cited: 16Cited Reference Count: 15}, month = {Mar}, pages = {1315-1318}, type = {Article}, abstract = {The n = 0, 1, and 2 ketones shown above undergo Yang photocyclization in solution, but only the n = 1 analogues react this way in the solid state. Based on X-ray crystallography, these differences in reactivity are attributed to an unusually large distance for 1,4-hydroxybiradical cyclization in the solid state for the n = 0 and 2 ring systems, which leads to predominant reverse hydrogen transfer (rht). Enantiomeric excesses of up to 99\% can be achieved in the case of the n = 1 system through the use of the solid-state ionic chiral auxiliary method of asymmetric synthesis.}, keywords = {ABSTRACTION, BEHAVIOR, PHENYL KETONES, SALTS, STATE}, isbn = {1523-7060}, url = {://000227921200030}, author = {Xia, W. J. and Scheffer, J. R. and Botoshansky, M. and Kaftory, M.} } @article {532, title = {Enhanced regioselectivity of Yang photocyclization in the crystalline state}, journal = {Organic Letters}, volume = {4}, number = {7}, year = {2002}, note = {ISI Document Delivery No.: 536BDTimes Cited: 9Cited Reference Count: 13}, month = {Apr}, pages = {1071-1074}, type = {Article}, abstract = {[GRAPHICS] In contrast to the solution state, where Yang photocyclization of ketones of general structure 1 leads to equal amounts of cyclobutanols 2 and 3 (by abstraction of H-A and H-B, respectively), irradiation in the crystalline state is much more regioselective, favoring either 2 or 3 depending on the nature of the substituent X. X-ray crystallography and molecular mechanics calculations reveal the source of this remarkable solid-state regioselectivity.}, keywords = {ABSTRACTION, GAMMA, GEOMETRIC REQUIREMENTS, II REACTION, PHOTOCHEMISTRY, SOLID-STATE}, isbn = {1523-7060}, url = {://000174680100006}, author = {Vishnumurthy, K. and Cheung, E. and Scheffer, J. R. and Scott, C.} } @article {4766, title = {An investigation of the solid-state photochemistry of alpha-mesitylacetophenone derivatives: Asymmetric induction studies and crystal structure-reactivity relationships}, journal = {Tetrahedron}, volume = {56}, number = {36}, year = {2000}, note = {ISI Document Delivery No.: 351GHTimes Cited: 10Cited Reference Count: 24}, month = {Sep}, pages = {6739-6751}, type = {Article}, abstract = {The photochemical conversion of a series of alpha-mesitylacetophenone derivatives into 2-indanols via delta-hydrogen abstraction has been investigated in the solid state. A correlation between solid-state reactivity and crystal structure has been established for this type of reaction. For the seven compounds whose crystal structures were determined, the average value of d (C=O...H distance) and L (C=O...CH3 distance) were 2.77+/-0.04 Angstrom and 3.42+/-0.06 Angstrom, and the value of omega (delta-H out of plane angle), d (C=O...H angle) and a (C-H...O angle) were 59+/-2 degrees, 80+/-7 degrees and 123+/-3 degrees, respectively. These parameters depended mainly on the magnitude of the deviation of the carbonyl group from the fully bisecting position over the mesityl ring, which ranged from 9-14 degrees in the case of in the solid state reactive ketones and approached 0 degrees for the unreactive compounds. Asymmetric induction studies were carried out by providing the reactants with carboxylic acid substituents to which ionic chiral auxiliaries were attached through salt formation with optically active amines. Irradiation of the salts (13 in total) in the crystalline state gave enantiomeric excesses of up to 90\%. The crystal structures of three of the salts were determined and on this basis, the reasons for the selectivity in the crystalline state are discussed. (C) 2000 Elsevier Science Ltd. All rights reserved.