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225 results on '"McDouall, Joseph J. W."'

8. Copper‐Catalyzed Borylative Cross‐Coupling of Allenes and Imines: Selective Three‐Component Assembly of Branched Homoallyl Amines

Author

Rae, James, Yeung, Kay, McDouall, Joseph J. W., and Procter, David J.

Subjects
allenes, Communication, copper, imines, cross-coupling, Copper Catalysis, boron, Communications
Abstract

A copper‐catalyzed three‐component coupling of allenes, bis(pinacolato)diboron, and imines allows regio‐, chemo‐, and diastereoselective assembly of branched α,β‐substituted‐γ‐boryl homoallylic amines, that is, products bearing versatile amino, alkenyl, and borane functionality. Alternatively, convenient oxidative workup allows access to α‐substituted‐β‐amino ketones. A computational study has been used to probe the stereochemical course of the cross‐coupling.

Published
2015

10. C−H Borylation/Cross-Coupling Forms Twisted Donor-Acceptor Compounds Exhibiting Donor-Dependent Delayed Emission

Author

Crossley, Daniel L., primary, Kulapichitr, Pakapol, additional, Radcliffe, James E., additional, Dunsford, Jay J., additional, Vitorica-Yrezabal, Inigo, additional, Kahan, Rachel J., additional, Woodward, Adam W., additional, Turner, Michael L., additional, McDouall, Joseph J. W., additional, and Ingleson, Michael J., additional

Published
2018
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12. An Approach to the Synthesis of Functionalized Polycyclic Aromatic Hydrocarbons

Author

Little, Mark, Lan, He, Raftery, James, Morrison, John J, McDouall, Joseph J W, Yeates, Stephen G, and Quayle, Peter

Subjects
Polycycles, Cyclization, Short Communications, Benzannulation, Radicals, Hydrocarbons
Abstract

The application of a new benzannulation reaction for the regiocontrolled synthesis of functionalized chrysenes is reported. The initial benzannulation and the subsequent halogen displacement reactions are both highly regiospecific, which thereby enables the regiocontrolled synthesis of a variety of 4,10-disubstituted chrysenes from commercially available 1,5-dihydroxynaphthalene.

Published
2013

14. Nickel(II) and palladium(II) complexes of azobenzene-containing ligands as dichroic dyes

Author

Blackburn, Octavia A., Coe, Benjamin J., Fielden, John, Helliwell, Madeleine, McDouall, Joseph J. W., and Hutchings, Michael G.

Subjects
Benzene -- Structure, Benzene -- Chemical properties, Density functionals -- Usage, Circular dichroism -- Usage, Nickel -- Chemical properties, Nuclear magnetic resonance spectroscopy -- Usage, Organometallic compounds -- Structure, Organometallic compounds -- Chemical properties, Organometallic compounds -- Optical properties, Palladium -- Chemical properties, Chemistry
Published
2010

16. Binding CO2 by a Cr8 Metallacrown

Author

Vitórica-Yrezábal, Iñigo J., primary, Sava, Daniel Florin, additional, Timco, Grigore A., additional, Brown, Martyn S., additional, Savage, Mathew, additional, Godfrey, Harry G. W., additional, Moreau, Florian, additional, Schröder, Martin, additional, Siperstein, Flor, additional, Brammer, Lee, additional, Yang, Sihai, additional, Attfield, Martin P., additional, McDouall, Joseph J. W., additional, and Winpenny, Richard E. P., additional

Published
2017
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18. Modelling the Effect of Zero-Field Splitting on the ¹H, 13C and 29Si Chemical Shifts of Lanthanide and Actinide Compounds.

Author

Lloyd, Austin W., Moylan, Helen M., and McDouall, Joseph J. W.

