113 results for Henderson, William, Journal article

  • Self-assembly of a columnar polymeric calcium phosphinate derived from camphene

    Henderson, William; Leach, Meto T.; Nicholson, Brian K.; Sabat, Michal (1995)

    Journal article
    University of Waikato

    (2,2-Dimethylbicyclo[2.2.1] hept-3-ylmethyl)phosphinic acid (RPO₂H₂), readily prepared from camphene and hypophosphorous acid, formed a polymeric calcium salt [{Ca(RPO₂H) ₂ (RPO₂H₂)(H₂O)}n], with both terminal and triply bridging phosphinate groups, and an overall columnar structure with an inorganic core and a pseudo-close-packed sheath of terpene moieties.

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  • Study of metal scrambling in the trinuclear {Pt₂Se₂M} (M = Pt, Pd, Au) system using an electrospray mass spectrometry (ESMS) directed synthetic methodology; isolation and crystallographic characterization of {Pt₂(µ₃-Se)₂(PPh₃)₄[Pt(cod)]}{PF₆}₂ and {Pt(μ₃-Se)₂(PPh₃)₂[Pt(cod)]₂}{PF₆}₂ (cod = Cyclo-octa-1,5-diene)

    Yeo, Jeremy S.L.; Vittal, Jagadese J.; Henderson, William; Hor, T.S. Andy (2002)

    Journal article
    University of Waikato

    Pt₂(μ-Se)₂(PPh₃)₄ reacts with PtCl₂(cod) to give {Pt₂(μ₃-Se)₂(PPh₃)₄[Pt(cod)]}²⁺ and an unexpected cod-rich product that arises from metal scrambling, viz. {Pt(μ₃-Se)₂(PPh₃)₂[Pt(cod)]₂}²⁺. The formation of these species was detected and followed by electrospray mass spectrometry (ESMS) and subsequently verified by batch synthesis and crystallographic characterization. Other metal-scrambled aggregate products were successfully detected.

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  • Use of cyclometallated PdCl[PPh₂CH₂CH₂CHCH₂CH₂PPh₂] as a precursor to homo and heterometallic species directed by ESMS (Electrospray Ionisation Mass Spectrometry)

    Neo, Kian Eang; Neo, Yew Chin; Chien, Sheau Wei; Tan, Geok Kheng; Wilkins, Alistair L.; Henderson, William (2004)

    Journal article
    University of Waikato

    The cyclometallated Pd compound PdCl[PPh₂CH₂CH₂CHCH₂CH₂PPh₂] 1, obtained from PdCl₂(Ph₂P(CH₂)₅PPh₂) in refluxing DMF (N,N-dimethylformamide), was characterized by NMR and X-ray single-crystal diffraction analysis. The cyclometallation of MCl₂(Ph₂P(CH₂)₅PPh₂)(M = Pd, Pt) to give 1 and its Pt(II) analogue was probed using electrospray ionisation mass spectrometry (ESMS). The reactivity of 1 towards neutral ligands such as phosphines and pyridines as well as basic metal complexes such as pyridine-thiolate compounds of Au(I), Hg(II) and Pt(II) in solution was also investigated. The results showed that the chloride trans to the Pd–C bond is susceptible to ligand replacement. A number of entry metalloligands was examined in an attempt to establish a route to cyclometallated aggregates and clusters.

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  • E/Z isomerism in monoalkylated derivatives of [Pt₂(μ-S)₂(PPh₃)₄] containing 2,4-dinitrophenylhydrazone substituents

    Ujam, Oguejiofo Theophilus; Devoy, Sarah M.; Henderson, William; Wilkins, Alistair L.; Nicholson, Brian K. (2011)