}, keywords = {ABSTRACTION, ASYMMETRIC INDUCTION, CARBOXYLATE SALTS, CYCLIZATION, PHOTOCHEMISTRY, TRIPLETS, YANG PHOTOCYCLIZATION REACTION}, isbn = {0040-4020}, url = {://000089149100018}, author = {Cheung, E. and Rademacher, K. and Scheffer, J. R. and Trotter, J.} } @article {4766, title = {An investigation of the solid-state photochemistry of alpha-mesitylacetophenone derivatives: Asymmetric induction studies and crystal structure-reactivity relationships}, journal = {Tetrahedron}, volume = {56}, number = {36}, year = {2000}, note = {ISI Document Delivery No.: 351GHTimes Cited: 10Cited Reference Count: 24}, month = {Sep}, pages = {6739-6751}, type = {Article}, abstract = {The photochemical conversion of a series of alpha-mesitylacetophenone derivatives into 2-indanols via delta-hydrogen abstraction has been investigated in the solid state. A correlation between solid-state reactivity and crystal structure has been established for this type of reaction. For the seven compounds whose crystal structures were determined, the average value of d (C=O...H distance) and L (C=O...CH3 distance) were 2.77+/-0.04 Angstrom and 3.42+/-0.06 Angstrom, and the value of omega (delta-H out of plane angle), d (C=O...H angle) and a (C-H...O angle) were 59+/-2 degrees, 80+/-7 degrees and 123+/-3 degrees, respectively. These parameters depended mainly on the magnitude of the deviation of the carbonyl group from the fully bisecting position over the mesityl ring, which ranged from 9-14 degrees in the case of in the solid state reactive ketones and approached 0 degrees for the unreactive compounds. Asymmetric induction studies were carried out by providing the reactants with carboxylic acid substituents to which ionic chiral auxiliaries were attached through salt formation with optically active amines. Irradiation of the salts (13 in total) in the crystalline state gave enantiomeric excesses of up to 90\%. The crystal structures of three of the salts were determined and on this basis, the reasons for the selectivity in the crystalline state are discussed. (C) 2000 Elsevier Science Ltd. All rights reserved.}, keywords = {ABSTRACTION, ASYMMETRIC INDUCTION, CARBOXYLATE SALTS, CYCLIZATION, PHOTOCHEMISTRY, TRIPLETS, YANG PHOTOCYCLIZATION REACTION}, isbn = {0040-4020}, url = {://000089149100018}, author = {Cheung, E. and Rademacher, K. and Scheffer, J. R. and Trotter, J.} } @article {4546, title = {Synthesis and structure of the tantalum trimethyl complex [P2N2]TaMe3 and its conversion to the tantalum methylidene species [P2N2]Ta = CH2(Me) ([P2N2] = PhP(CH2SiMe2NSiMe2CH2)(2)PPh)}, journal = {Organometallics}, volume = {18}, number = {20}, year = {1999}, note = {ISI Document Delivery No.: 244CDTimes Cited: 25Cited Reference Count: 42}, month = {Sep}, pages = {4059-4067}, type = {Article}, abstract = {A tantalum(V) trimethyl complex and its photolysis product, a relatively stable tantalum(V) methyl methylidene, were prepared using the macrocyclic bis(amido-phosphine) PhP(CH2SiMe2NSiMe2CH2)(2)PPh, abbreviated [P2N2], as an ancillary ligand. The methylidene precursor [P2N2]TaMe3 is generated by the reaction of [P2N2]Li-2. C4H8O2 (C4H8O2 = 1,4-dioxane) with TaMe3Cl2. The solid-state X-ray molecular structure demonstrates that the geometry of [P2N2]TaMe3 is a seven-coordinate capped trigonal prism, and NMR studies confirm this is also true in solution at low temperature. Photolysis with a UV source generates [P2N2]Ta=CH2(Me), with the elimination of methane. The X-ray solid-state molecular structure of [P2N2]Ta=CH2(Me) is intermediate between octahedral and trigonal-prismatic geometry. Variable-temperature