Subjects
CHEMICAL shift (Nuclear magnetic resonance), RARE earth metals, ACTINIUM compounds, QUANTUM chemistry, SPINTRONICS
Abstract

The prediction of paramagnetic NMR (pNMR) chemical shifts in molecules containing heavy atoms presents a significant challenge to computational quantum chemistry. The importance of meeting this challenge lies in the central role that NMR plays in the structural characterisation of chemical systems. Hence there is a need for reliable assignment and prediction of chemical shifts. In a previous study [Trends in Physical Chemistry, 17, 25-57, (2017)] we looked at the computation of pNMR chemical shifts in lanthanide and actinide complexes using a spin Hamiltonian approach. In that study we were principally concerned with molecules with S = 1/2 ground states. In the present work we extend that study by looking at the effect of zero field splitting (ZFS) for six complexes with S = 3/2 ground states. It is shown that the inclusion of ZFS can produce substantial shifts in the predicted chemical shifts. The computations presented are typically sufficient to enable assignment of experimental spectra. However for one case, in which the peaks are closely clustered, the inclusion of ZFS re-orders the chemical shifts making assignment quite difficult. We also observe, and echo, the previously reported importance of including the paramagnetic spin-orbit hyperfine interaction for 13C and 29Si atoms, when these are directly bound to a heavy element and thus subject to heavy-atom-light-atom effects. The necessary computations are very demanding, and more work is needed to find theoretical and computational approaches that simplify the evaluation of this term. We discuss the computation of each term required in the spin Hamiltonian. The systems we study in this work are restricted to a single heavy atom ion (one Nd(III) and five U(III) complexes), but typify some of the computational complexity encountered in lanthanide and actinide containing molecules. [ABSTRACT FROM AUTHOR]

Published
2019
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19. Parametrization of a Heitler–London valence bond Hamiltonian from complete-active-space self-consistent-field computations: An application to chemical reactivity.

Author

Bernardi, Fernando, Olivucci, Massimo, McDouall, Joseph J. W., and Robb, Michael A.

Subjects
SELF-consistent field theory, WAVE functions, HAMILTONIAN systems, MOLECULAR structure, RING formation (Chemistry)
Abstract

A simple practical procedure is proposed for the transformation of a complete-active-space self-consistent-field (CAS-SCF) wave function to Heitler–London valence bond space via the construction of an effective (Heisenberg) Hamiltonian. With such a procedure, the computed Heitler–London parameters [ATOTHER]@sQ[/ATOTHER]and [ATOTHER]@sK[/ATOTHER]ijcan be used for a posteriori rationalization of the bonding effects in molecular structures. In particular, the diabatization of the adiabatic potential surface, first proposed by Evans can now be accomplished in a rigorous way. The technique is applied to some previously computed transition structures for cycloaddition reactions. [ABSTRACT FROM AUTHOR]

Published
1988
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20. Dihydrothiophenes containing quaternary stereogenic centres by sequential stereospecific rearrangements and ring-closing metathesis

Author

Mingat, Gaëlle, McDouall, Joseph J W, and Clayden, Jonathan

Abstract

Stereospecific [3,3]-sigmatropic rearrangement of O-substituted thiocarbamate derivatives of enantiopure allylic alcohols provides allylic thiocarbamates as single enantiomers. Intramolecular arylation by rearrangement of their allyllithium derivatives provides allylic tertiary thiols. Allylation and ring-closing metathesis gives 2,5-dihydrothiophenes containing sulfur-bearing quaternary centres.

Published
2014
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25. Controlling the conformational changes in donor-acceptor [4]-dendralenes through intramolecular charge-transfer processes

Author

Kanibolotsky, Alexander L., Forgie, John C., McEntee, Greg J., Talpur, M. Munsif A., Skabara, Peter J., Westgate, Thomas D. J., McDouall, Joseph J. W., Auinger, Michael, Coles, Simon J., and Hursthouse, Michael B.