    Journal article
    University of Waikato

    Alkylation of [Pt₂(m-S)₂(PPh₃)₄] with 2,4-dinitrophenylhydrazone-functionalized alkylating agents XC6H4C{¼NNHC₆H₃(NO₂)₂}CH2Br (X¼H, Ph) gives monoalkylated cations [Pt₂(m-S){m-SCH₂C{¼NNHC₆H₃(NO₂)₂}C₆H₄X}(PPh₃)₄]⁺. An X-ray diffraction study on [Pt₂(m-S){m-SCH₂C{¼NNHC₆H₃(NO₂)₂}Ph}(PPh₃)₄]BPh₄ shows the crystal to be the Z isomer, with the phenyl ring and NHC₆H₃(NO₂)₂ groups mutually trans. ¹H- and ³¹P{¹H} NMR spectroscopic methods indicate a mixture of Z (major) and E (minor) isomers in solution, which slowly convert mainly to the E isomer. Reaction of [Pt₂(m-S)₂ (PPh₃)₄] with the dinitrophenylhydrazone of chloroacetone [ClCH₂C{¼NNH(C₆H₃(NO₂)₂}Me] and NaBPh₄ gives [Pt₂ (m-S){m-SCH₂C{¼NNHC₆H₃(NO₂)₂}Me}(PPh₃)₄]BPh₄, which exists as a single (E) isomer.

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  • Cycloaurated GoId (III) complexes- Possible alternatives to cisplatin?

    Kilpin, Kelly Joan; Henderson, William (2009-07)

    Journal article
    University of Waikato

    The serendipitous discovery of the anti-tumour activity of cisplatin [cis-PtCI₂(NH₃)₂] in 1969 has led to increased interest in the development of new metal-based anti-cancer drugs. However, regardless of the large numbers of new metal-containing compounds generated, many of which demonstrate anti-tumour activity, cisplatin still remains one of the most widely used anti-tumour drugs in the western world.

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  • Electrospray ionisation - a simple prelude to the understanding of other mass spectrometry techniques

    Henderson, William (2015-07)

    Journal article
    University of Waikato

    Mass spectrometry (MS) is a powerful analytical technique used in the characterisation of a wide range of chemical and biochemical substances. The technique is extensively used in research, across a wide range of disciplines. One of the main strengths of mass spectrometry is that miniscule amounts of sample are typically needed, in the order of micrograms or less. While the study of spectroscopic techniques has been a part of qualifications such as the International Baccalaureate Diploma for some time, ¹ a new Achievement Standard on Spectroscopy has been introduced relatively recently into the New Zealand Chemistry Curriculum, which includes the technique of electron ionisation (El) mass spectrometry.² This article aims to provide, for those perhaps encountering mass spectrometry for the very first time, a short discussion on electrospray ionisation mass spectrometry as an alternative introduction to this important analytical technique.

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  • The chemistry and metallurgy of beryllium

    Raymond, Onyekachi; Perera, Lakshika C.; Brothers,, Penelope J.; Henderson, William; Pleiger, Paul G. (2015-07)

    Journal article
    University of Waikato

    Beryllium (Be), the first of the group 2 alkali-earth ele­ments, is a silver-gray metal possessing an unmatched combination of physical and mechanical properties, which are vital for a variety of applications that offer tre­mendous benefits to society. It is the lightest workable metal, only two-thirds the weight of aluminium, yet it has six times the stiffness of steel, making it an ideal mate­rial for stiffness-dependent and weight-limited applica­tions. The chart in Fig. 1 illustrates how much beryllium outclasses other engineering materials with respect to thermal conductivity and dimensional stability (ability of a material to retain its uniformity under stress measured as the Young's modulus to density ratio). These unique properties of beryllium translate into performance en­hancement in the end product, for instance the James Webb Space Telescope (JWST: see Fig. 2). The next gen­eration James Webb Space Telescope, scheduled to be launched in 2018 as NASA's replacement for the Hubble telescope, will utilise a 6.5 meter wide beryllium mirror to reveal images of distant galaxies 200 times beyond what has ever been sighted.

