142 results for The University of Auckland Library, Boyd, Peter

  • The Mechanism of Action of Di-heme Peroxidases: A Theoretical Study

    Brittain, Tom; Boyd, Peter; Fulop, V; Echalier, A (2008)

    Book item
    The University of Auckland Library

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  • Supramolecular Assembly of Photoactive Porphyrin-Fullerene Dyads and Triads

    Boyd, Peter (2008)

    Conference item
    The University of Auckland Library

    The supramolecular attraction of fullerenes, such as C60 and C70, to porphyrins has been used as a recognition element in the formation of donor (porphyrin)-acceptor (fullerene) complexes in the solid state and in molecular bis-porphyrin hosts. 1 In this paper we present recent studies of the roles of linker, porphyrin substituent, metallation and solvent on the magnitude of fullerene binding constants in bis-porphyrin hosts(1). 2 These hostguest complexes can exhibit photoinduced electron transfer, PET, (porphyrin to C60) upon photoexcitation, which is of interest in the construction of photovoltaic devices.

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  • Molten salt mixtures. XI. Integral and partial molar volumes in the molten salt systems PbCl2 + NaCl, PbCl2 + RbCl, PbCl2 + CsCl, CdCl2 + RbCl, and CdCl2 + CsCl

    Bloom, H; Boyd, Peter; Laver, JL; Wong, J (1966)

    Journal article
    The University of Auckland Library

    The densities of molten PbCl2, CsCl, and RbCl and of the molten salt systems PbCl2 + NaCl, PbCl2 + RbCl, PbCl2 + CsCl, CdCl2 + RbCl, and CdCl, + CsCl have been measured to an accuracy of ±0.1% by an Archimedean method over a considerable temperature range. Integral and partial molar volume isotherms have been constructed for the above binary systems and are interpreted to show that complex ions are formed in all but the PbCl2+NaCl system.

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  • New Bis-porphyrin Hosts for Fullerene Binding

    Boyd, Peter; jones, L; Lyons, D; Paauwe, JD; Robinson, I (2009)

    Conference item
    The University of Auckland Library

    Calix[4]arene linked bis porphyrin hosts, 1, have been designed as hosts for fullerenes. Association constants for fullerenes varies with porphyrin substituent, solvent and fullerene type. 1 The intrinsic strength of binding due to the porphyrin-fullerene interaction is enhanced by additional porphyrin C-H..fullerene interactions.

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  • Porphyrin-Fullerene Supramolecular Chemistry

    Boyd, Peter; Hosseini, A; van Paauwe, JD; Reed, CA (2011)

    Book item
    The University of Auckland Library

    This book covers the contributions of significant discoveries of fundamentals andapplications of fullerene and all-carbon nanomaterials from leading scientists ...

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  • 5,15-Bis(3,5-di-tert-butylphenyl)-3,7,13,17-tetramethyl-2,8,12,18-tetrapropylporphyrin

    Boyd, Peter; Chaker, L; Rickard, Clifton (2006)

    Journal article
    The University of Auckland Library

    The title molecule, C64H86N4 , possesses a crystallographically imposed centre of symmetry with a rectangular distortion of the porphyrin core. In the crystal structure, molecules form laddered assemblies via partial stacking of porphyrins. The assemblies are further formed into layers separated by tertbutyl groups.

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  • Crystal, molecular, and electronic structure of [Ta2Cl 4(??-Cl)4(PMe3)4]: A metal-metal single bond between eight-co-ordinate tantalum atoms

    Boyd, Peter; Jones, TC; Nielson, AJ; Rickard, CEF (1984)

    Journal article
    The University of Auckland Library

    The crystal structure of the title complex shows an MCl4M bridge across a weak Ta???Ta interaction and eight-fold co-ordination about each metal centre; an electronic structure calculation supports the existence of a ?? metal???metal bond.

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  • An SCF MS-X?? study of the bonding and nuclear quadrupole coupling in copper(I) and silver(I) halides

    Bowmaker, Graham; Boyd, Peter (1985)

    Journal article
    The University of Auckland Library

    SCF MS-X?? calculations of the electronic structure of diatomic copper(I) and silver(I) halides MX (M = Cu, Ag; X = F, Cl, Br, I) have been carried out to investigate the bonding and nuclear quadrupole coupling in these molecules. Reasonable agreement (to within 30%) is obtained between the calculated and observed halogen coupling constants. The agreement is rather poorer for the copper coupling constants, which are small in magnitude, since they result from near cancellation of large but opposing contributions from the copper 3d and 4p orbitals. However, the calculations reproduce the observed negative sign of the field gradient at the copper nucleus, as well as the observed decrease in the copper coupling constant from CuF to CuI. The reasons for this trend are discussed.