Abstract

The synthesis of two [4]-dendralene compounds incorporating thiophene-(p-nitrophenyl) donor-acceptor units is presented. The dendralenes adopt two different conformers in solution and solid state and the transformation between the structures can be controlled by light and heat. The electron-donating components of the dendralenes are represented by bromothienyl (in 13) and ethylenedioxythiophene(EDOT)-thienyl (in 15) end-groups. The most facile transformation involves the isomerisation of donor-acceptor conjugated systems (a conformers) into structures in which only the thiophenes are conjugated (b conformers), and this process is driven by ambient light. The structures of the two conformers of compound 13 are confirmed by single-crystal X-ray diffraction studies and the structural changes in both compounds have been monitored by 1H NMR spectroscopy and absorption studies. The transformations were found to be first-order processes with rate constants of k=0.0027 s(-1) and k=0.00022 s(-1) for 13 and 15, respectively. Density functional theory calculations at the B3LYP/6-31G* level give credence to the proposed mechanism for the a-->b conversion, which involves photoinduced intramolecular charge transfer (ICT) as the key step. The EDOT derivative (15) can be polymerised by electrochemical oxidation and a combination of cyclic voltammetry and UV/Vis spectroelectrochemical experiments indicate that the a conformer can be trapped and stabilised in the solid state.

Published
2009

26. Electronic g Tensors in UV Complexes-A Computational Study.

Author

Moylan, Helen M. and McDouall, Joseph J W.

Subjects
*TRANSITION metals, *METAL complexes, *QUANTUM chemistry, *ACTINIDE elements, *ELECTRONIC structure
Abstract

The theory and computation of EPR parameters from first principles has seen a great deal of development over the past two decades. In particular, various techniques for the computation of the electronic g tensor have been implemented in many quantum chemistry packages. These methods have been successfully applied to paramagnetic organic species and transition metal systems. The situation is less well-understood and established in the case of actinide-containing molecules and there is a dearth of experimental data available for validation of computations. In this study quantum chemical techniques have been used to evaluate the g tensor for UV complexes, for which experimental data are available for comparison. The g tensors were calculated using relatively simple, state-averaged complete active space self-consistent field (SA-CASSCF) calculations. This approach is shown to be capable of providing useful accuracy. Aspects of the computations that should be refined to provide a more quantitative approach are discussed. The key features of the underlying electronic structure that influence the computed g values are delineated, providing a simple physical picture of these subtle molecular properties. [ABSTRACT FROM AUTHOR]

Published
2017
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27. Binding CO2 by a Cr8 Metallacrown.

Author

Vitórica ‐ Yrezábal, Iñigo J., Sava, Daniel Florin, Timco, Grigore A., Brown, Martyn S., Savage, Mathew, Godfrey, Harry G. W., Moreau, Florian, Schröder, Martin, Siperstein, Flor, Brammer, Lee, Yang, Sihai, Attfield, Martin P., McDouall, Joseph J. W., and Winpenny, Richard E. P.

Subjects
METALLACROWNS, ABSORPTION, BINDING agents, CRYSTALS, X-ray diffraction
Abstract

The {Cr8} metallacrown [CrF(O2CtBu)2]8, containing a F-lined internal cavity, shows high selectivity for CO2 over N2. DFT calculations and absorption studies support the multiple binding of F-groups to the C-center of CO2 (C⋅⋅⋅F 3.190(9)-3.389(9) Å), as confirmed by single-crystal X-ray diffraction. [ABSTRACT FROM AUTHOR]

Published
2017
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33. Synthesis, spectroscopy and electronic structure of the vinylidene and alkynyl complexes [W(C=CHR)(dppe)(η-C7H7)]+ and [W(C≡CR)(dppe)(η-C7H7)]n+ (n = 0 or 1)

Author

Lancashire, Hannah N., Brown, Neil J., Carthy, Laura, Collison, David, Fitzgerald, Emma C., Edge, Ruth, Helliwell, Madeleine, Holden, Mark, Low, Paul J., McDouall, Joseph J. W., Whiteley, Mark W., Lancashire, Hannah N., Brown, Neil J., Carthy, Laura, Collison, David, Fitzgerald, Emma C., Edge, Ruth, Helliwell, Madeleine, Holden, Mark, Low, Paul J., McDouall, Joseph J. W., and Whiteley, Mark W.