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  • Ferrocenyl hydroxymethylphosphines (η⁵-C₅H₅)Fe[η⁵⁻C₅H₄P(CH₂OH)₂] and 1,1′-[Fe{η⁵-C₅H₄P(CH₂OH)₂}₂] and their chalcogenide derivatives

    Henderson, William; Alley, Steven R. (2002)

    Journal article
    University of Waikato

    The ferrocenyl hydroxymethylphosphines FcP(CH₂OH)₂ [Fc=(η⁵-C₅H₅)Fe(η⁵-C₅H₄)] and 1,1′-Fc′[P(CH₂OH)₂]₂ [Fc′=Fe(η⁵⁻C₅H₄)₂] were prepared by reactions of the corresponding primary phosphines FcPH₂ and 1,1′-Fc′(PH₂)₂ with excess aqueous formaldehyde. The crystal structure of FcP(CH₂OH)₂ was determined and compared with the known ferrocenyl hydroxymethylphosphine FcCH₂P(CH₂OH)₂. The chalcogenide derivatives FcP(E)(CH₂OH)₂ and 1,1′-Fc′[P(E)(CH₂OH)₂]₂ (E=O, S, Se) were prepared and fully characterised. Crystal structure determinations on FcP(O)(CH₂OH)₂ and FcP(S)(CH₂OH)₂ were performed, and the hydrogen-bonding patterns are compared with related compounds. The sulfide shows no hydrogen-bonding involving the phosphine sulfide group, in contrast to other reported ferrocenyl hydroxymethylphosphine sulfides. The platinum complex cis-[PtCl₂{FcP(CH₂OH)₂}₂] was prepared by reaction of 2 mol equivalents of FcP(CH₂OH)₂ with [PtCl₂(1,5-cyclo-octadiene)], and was characterised by 31P-NMR spectroscopy and negative ion electrospray mass spectrometry, which gave a strong [M+Cl]⁻ ion.

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  • The arylation of [Pt₂(μ-S)₂(PPh₃)₄]

    Deadman, Benjamin Jade; Henderson, William; Nicholson, Brian K.; Petchell, Laura Eleanor; Rose, Sarah L.; Hor, T.S. Andy (2009)

    Journal article
    University of Waikato

    Routes to the synthesis of the mixed sulfide-phenylthiolate complex [Pt₂(μ-S)(μ -SPh)(PPh₃)₄]⁺ have been explored; reaction of [Pt₂(μ-S)₂(PPh₃)₄] with excess Ph₂IBr proceeds readily to selectively produce this complex, which was structurally characterised as its PF₆⁻ salt. Reactions of [Pt₂(μ-S)₂(PPh₃)₄] with other potent arylating reagents (1-chloro-2,4-dinitrobenzene and 1,5-difluoro-2,4-dinitrobenzene) also produce the corresponding nitroarylthiolate complexes [Pt₂(μ-S){μ -SC₆H₂(NO₂)₂X}(PPh₃)₄]⁺ (X = H, F). The complex [Pt₂(μ-S)(μ -SPh)(PPh₃)₄]⁺ reacts with Me₂SO₄ to produce the mixed alkyl/aryl bis-thiolate complex [Pt₂(μ-SMe)(μ -SPh)(PPh₃)₄]²⁺, but corresponding reactions with the nitroarylthiolate complexes are plagued by elimination of the nitroaryl group and formation of [Pt₂(μ-SMe)₂(PPh₃)₄]²⁺. [Pt₂(μ-S)(μ -SPh)(PPh₃)₄]⁺ also reacts with Ph₃PAuCl to give [Pt₂(μ-SAuPPh₃)(μ -SPh)(PPh₃)₄]²⁺.

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  • Synthesis and structure of the amidate-bridged platinum-uranium bimetallic complex [Pt{NC(O)CH₂CH₂}₂(PPh₃)₂].UO₂(NO₃)₂

    Henderson, William; Oliver, Allen G.; Rickard, Clifton E.F. (2000)

    Journal article
    University of Waikato

    The reaction of the β-propiolactam-derived platinum(II) amidate complex [Pt{NC(O)CH₂CH₂}₂(PPh₃)₂]with uranyl nitrate gives the coordination complex [Pt{NC(O)CH₂CH₂}₂(PPh₃)₂].UO₂(NO₃)₂, which was characterised by a single-crystal X-ray diffraction study. The lactam carbonyl groups are coordinated to the linear uranyl group, forming an eight-membered ring, with the uranium also having two bidentate nitrates, completing a hexagonal bipyramidal coordination geometry. The platinum and uranium coordination planes are almost perpendicular, at an angle of 85.4(1)°.

