134 results for Boyd, Peter, Journal article

  • Spin–spin interactions in polynuclear nickel(II) complexes: susceptibility and low-temperature magnetisation studies of tris[bis(pentane-2,4-dionato)nickel(II)]

    Boyd, Peter; MARTIN, RL (1979)

    Journal article
    The University of Auckland Library

    The magnetic susceptibility and magnetisation of the trinuclear complex [Ni3(pd)6](pd = pentane-2,4-dionate) have been reinvestigated in the range 1.8–300 K. Detailed magnetisation studies have been performed to low temperatures to evaluate the properties of the septet (S= 3) ground state of the molecule. The results have been analysed in terms of the Heisenberg–Dirac–Van Vleck isotropic exchange Hamiltonian including contributions from single-ion zero-field splittings. Ferromagnetic coupling between adjacent ions is confirmed, although the magnitude of both this interaction and the antiferromagnetic interaction between the terminal ions is found to be half that previously reported. This diminution is due to the effect of zero-field splitting on the low-temperature magnetic properties, the ground-state septet (S= 3) having a splitting of –1.3 cm–1.

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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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  • SCALED HARTREE-FOCK FORCE-FIELD CALCULATIONS FOR ORGANOTHALLIUM COMPOUNDS - NORMAL-MODE ANALYSIS FOR TLCH3, TL(CH3)2+, TL(CH3)3, TL(CH3)2BR, AND TL(CH3)4-

    SCHWERDTFEGER, P; Bowmaker, Graham; Boyd, Peter; Ware, David; Brothers, Penelope; NIELSON, A (1990-02)

    Journal article
    The University of Auckland Library

    In a recent paper we presented Hartree-Fock (HF) calculations for aliphatic organothallium compounds. The diagonal HF force constants obtained from a Fletcher-Powell geometry optimization are now used for a normal-mode analysis of TlCH,, Tl(CH,),+, T1(CH3),, T1(CHJ2Br, and Tl(CH3)c. In order to calculate frequencies comparable to experimental values, the HF force field has been scaled by using scaling factors obtained from experimental infrared and Raman measurements on T1(CH3)2+ and TlBr. The vibrational spectra of Tl(CH3)2+ were remeasured (infrared and Raman) in order to obtain an accurate force field. Predictions are made for the vibrational spectrum of the as yet undetected TlCH, molecule. Experimental infrared and Raman results for T1(CH3), compare reasonably well with our calculated frequencies (ex- perimental v,,(Tl-C) = 450 cm-', v,,(Tl-C) = 465 cm-l, v,,(C-H) = 2917 cm-l, v,,(C-H) = 3020 cm-l; scaled HF u,,(Tl-C) = 488 cm-', v,,(Tl-C) = 514 cm-', vSp(C-H) = 2892 cm-l, Y, (C-H) = 2999 cm-l). Relativistic and correlation effects are analyzed for the vibrational frequencies ~ f i l ( C H , ) ~ +

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  • SPIN SPIN INTERACTIONS IN POLYNUCLEAR NICKEL(II) COMPLEXES - A MAGNETIC AND STRUCTURAL STUDY OF BINUCLEAR NICKEL(II) COMPLEXES OF ENOLIC 1,3,5-TRIKETONATES

    Boyd, Peter; LEE, KS; ZVAGULIS, M (1986-01-01)

    Journal article
    The University of Auckland Library

    The bulk magnetic susceptibilities of the binuclear nickel(11) complexes of the 1,3,5- triketonates from diethyl (2-oxocyclopentane-1,3-diy1)bisglyoxylate (H2ecg) (1) and diethyl 2,4,6-trioxoheptanedioate (H2decg) (2) have been measured over the temperature range 6-300 K. Antiferromagnetic spin-spin coupling is observed in each case with Nee1 temperatures in the range 45-65 K. The X-ray crystal structure of [ N i ( e ~ g ) ( p y ) ~ ] ~ . ( p y ) has been solved. The complex crystallize! with one pyridine of solvation in the space group PT [ a 10.507(1), b 13.384(1), c g q 9 9 2 ( 1 ) A, a 103.004(9), /3 115.867(9), y 86.857(10)", Z = 11. The molecule is binuclear with two coplanar triketonate dianions bridging the two six-coordinate nickel atoms through a di-p-0x0 linkage [Ni-Ob-Ni angle 102.0(1)"]. Two pyridine molecules and four triketonate oxygen atoms are bound to each nickel atoms. Magnetostructural correlations are presented in comparison with binuclear copper(11) 1,3,5- triketonates. The marked decrease in spin-spin interaction in the nickel complexes is attributed to increasing metal-bridging oxygen bond lengths that decrease the efficacy of the u antiferromagnetic pathway xyllOb 1 x y and contributions from the ferromagnetic xyllOb / / z2 pathway.