Abstract

The first examples of vinylidene complexes of the cycloheptatrienyl tungsten system [W(C=CHR)(dppe)(η-C7H7)]+ (dppe = Ph2PCH2CH2PPh2; R = H, 3; Ph, 4; C6H4-4-Me, 5) have been synthesised by reaction of [WBr(dppe)(η-C7H7)], 1, with terminal alkynes HC[triple bond, length as m-dash]CR; a one-pot synthesis of 1 from [WBr(CO)2(η-C7H7)] facilitates its use as a precursor. The X-ray structure of 4[PF6] reveals that the vinylidene ligand substituents lie in the pseudo mirror plane of the W(dppe)(η-C7H7) auxiliary (vertical orientation) with the phenyl group located syn to the cycloheptatrienyl ring. Variable temperature 1H NMR investigations on [W(C[double bond, length as m-dash]CH2)(dppe)(η-C7H7)][PF6], 3, estimate the energy barrier to rotation about the W[double bond, length as m-dash]Cα bond as 62.5 ± 2 kJ mol−1; approximately 10 kJ mol−1 greater than for the molybdenum analogue. Deprotonation of 4 and 5 with KOBut yields the alkynyls [W(C≡CR)(dppe)(η-C7H7)] (R = Ph, 6; C6H4-4-Me, 7) which undergo a reversible one-electron oxidation at a glassy carbon electrode in CH2Cl2 with E½ values approximately 0.12 V negative of Mo analogues. The 17-electron radicals [6]+ and [7]+ have been investigated by spectroelectrochemical IR, UV-visible and EPR methods. The electronic structures of representative vinylidene (3) and alkynyl (6) complexes have been investigated at the B3LYP/Def2-SVP level. In both cases, electronic structure is characterised by a frontier orbital with significant metal dz2character and this dominates the structural and spectroscopic properties of the system.

Published
2011

34. Modification of the magnetic properties of a heterometallic wheel by inclusion of a Jahn-Teller distorted Cu(II) ion

Author

Baker, Michael L., Piligkos, Stergios, Bianchi, Alberto, Carretta, Stefano, Collison, David, McDouall, Joseph J. W., McInnes, Eric J. L., Mutka, Hannu, Timco, Grigore A., Tuna, Floriana, Vadivelu, Prabha, Weihe, Høgni, Güdel, Hans U., Winpenny, Richard E. P., Baker, Michael L., Piligkos, Stergios, Bianchi, Alberto, Carretta, Stefano, Collison, David, McDouall, Joseph J. W., McInnes, Eric J. L., Mutka, Hannu, Timco, Grigore A., Tuna, Floriana, Vadivelu, Prabha, Weihe, Høgni, Güdel, Hans U., and Winpenny, Richard E. P.

Published
2011

35. Copper-Catalyzed Borylative Cross-Coupling of Alienes and Imines: Selective Three-Component Assembly of Branched Homoallyl Amines.

Author

Rae, James, Yeung, Kay, McDouall, Joseph J. W., and Procter, David J.

Subjects
COPPER catalysts, COUPLING reactions (Chemistry), MOLECULAR self-assembly, AMINE analysis, IMINES, STEREOSELECTIVE reactions
Abstract

A copper-catalyzed three-component coupling of allenes, bis(pinacolato)diboron, and imines allows regio-, chemo-, and diastereoselective assembly of branched α,βsubstituted- g-boryl homoallylic amines, that is, products bearing versatile amino, alkenyl, and borane functionality. Alternatively, convenient oxidative workup allows access to α-substituted- β-amino ketones. A computational study has been used to probe the stereochemical course of the cross-coupling. [ABSTRACT FROM AUTHOR]

Published
2016
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37. Origin of Impurities Formed in the Polyurethane Production Chain. 1. Conditions for Chlorine Transfer from an Aryl Isocyanide Dichloride Byproduct