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  • ELECTRON-SPIN-RESONANCE STUDIES OF ONE-ELECTRON REDUCTION PRODUCTS OF NICKEL(II) AND PALLADIUM(II) COMPLEXES CONTAINING TETRATHIOMOLYBDATE, TETRATHIOTUNGSTATE, AND DIALKYLDITHIOCARBAMATE LIGANDS, "[M(M'S4)N(R2NCS2)2-N)]N-(N=0-2,M=NI OR PD,M'=MO OR W)

    Bowmaker, Graham; Boyd, Peter; CAMPBELL, GK; ZVAGULIS, M (1986-06-01)

    Journal article
    The University of Auckland Library

    The redox properties of nickel(II) and palladium(II) complexes of the type [M(M???S4)n(R2NCS2)2 ???n]n???(n= 0???2, M = Ni or Pd, M???= Mo or W) have been studied using d.c. and a.c. cyclic voltammetry at a platinum electrode in dichloromethane solution. The series of complexes show initial reversible or quasi-reversible one-electron reduction to give species containing a single unpaired electron. E.s.r. spectra have been used to identify the species produced after one-electron reduction. In the case of palladium, the reduction potential increases smoothly with increasing n whilst the unpaired electron is increasingly delocalised from the central metal ion with decreasing g anisotropy. In contrast, the reduction potential of the nickel complexes increases sharply from n= 0 to 1 with a corresponding increase in the g anisotropy. The reduction potential increases again for n= 2, however the e.s.r. spectrum shows an unusual ???reversal??? of g anisotropy (g??? < g???) compared to that expected for a d9 planar complex with the unpaired electron in a nickel dxy orbital (g??? > g???). It is suggested that in the case of n= 1 or 2 the unpaired electron is now occupying a molecular orbital composed of the low-lying molybdenum (or tungsten)d orbitals. This is supported by scattered wave X?? calculations of the electronic structure of the model complexes [Ni(H2NCS2)2], [Ni(MoS4)(H2NCS2)]??? and [Ni(MoS4)2]2??? and their oneelectron reduction products.

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  • Magnetic and structural studies on copper(II) dialkyldithiocarbamates

    Boyd, Peter; MITRA, S; RASTON, CL; ROWBOTTOM, GL; WHITE, AH (1981)

    Journal article
    The University of Auckland Library

    The magnetic susceptibilities of a series of copper(II) dialkyldithiocarbamates have been measured over the range 4???290 K, the alkyl groups being methyl, ethyl, isopropyl, and n-butyl. Contrary to a previous report of strong ferromagnetic interaction in the diethyl derivative, we find no evidence of any significant exchange interaction in this compound. The dimethyl and di-isopropyl analogues show weak antiferromagnetic interactions. Only the di-n-butyl derivative in the dialkyl series shows evidence of strong magnetic exchange interaction but of an antiferromagnetic nature; this effect is peculiar to the phase recrystallized from chloroform???light petroleum (??), the phase obtained from chloroform???ethanol (??) showing no such interaction. To seek the origin of the exchange interaction in the ?? derivative, its crystal structure has been determined by single-crystal X-ray diffraction methods at 295 K and refined by least squares to a residual 0.032 for 1 976 ???observed??? reflections. Crystals are triclinic, P, a= 15.29(1), b= 9.963(7), c= 9.243(7)??, ??= 67.94(7), ??= 82.92(7), ??= 71.55(7)??, and Z= 2. The copper environment is the usual pseudo-square-planar array of four sulphur atoms from two bidentate ligands (???Cu???S???, 2.31 ??), but there is a long fifth interaction [Cu S, 2.899(4)??] through the inversion centre leading to pseudo-dimer formation. Although similar to the diethyl analogue in this respect, differences are observed in regard to (a) the bridging geometry in the ???dimer??? and (b) the proximity to the ???dimer??? sulphur ligands of sulphur atoms from neighbouring dimers at ca. 3.8 ??. The likely relative importance of these two features in determining the origin of the antiferromagnetic coupling is discussed. The structure of the ?? phase has also been determined, the final residual being 0.036 for 1 324 ???observed??? reflections. Crystals are monoclinic, P21/n, a= 14.593(5), b= 7.840(2), c= 10.822(5)??, ??= 101.55(3)??, and Z= 2. The molecules are located with the copper atoms on crystallographic centres of symmetry, and the only significant intermolecular interactions observed are S H contacts. The CuS4 entity is planar with ???Cu???S??? 2.30 ??.