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  • 2-Methyl-4-hydroxymethyl-5-carboxyethyl-pyridine.

    Boyd, Peter; Lena, G; Spicer, Julie (2008)

    Journal article
    The University of Auckland Library

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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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  • Corrole as a binucleating ligand: Preparation, molecular structure and density functional theory study of diboron corroles

    Albrett, AM; Conradie, J; Boyd, Peter; Clark, George; Ghosh, A; Brothers, Penelope (2008)

    Journal article
    The University of Auckland Library

    The reactions of BF3 center dot OEt2 with four triaryl corroles (H3Cor) give the complexes [(B2OF2)(Cor)]- in which the corrole acts as a binucleating ligand. The new complexes were fully characterized, including an X-ray crystal structure of the triphenylcorrole complex. Density functional theory calculations support the observation that the boron atoms coordinate in two dipyrromethene sites in a cisoid geometry on one face of the macrocycle rather than in the alternative dipyrromethene/bipyrrole sites. The UV-visible spectra are insensitive to the corrole substituents, consistent with the lack of low-lying orbitals associated with the coordinated boron atoms.

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  • Diboryl and diboranyl porphyrin complexes: Synthesis, structural motifs and redox chemistry: Diborenyl porphyrin or diboranyl isophlorin?

    Weiss, A; Hodgson, MC; Boyd, Peter; Siebert, W; Brothers, Penelope (2007-01)

    Journal article
    The University of Auckland Library

    The syntheses of diboryl porphyrin complexes [(BX2)(2)(ttp)] (ttp: dianion of tetra-p-tolylporphyrin) and the B-B single-bond diboranyl complexes [(BX)(2)(ttp)] (X=F, Cl, Br, I) are given. The former are prepared from the reactions of BX3 (X=F, Cl) with [Li-2(ttp)] and the latter from B2Cl4 (X=Cl), the reaction of SbF3 with [(BCl)(2)(ttp)] (for X=F), and, in the cases of X=Br or I, in a remarkable reductive coupling reaction resulting directly from the reaction of BBr3 or BI3 with [Li-2(ttp)]. Density functional theory (DFT) calculations on the thermochernical parameters for the reductive coupling reactions (and those calculated for related dipyrromethene complexes) indicate that a combination of the reducing ability of bromide and iodide ions combined with the constrained environment of the porphyrin ligand contribute to the driving force. The reductive coupling is also observed in the reaction of [(BCl2)(2)(ttp)] with nBuLi to give [(BnBU)(2)(ttp)], which was characterised crystallographically. The reaction of [(BCl)(2)(ttp)] with catechol gives a boron catecholato porphyrin complex, [B-2(O2C6H4)(ttp)] Chloride abstraction from [(BCl)(2)(ttp)] gives the planar dication [B-2(ttp)](2+), whereas chemical reduction of [(BCl)(2)-(ttp)] by using magnesium anthracenide gives a neutral complex, [B-2(ttp)], in which the ttp ligand has been reduced by two electrons to give an unusual example of an isophlorin complex. The cationic and neutral complexes [B-2(ttp)](2+) and [B-2(ttp)] were characterised through a combination of spectroscopic data that is supported by DFT calculations on the porphine analogues.

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  • Densities and molar volumes for the molten salt systems ZnBr2 + KBr, CdI2 + NaI and CdI2 + CsI

    BLOOM, H; BENDALL, MR; Boyd, Peter; LAVER, JL (1974)

    Journal article
    The University of Auckland Library

    Densities of binary mixtures of ZnBr2 + KBr, CdI2 + NaI and CdI2 + CsI, have been measured by an Archimedian method over a wide range of temperature. Results have been expressed in terms of simple linear equations in temperature. Molar volumes for the systems have excess values in the ZnBr2 + KBr and CdI2 + CsI systems but not to such an extent in the CdI2+NaI system. The excess molar volumes are related to the possible formation of complex ions in the systems concerned.