Author

Callison, June, primary, Edge, Ruth, additional, de Cuba, Kimberly R., additional, Carr, Robert H., additional, McDouall, Joseph J. W., additional, Collison, David, additional, McInnes, Eric J. L., additional, van der Borden, Willem, additional, van der Velde, Klaas, additional, Winfield, John M., additional, and Lennon, David, additional

Published
2012
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39. Modification of the magnetic properties of a heterometallic wheel by inclusion of a Jahn–Teller distorted Cu(ii) ion

Author

Baker, Michael L., primary, Piligkos, Stergios, additional, Bianchi, Alberto, additional, Carretta, Stefano, additional, Collison, David, additional, McDouall, Joseph J. W., additional, McInnes, Eric J. L., additional, Mutka, Hannu, additional, Timco, Grigore A., additional, Tuna, Floriana, additional, Vadivelu, Prabha, additional, Weihe, Høgni, additional, Güdel, Hans U., additional, and Winpenny, Richard E. P., additional

Published
2011
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40. Synthesis, spectroscopy and electronic structure of the vinylidene and alkynyl complexes [W(CCHR)(dppe)(η-C7H7)]+and [W(CCR)(dppe)(η-C7H7)]n+(n = 0 or 1)

Author

Lancashire, Hannah N., primary, Brown, Neil J., additional, Carthy, Laura, additional, Collison, David, additional, Fitzgerald, Emma C., additional, Edge, Ruth, additional, Helliwell, Madeleine, additional, Holden, Mark, additional, Low, Paul J., additional, McDouall, Joseph J. W., additional, and Whiteley, Mark W., additional

Published
2011
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45. Spectroscopic Properties and Electronic Structure of the Cycloheptatrienyl Molybdenum Alkynyl Complexes [Mo(C≡CR)(Ph2PCH2CH2PPh2)(η-C7H7)]n+(n= 0 or 1; R =But, Fc, CO2Me, or C6H4-4-X, X = NH2, OMe, Me, H, CHO, CO2Me)

Author

Brown, Neil J., primary, Collison, David, additional, Edge, Ruth, additional, Fitzgerald, Emma C., additional, Helliwell, Madeleine, additional, Howard, Judith A. K., additional, Lancashire, Hannah N., additional, Low, Paul J., additional, McDouall, Joseph J. W., additional, Raftery, James, additional, Smith, Charlene A., additional, Yufit, Dmitry S., additional, and Whiteley, Mark W., additional

Published
2010
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47. Experimental observation of spin delocalisation onto the aryl-alkynyl ligand in the complexes [Mo(CCAr)(Ph2PCH2CH2PPh2)(η-C7H7)]+ (Ar = C6H5, C6H4-4-F; C7H7 = cycloheptatrienyl): an EPR and ENDOR investigation

Author

Carter, Emma, primary, Collison, David, additional, Edge, Ruth, additional, Fitzgerald, Emma C., additional, Lancashire, Hannah N., additional, Murphy, Damien M., additional, McDouall, Joseph J. W., additional, Sharples, Joseph, additional, and Whiteley, Mark W., additional

Published
2010
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49. Metallacumulenylidene Complexes in the Cycloheptatrienyl Molybdenum Series [Mo{(C)n═CR2}L2(η-C7H7)]+ (n = 0−2; L2 = P-Donor Ligand). X-ray Crystal Structures of [Mo{C═C(H)Ph}{P(OMe)3}2(η-C7H7)][BF4] and [Mo(C═C═CPh2)(dppe)(η-C7H7)][PF6] and DFT Investigation of Cumulenylidene Ligand Orientations

Author

Grime, Richard W., primary, Helliwell, Madeleine, additional, Hussain, Zaffar I., additional, Lancashire, Hannah N., additional, Mason, Christopher R., additional, McDouall, Joseph J. W., additional, Mydlowski, Christopher M., additional, and Whiteley, Mark W., additional

Published
2008
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