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  • Role of phosphine ligands in gold cluster chemistry. Relativistic SCF calculations on Au2 and Au2(PH3)2

    Schwerdtfeger, P; Boyd, Peter (1992)

    Journal article
    The University of Auckland Library

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  • Electrochemical And Electron-Spin-Resonance Studies Of Group-Viiidithioacetylacetone Complexes

    Boyd, Peter; ZVAGVLIS, M; Bowmaker, Graham (1983)

    Journal article
    The University of Auckland Library

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  • Antiferromagnetic Exchange in Triclinic Crystals of Tetra-$\mu $-Benzoato-bis(4-Methylquinoline) Dicobalt II

    Boyd, Peter; Davies, JE; Gerloch, MG (1978)

    Journal article
    The University of Auckland Library

    The magnetic susceptibilities of tetra-$\mu $-benzoato-bis(4-methylquinoline) dicobaltII have been measured and interpreted within the theoretical model described in the preceding paper. Crystals of the title complex are triclinic, a circumstance which has lead to the development of a new technique for the measurement of triclinic crystal susceptibilities using a Faraday balance. The technique is discussed in general terms and is applicable with Faraday equipment employing either longitudinal or, as here, transverse magnetic fields. The magnetic tensor for this binuclear cobalt complex has been determined throughout the temperature range 20-300 K. Good agreement between these results and those calculated from the quantum mechanical model have been obtained in the temperature range 90-300 K. At lower temperatures, a probable small paramagnetic impurity prevents useful theoretical treatment. There emerges an unambiguous conclusion that the antiferromagnetic coupling between the cobalt atoms is almost completely determined by interaction between metal $xy$ orbitals, presumably via a superexchange process involving the delocalized$\pi $ bonding framework of the bridging carboxylate groups.

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  • Spin spin interactions in polymeric copper(II) complexes: Cu(II)(piperidylcarbamate)2(Cu(I)X)4 (X = Cl, Br)

    Boyd, Peter; HOPE, J; MARTIN, RL (1980)

    Journal article
    The University of Auckland Library

    The reaction of copper(H) bis(N,N-dialkyldithio-carbamates) with copper(H) halides can lead to a variety of complexes containing copper(H) or copper- (II) and copper(I) ions [ 1, 21 . Bis(piperidyldithio-carbamate)copper(II), [Cu(pipdtc)?] reacts with copper(I1) halides leading to a series of compounds containing both copper(H) and copper(I) ions of the form Cu(II) (pipdtc)z(Cu(I)X), (X = Cl, Br, n = 4,6) [l , 21. X-ray crystal structures of the bromide com- plexes for n = 4,6 show them to consist of polymeric sheets of the copper(H) bisdithiocarbamate complex linked through Cu(I)Br chains, each copper(I1) ion being bridged to four copper(I) ions by the dithio- carbamate sulphur atoms [l] , Fig. 1. The analogous chloride complex Cu(II)(pipdtc),(CuC1)4 is iso-structural with the corresponding bromide com-pound.

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  • Single-Crystal Magnetic Susceptibility Study of the Linear-Chain Heisenberg Antiferromagnet Copper(I1) Pyrazine Nitrate

    Boyd, Peter; MITRA, S (1980)

    Journal article
    The University of Auckland Library

    There is considerable interest in the magnetic properties of polynuclear and polymeric transition-metal complexes bridged by small diaza heterocyclic molecule^^^^ such as pyrazine. The complex dinitro(pyrazine)copper(II), Cu(pz) ( N O , ) , consisting of linear chains of copper(I1) ions bridged by 1,Cpyrazine molecules (Figure l )...

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  • Spin???spin interactions in polynuclear nickel(II) complexes: a susceptibility and low-temperature magnetisation study of the linear trimer hexakis(allylamine)hexakis-??-benzotriazolyl-trinickel(II)???triphenylphosphine oxide (1/2)

    Boyd, Peter; MARTIN, RL (1981)

    Journal article
    The University of Auckland Library

    The linear title compound [Ni{Ni(N3C6H4)3[N(C3H5)H2]3}2]??2PPh3O has been studied using bulk magnetic susceptibility and magnetisation measurements in the range 2.0???300 K. The molecule has been found to have a spin-triplet ground state from an analysis of the high-temperature (>4.2 K) data and confirmed by the low-temperature (16???1.8 K) magnetisation results. The magnetic susceptibilities have been interpreted in terms of the Heisenberg???Dirac???Van Vleck isotropic exchange Hamiltonian. An antiferromagnetic interaction (J= 10 cm???1) occurs between adjacent atoms bridged by the benzotriazolyl molecules, and a small ferromagnetic interaction between the terminal ions. The mechanism of these interactions is discussed and compared with those found in similar molecules.