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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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  • NEW COORDINATION MODE FOR THE PORPHYRIN LIGAND IN THE BORON PORPHYRIN COMPLEX B2OF2(TTP)

    BELCHER, WJ; Boyd, Peter; Brothers, Penelope; LIDDELL, MJ; RICKARD, CEF (1994-09-07)

    Journal article
    The University of Auckland Library

    The predominant mode of porphyrin ligand t o metal coordination involves the interaction of all four pyrrolic nitrogen atoms with a single metallic element t o form four-, five-, or six-coordinate complexes. ...

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  • Porphyrin-fullerene host-guest chemistry

    sun, D; Tham, FS; Reed, CA; Chaker, L; Burgess, M; Boyd, Peter (2000)

    Journal article
    The University of Auckland Library

    Fullerenes are spontaneously attracted to porphyrins and metalloporphyrins. This new supramolecular recognition element was first discovered in cocrystallates of C60 and C70 with tetraarylporphyrins and octaethylmetalloporphyrins. ...

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  • 2-[Bis(2-bromoethyl)amino]-N-(2-hydroxyethyl)-3,5-dinitrobenzamide .

    Atwell, Graham; Boyd, Peter; Denny, William; Yang, S (2006)

    Journal article
    The University of Auckland Library

    The title compound, C13H16Br2N4O6, is a dinitrobenzamide dibromo mustard. The tetrasubstituted benzene ring is significantly distorted from both planarity and ideal hexagonal symmetry. The molecules assemble in the crystal structure via hydrogen-bonding interactions between the amide groups on adjacent molecules, and by O-HO(nitro) and O-HBr contacts. There are short BrBr contacts (3.388 ??) that are significantly less than the sum of the van der Waals radii of two Br atoms.

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  • [7,16-Dibenzyloxycarbonyl-6,18,15,17-tetramethyldibenzo[b,i][1,4,8,11] tetraazacyclotetradecinato-]nickel(II)

    Boyd, Peter; Challis, JB; Rickard, Clifton (2006)

    Journal article
    The University of Auckland Library

    The title compound, [Ni(C38H34N4O4)], is a four-coordinate nickel(II) complex of the 5,15-dihydro-7,16-bis(benzyloxycarbonyl)-6,18,15,17-tetramethyldibenzo[b,i][1,4,8,11]tetraazacyclotetradecine ligand, which forms a saddle-shaped molecule with divergent concave surfaces. The molecules assemble in the crystal structure via C-HO interactions with the ester carbonyl O atoms and C-H interactions with the propanediiminate portion of the complex.

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  • A supramolecular porphyrin-ferrocene-fullerene triad

    Lyons, DM; Mohanraj, J; Accorsi, G; Armaroli, N; Boyd, Peter (2011)

    Journal article
    The University of Auckland Library

    A ferrocene (Fc) functionalized bis-porphyrin molecule has been synthesized as a host for fullerenes. The porphyrin used in these studies was prepared using a mixed boronic acid Suzuki reaction, which gives A(2)BC type porphyrins in high yield. The bis-porphyrin was characterized through H-1 NMR spectroscopy, high-resolution mass spectroscopy and analyzed via molecular modeling studies. Complexation experiments with fullerenes utilizing both UV-visible and fluorescence spectroscopy demonstrated formation of strong complexes for the bis-porphyrin. A short-lived charge transfer luminescent state is detected for the fullerene adducts. Owing to the tight coupling of the fullerene and porphyrin partners, the host-appended Fc moiety does not show a direct role in the pattern of photoinduced processes upon excitation of either chromophores, but causes blue-shift of the NIR CT luminescence compared to previously investigated systems without appended fragments. Instead, the active role of Fc in photoinduced processes is observed for the guest molecules alone, where photoinduced energy transfer from the porphyrin to the ferrocene occurs.

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  • A double Mannich approach to the synthesis of substituted piperidones-application to the synthesis of substituted E-ring analogues of methyllycaconitine

    Chan, YM; Balle, J; Sparrow, JK; Boyd, Peter; Brimble, Margaret; Barker, David (2010-08-28)

    Journal article
    The University of Auckland Library

    The double Mannich reaction of acyclic alpha,gamma-substituted beta-keto esters and bis(aminol) ethers gives substituted 3,5-substituted-4-piperidones with high levels of diastereoselectivity. These piperdiones can be easily transformed into substituted E-ring analogues of the delphinium alkaloid methyllycacotine. (C) 2010 Elsevier Ltd. All rights reserved.