NMR studies demonstrate that the double-bonded methylidene moiety rotates with a barrier of 33.5 +/- 0.6 kJ/mol, in contrast to the larger barrier estimated for the previously characterized 18-electron complex (eta(5)-C5H5)(2)Ta=CH2(Me). Reaction of [P2N2]TaMe3 with Ph3C+BF4- or PhNMe2H+B(C6F5)(4)(-) produced {[P2N2]TaMe2}+BF4- and {[P2N2]TaMe2}B+(C6F5)(4)(-), respectively. Attempts to deprotonate {[P2N2]TaMe2}(+) did not provide a chemical route to [P2N2]Ta=CH2(Me) and instead generated either [P2N2]TaMe2F or the product of deprotonation of the [P2N2] ligand methylene backbone, Ta(Me-2)[(CHSiMe2NSiMe2CH2P(Ph)CH2SiMe2NSiMe2CH2PPh)], depending on the base and counteranion used.}, keywords = {ABSTRACTION, CATALYSIS, COORDINATION, CRYSTAL-STRUCTURES, DECOMPOSITION, DERIVATIVES, imido, METAL-CARBON BONDS, METHYLENE COMPLEX, REACTIVITY}, isbn = {0276-7333}, url = {://000083033500019}, author = {Fryzuk,Michael D. and Johnson, S. A. and Rettig, S. J.} } @article {4189, title = {Synthesis and characterization of homoleptic ruthenium(II) imidazole complexes, and a carbonyl species derived by CO abstraction from DMF}, journal = {Canadian Journal of Chemistry-Revue Canadienne De Chimie}, volume = {76}, number = {10}, year = {1998}, note = {ISI Document Delivery No.: 156LMTimes Cited: 15Cited Reference Count: 37}, month = {Oct}, pages = {1379-1388}, type = {Article}, abstract = {{[Ru(II)(L)(6)](2+) complexes were synthesized from [Ru(DMF)(6)][CF3SO3](3); DMF = dimethylformamide}, keywords = {ABSTRACTION, AQUATION, CHEMISTRY, CO, COORDINATION, crystal structures, CRYSTAL-STRUCTURES, hexakis(imidazole)ruthenium(II) triflates, PORPHYRIN}, isbn = {0008-4042}, url = {://000078002800008}, author = {Baird, I. R. and Rettig, S. J. and James, Brian R. and Skov, K. A.} } @article {4143, title = {Thermal alkane C-H bond activation by a tungsten alkylidene complex: The reversal of alpha-hydrogen elimination}, journal = {Journal of the American Chemical Society}, volume = {119}, number = {21}, year = {1997}, note = {ISI Document Delivery No.: XB674Times Cited: 52Cited Reference Count: 36}, month = {May}, pages = {5071-5072}, type = {Article}, keywords = {ABSTRACTION, ADDUCTS, ARYL, BINDING, CHEMISTRY, DERIVATIVES, LIGANDS, METAL-COMPLEXES, REACTIVITY, tantalum}, isbn = {0002-7863}, url = {://A1997XB67400046}, author = {Tran, E. and Legzdins,Peter} } @article {3742, title = {On the conformational analysis and photochemical reactivity of 1,6-cyclodecanedione}, journal = {Molecular Crystals and Liquid Crystals Science and Technology Section a-Molecular Crystals and Liquid Crystals}, volume = {276}, year = {1996}, note = {ISI Document Delivery No.: UJ432Times Cited: 0Cited Reference Count: 2712th International Conference on the Chemistry of the Organic Solid State (ICCOSS XII)JUL 09-14, 1995MATSUYAMA, JAPANMinist Educ, Japan, Ehime Univ, Chem Soc Japan, Soc Synthet Organ Chem, Japan}, pages = {A289-A298}, type = {Proceedings Paper}, abstract = {Photolysis of 1,5-cyclodecanedione, both in the crystalline state and in solution, fails to lead to any Norrish/Yang type II products despite the fact that the conformation of the molecule in the solid state is nearly ideal for hydrogen atom abstraction. Based on X-ray crystal structure and molecular modeling studies, it is argued that gamma-hydrogen abstraction does occur in the solid state, but that closure of the resulting 1,4-biradical is slower than reverse hydrogen atom transfer owing to difficulty in forming the expected 8-membered ring-containing photoproduct. In solution, on the other hand, molecular mechanics calculations indicate that the lack of photoreactivity of 1,5-cyclodecanedione stems from the fact that this molecule exists nearly exclusively in a conformation for which gamma-hydrogen abstraction is sterically impossible.