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  • Electron spin resonance spectra of the one-electron-reduction products of stannic chloride adducts of bis(dithiooxalato)nickelate(II), -palladate(II), and -platinate(II) complexes

    Bowmaker, Graham; Boyd, Peter; CAMPBELL, GK (1982)

    Journal article
    The University of Auckland Library

    Stannic chloride forms 1:l and 1:2 adducts with bis(di-thiooxalato)nickel(II) and bis(dithiooxalato)palladium(II) anionic complexes, [M(S2Cz02)2]2-, M = Ni, Pd, and a crystal structure determination for the 1:2 adduct of the nickel com-plex ( I ) showed tha t the SnC1, molecules are coordinated to the a-diketone oxygen atoms of the dithiooxalate ligands, which are themselves S-bonded to nickel as in the parent bis(dithiooxa1ato) complex. The coordination about Ni is square planar and that about S n is octahedral.

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  • Spin???spin interactions in the paired binuclear cluster tetrakis[??-chloro-diethyldithiocarbamatocopper(II)]

    Boyd, Peter; MARTIN, R (1977)

    Journal article
    The University of Auckland Library

    The magnetic susceptibility as a function of temperature between 4.2 and 300 K has been determined for the new tetrameric complex [(CuCI(S,CNEt,)),]. On the basis of the known X-ray crystal structure, it i s shown that the susceptibility can be interpreted in terms of three isotropic-exchange interactions acting between each of the four copper(ii) ions. I t i s established that the principal effect of the interdimer exchange interaction i s to lift the de- generacy of the two triplet-spin levels which characterise a pair of non-interacting dimers.

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  • Electrochemical and ESR studies of molybdenum-sulfur donor complexes. One-electron reduction of [cis-bis(N,N-dialkyldithiocarbamato)dinitrosyl]molybdenum and -tungsten complexes

    BUDGE, JR; BROOMHEAD, JA; Boyd, Peter (1982)

    Journal article
    The University of Auckland Library

    cis-M(R,dtc),(NO), complexes (M = M o o r W, R = Me, Et, i-Pr, n-Bu, Bzl, pyr) undergo a reversible one-electron reduction t o give t h e radical anion M(R,dtc),(NO);. E S R studies have shown t h a t t h e unpaired electron is delocalized over both nitrosyl groups. N o metal hyperfine couplings were observed. Analysis of frozen-solution E S R spectra of M o ( E t , d t ~ ) , ( ' ~ N 0 ) , a n d [Mo(Et,dtc),(NO),]- has yielded anisotropic g and nitrogen hyperfine tensors for these complexes. I n addition, t h e angle between the N O vectors remains essentially unchanged upon reduction of Mo(Et,dtc),(NO),. The s e observations strongly support the molecular orbital description of M(R$tc),(NO)<. Here, the unpaired electron resides in a dinitrosyl-based molecular orbital which possesses virtually no metal d-orbital character and which is close t o nonbonding between the two N O groups.

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  • Bis(1-ferrocenylbutane-1,3-dionato-kappa O-2,O ')copper(II) and bis(1,3-diferrocenylpropane-1,3-dionato-kappa O-2,O ')copper(II)

    Boyd, Peter; Johns, PM; Rickard, CEF (2006-12)

    Journal article
    The University of Auckland Library

    The title compounds, [CuFe2(C5H5)(2)(C9H8O2)(2)], (I), and [CuFe4(C5H5)(4)(C13H9O2)(2)], (II), are four-coordinate square-planar copper( II) complexes with two bidentate 1-ferrocenyl-butane-1,3-dionate or 1,3-diferrocenylpropane- 1,3-dionate ligands, respectively. The copper ion in ( I) lies on an inversion centre, with one-half of the molecule in the asymmetric unit, while in ( II), there are two independent half molecules in the asymmetric unit, with the copper ions also situated on inversion centres. The ferrocene substituents in ( I) are in an anti arrangement. The molecules assemble in the crystal structure in layers with ferrocene groups at the surface. The pairs of ferrocene substituents on each ligand in complex ( II) are syn and these adopt an anti arrangement with respect to the pair on the other diketonate ligand. As found in ( I), complexes assemble in a layered structure with ferrocene-coated surfaces.

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