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  • Nucleation of Antiferromagnetically Coupled Chromium Dihalides: from Small Clusters to the Solid State

    Vest, B; Hermann, A; Boyd, Peter; Schwerdtfeger, P (2010-04-05)

    Journal article
    The University of Auckland Library

    The nucleation of chromium dihalide clusters is investigated by studying clusters of the form CrnX2n (n three-dimensional geometry takes slight precedence over the planar ribbon motif. We find that each single CrX2 unit adds an almost constant amount of energy between 45 and 50 kcal/mol to the cluster growth. This is in accordance with the calculated sublimation energies for the solid state which gave 58 kcal/mol for CrF2, and between 41 and 46 kcal/mol for CrCl2, CrBr2, and Crl(2). The large deviation of the calculated from the experimental sublimation energy for CrF2 is due to the high electronegativity of fluorine ligand, which substantially increases the ionic interactions, resulting in a much more tightly packed solid-state structure, which is not so well described by spin-broken density functional theory. In accordance with this, CrF2 shows an unusually large bulk modulus (395 kbar) compared to the heavier halides CrCl2 (82 kbar), CrBr2 (40 kbar), and Crl(2) (18 kbar).

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  • Density Functional Theory Study on the Mechanism of the Reductive Cleavage of CO2 by a Bis-beta-Diketoiminatediiron Dinitrogen Complex

    Ariafard, A; Brookes, NJ; Stranger, R; Boyd, Peter; Yates, BF (2010-09-06)

    Journal article
    The University of Auckland Library

    Density functional theory has been used to analyze the detailed reaction mechanism for the reductive cleavage of CO2 by a dinitrogen bridged bis-beta-diketoiminatediiron complex, (LFe)-Fe-tBu-N-2-FeLtBu (I), recently reported by Holland and co-workers. A number of pathways have been investigated and the most likely mechanism correlates well with experimental evidence. A rationale has been provided for the binding of CO2, the release of CO, and the ready formation of CO32-. Our results show that the insertion of CO2 into the diiron complex is the rate determining step of the reductive cleavage reaction. An intramolecular reduction step from the reduced dinitrogen bridge is proposed which serves to increase the activation of CO2. This is followed by an intersystem crossing from the septet to the nonet state which acts as a driving force for the subsequent release of CO. The overall reductive cleavage reaction is exergonic by 120 kJ/mol, and further reaction of the released CO with the starting diiron complex is also predicted to be strongly exergonic.

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  • Characterization of dicarboxylic salts of protonated triethylenetetramine useful for the treatment of copper-related Pathologies

    Soehnel, Kathrin; Boyd, Peter; Sohnel, T; Allen, GR; Phillips, Anthony; Cooper, Garth (2007-09)

    Journal article
    The University of Auckland Library

    X-ray crystal structures of three salts of protonated triethylenetetramine, (H(4)TETA)(4+), with succinate, maleate, and fumarate anions are reported. Structures of the complexes (H-4-triethylenetetramine)(hydrogenmaleate)(4)center dot 2H(2)O [(H(4)TETA)(Hmal)(4)center dot 2H(2)O] (1), (H4-triethylenetetramine)(hydrogenfumarate)(4)center dot 3.3H(2)O [(H(4)TETA)(HfuM)(4)center dot 3.3H(2)O] (2), and (H-4-triethylenetetramine)(succinate)(2) [(H(4)TETA)(suc)(2)] (3) all form assemblies of alternating two-dimensional layers of (H(4)TETA)(4+) and the anionic species via hydrogen-bond networks. Both classical and nonclassical hydrogen bonds between the protonated amine groups, anions, and water molecules were observed. X-ray powder diffraction measurements, differential thermal analysis/thermogravimetry, density vapor sorption, and Karl Fischer titration measurements were performed to obtain confirmatory information about the water content in the structures 1 and 2 and to examine polymorphism within the salts. The nonhydrated salt 3 was determined to be the most favorable salt formulation for use in medicinal applications.

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  • Fullerene-porphyrin constructs

    Boyd, Peter; Reed, CA (2005)

    Journal article
    The University of Auckland Library

    Porphyrins and fullerenes are spontaneously attracted to each other. This new supramolecular recognition element can be used to construct discrete host???guest complexes, as well as ordered arrays of interleaved porphyrins and fullerenes. The fullerene???porphyrin interaction underlies successful chromatographic separations of fullerenes, and there are promising applications in the areas of porous framework solids and photovoltaic devices.

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