}, keywords = {ABSTRACTION, C-H...O, II REACTIONS, KETONES, MOLECULAR MECHANICS METHODOLOGY}, isbn = {1058-725X}, url = {://A1996UJ43200083}, author = {Lewis, T. J. and Rettig, S. J. and Sauers, R. R. and Scheffer, J. R. and Trotter, J. and Wu, C. H.} } @article {3742, title = {On the conformational analysis and photochemical reactivity of 1,6-cyclodecanedione}, journal = {Molecular Crystals and Liquid Crystals Science and Technology Section a-Molecular Crystals and Liquid Crystals}, volume = {276}, year = {1996}, note = {ISI Document Delivery No.: UJ432Times Cited: 0Cited Reference Count: 2712th International Conference on the Chemistry of the Organic Solid State (ICCOSS XII)JUL 09-14, 1995MATSUYAMA, JAPANMinist Educ, Japan, Ehime Univ, Chem Soc Japan, Soc Synthet Organ Chem, Japan}, pages = {A289-A298}, type = {Proceedings Paper}, abstract = {Photolysis of 1,5-cyclodecanedione, both in the crystalline state and in solution, fails to lead to any Norrish/Yang type II products despite the fact that the conformation of the molecule in the solid state is nearly ideal for hydrogen atom abstraction. Based on X-ray crystal structure and molecular modeling studies, it is argued that gamma-hydrogen abstraction does occur in the solid state, but that closure of the resulting 1,4-biradical is slower than reverse hydrogen atom transfer owing to difficulty in forming the expected 8-membered ring-containing photoproduct. In solution, on the other hand, molecular mechanics calculations indicate that the lack of photoreactivity of 1,5-cyclodecanedione stems from the fact that this molecule exists nearly exclusively in a conformation for which gamma-hydrogen abstraction is sterically impossible.}, keywords = {ABSTRACTION, C-H...O, II REACTIONS, KETONES, MOLECULAR MECHANICS METHODOLOGY}, isbn = {1058-725X}, url = {://A1996UJ43200083}, author = {Lewis, T. J. and Rettig, S. J. and Sauers, R. R. and Scheffer, J. R. and Trotter, J. and Wu, C. H.} } @article {3330, title = {THE NOVEL PHOTOCHEMICAL BEHAVIOR OF TRIPTYCENE-1,4-QUINONE}, journal = {Tetrahedron Letters}, volume = {36}, number = {12}, year = {1995}, note = {ISI Document Delivery No.: QP020Times Cited: 8Cited Reference Count: 10}, month = {Mar}, pages = {2025-2028}, type = {Article}, abstract = {Triptycene-1,4-quinone (1) reacts photochemically in solution to give different products depending on the solvent employed and on the presence or absence of oxygen. The structures of the photoproducts have been elucidated by spectroscopic methods, independent synthesis and single crystal X-ray diffractometry, and possible mechanistic pathways leading to their formation are presented and discussed. Unexpectedly, quinone 1 was found to be photochemically inert in the crystalline state. The X-ray crystal structure of 1 reveals the probable reason for this behavior.}, keywords = {10-DIHYDRO-9, 10-ORTHO-BENZENOANTHRACENE-1, 4-DIONES, 9, ABSTRACTION, DERIVATIVES, INTRAMOLECULAR CHARGE-TRANSFER, TRANSITION}, isbn = {0040-4039}, url = {://A1995QP02000014}, author = {Fu, T. Y. and Gamlin, J. N. and Olovsson, G. and Scheffer, J. R. and Trotter, J. and Young, D. T.} } @article {3330, title = {THE NOVEL PHOTOCHEMICAL BEHAVIOR OF TRIPTYCENE-1,4-QUINONE}, journal = {Tetrahedron Letters}, volume = {36}, number = {12}, year = {1995}, note = {ISI Document Delivery No.: QP020Times Cited: 8Cited Reference Count: 10}, month = {Mar}, pages = {2025-2028}, type = {Article}, abstract = {Triptycene-1,4-quinone (1) reacts photochemically in solution to give different products depending on the solvent employed and on the presence or absence of oxygen. The structures of the photoproducts have been elucidated by spectroscopic methods, independent synthesis and single crystal X-ray diffractometry, and possible mechanistic pathways leading to their formation are presented and discussed. Unexpectedly, quinone 1 was found to be photochemically inert in the crystalline state. The X-ray crystal structure of 1 reveals the probable reason for this behavior.}, keywords = {10-DIHYDRO-9, 10-ORTHO-BENZENOANTHRACENE-1, 4-DIONES, 9, ABSTRACTION, DERIVATIVES, INTRAMOLECULAR CHARGE-TRANSFER, TRANSITION}, isbn = {0040-4039}, url = {://A1995QP02000014}, author = {Fu, T. Y. and Gamlin, J. N. and Olovsson, G. and Scheffer, J. R. and Trotter, J. and Young, D. T.} } @article {3528, title = {THE THERMAL-REACTION RATE OF MUONIUM WITH METHANE (AND ETHANE) IN THE GAS-PHASE}, journal = {Journal of Chemical Physics}, volume = {102}, number = {12}, year = {1995}, note = {ISI Document Delivery No.: QM507Times Cited: 12Cited Reference Count: 52}, month = {Mar}, pages = {4860-4869}, type = {Article}, keywords = {ABINITIO, ABSTRACTION, DYNAMICS, FLASH-PHOTOLYSIS, H-2 REVERSIBLE CH4+H, MU+D2, RATE CONSTANTS, REACTION-KINETICS, SURFACES, TRANSITION-STATE THEORY}, isbn = {0021-9606}, url = {://A1995QM50700015}, author = {Snooks, R. and Arseneau, D. J. and Fleming, Donald G. and Senba, M. and Pan, J. J. and Shelley, M. and Baer, S.} } @article {3036, title = {A NEW MECHANISM FOR THE PHOTOCLEAVAGE OF MONOTHIOIMIDES}, journal = {Tetrahedron Letters}, volume = {35}, number = {20}, year = {1994}, note = {ISI Document Delivery No.: NM584Times Cited: 5Cited Reference Count: 8}, month = {May}, pages = {3235-3238}, type = {Article}, abstract = {Based on solid state structure-reactivity correlation studies and on deuterium labeling experiments, it is concluded that the photochemical formation of thiobenzanilides 2a-d from monothioimides 1a-d does not involve initial gamma-hydrogen atom abstraction as originally suggested in the literature. Alternative mechanistic possibilities are presented and discussed.}, keywords = {ABSTRACTION}, isbn = {0040-4039}, url = {://A1994NM58400005}, author = {Fu, T. Y. and Scheffer, J. R. and Trotter, J.} } @article {3036, title = {A NEW MECHANISM FOR THE PHOTOCLEAVAGE OF MONOTHIOIMIDES}, journal = {Tetrahedron Letters}, volume = {35}, number = {20}, year = {1994}, note = {ISI Document Delivery No.: NM584Times Cited: 5Cited Reference Count: 8}, month = {May}, pages = {3235-3238}, type = {Article}, abstract = {Based on solid state structure-reactivity correlation studies and on deuterium labeling experiments, it is concluded that the photochemical formation of thiobenzanilides 2a-d from monothioimides 1a-d does not involve initial gamma-hydrogen atom abstraction as originally suggested in the literature. Alternative mechanistic possibilities are presented and discussed.}, keywords = {ABSTRACTION}, isbn = {0040-4039}, url = {://A1994NM58400005}, author = {Fu, T. Y. and Scheffer, J. R. and Trotter, J.} } @article {7303, title = {ORGANOMETALLIC NITROSYL CHEM .52. A UNIQUE MU-ETA-1-ETA-2-NO LIGAND IN A BIMETALLIC ALKYLIDENE NITROSYL COMPLEX OF MOLYBDENUM}, journal = {Journal of the American Chemical Society}, volume = {114}, number = {17}, year = {1992}, note = {ISI Document Delivery No.: JH996Times Cited: 15Cited Reference Count: 18}, month = {Aug}, pages = {6922-6923}, type = {Note}, keywords = {ABSTRACTION, CHEMISTRY, COMPOUND, DOUBLE-BOND, MOLECULAR-STRUCTURE, REACTIVITY, TETRANITROSYL, TUNGSTEN}, isbn = {0002-7863}, url = {://A1992JH99600051}, author = {Legzdins,Peter and Rettig, S. J. and Veltheer, J. E.} }