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  • Platinum(II) phosphonate complexes derived from endo-8-camphanylphosphonic acid

    Leach, Meto T.; Henderson, William; Wilkins, Alistair L.; Lane, Joseph R.; Fortney-Zirker, Ryland G.; Turnbull, Mark M.; Nicholson, Brian K. (2011)

    Journal article
    University of Waikato

    The reactions of cis-[PtCl₂L₂] [L = PPh₃, PMe₂Ph or L₂ = Ph₂P(CH₂)₂PPh₂ (dppe)] with endo-8-camphanylphosphonic acid (CamPO₃H₂) and Ag₂O in refluxing dichloromethane gave platinum(II) phosphonate complexes [Pt(O₃PCam)L₂]. The X-ray crystal structure of [Pt(O₃PCam)(PPh₃)₂]•₂CHCl₃ shows that the bulky camphanyl group, rather than being directed away from the platinum, is instead directed into a pocket formed by the Pt and the two PPh₃ ligands. This allows the O₃P–CH₂ group to have a preferred staggered conformation. The complexes were studied in detail by NMR spectroscopy, which demonstrates non-fluxional behaviour for the sterically bulky PPh₃ and dppe derivatives, which contain inequivalent phosphine ligands in their ³¹P NMR spectra. These findings are backed up by theoretical calculations on the PPh₃ and PPhMe₂ derivatives, which show, respectively, high and low energy barriers to rotation of the camphanyl group in the PPh₃ and PPhMe₂ complexes. The X-ray crystal structure of CamPO₃H₂ is also reported, and consists of hydrogen-bonded hexameric aggregates, which assemble to form a columnar structure containing hydrophilic phosphonic acid channels surrounded by a sheath of bulky, hydrophobic camphanyl groups.

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  • Tricarbonylrhenium(I) complexes of phosphine-derivatized amines, amino acids and a model peptide: structures, solution behavior and cytotoxicity

    Zhang, Jianyong; Vittal, Jagadese J.; Henderson, William; Wheaton, Jessica R.; Hall, Iris H.; Hor, T.S. Andy; Yan, Yaw Kai (2002)

    Journal article
    University of Waikato

    Modified Mannich reactions of amines, amino acids and a model peptide with Ph₂PH and CH₂O gave bis(diphenylphosphinomethyl)amines (Ph₂PCH₂)₂NR [R=Ph (1), CH₂CH₂OH (2), CH₂COOCH₂Ph (3), CH₂CONHCH₂COOCH₂Ph (4), CH2COOH (5)] and (Ph₂PCH₂)₂NCH₂CH₂N(CH₂PPh₂)₂ (6). Reaction with [ReBr₃(CO)₃]²⁻ under mild conditions led to [ReBr(CO)₃]{(Ph₂PCH₂)₂NR} [R=Ph (7), CH₂CH₂OH (8), CH₂COOCH₂Ph (9), CH₂CONHCH₂COOCH₂Ph (10), CH₂COOH (11)] and [ReBr(CO)₃(Ph₂PCH₂)₂NCH₂]₂ (12). All new complexes have been characterized by NMR and IR spectroscopy and for 7, 9 and 10, single-crystal X-ray diffraction analyses. Electrospray mass spectrometric studies show that the rhenium–phosphine chelates are very stable, especially in neutral methanolic solution. Hydrolysis of the ester and amide linkages slowly occur in acidic and basic solutions over several weeks; displacement of the bromide ligand also occurs in basic medium. Cytotoxicity testing of 7–10 and 12 showed that all the complexes are active against specific tumor cell lines, especially MCF-7 breast cancer and HeLa-S3 suspended uterine carcinoma.

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  • ‘User-friendly’ primary phosphines and an arsine: synthesis and characterization of new air-stable ligands incorporating the ferrocenyl group

    Henderson, William; Alley, Steven R. (2002)

    Journal article
    University of Waikato

    Reaction of FcCH₂CH₂P(O)(OH)₂ or FcCH₂P(O)(OH)(OEt) [Fc=Fe(η⁵-C₅H₄)(η⁵-C₅H₅)] with excess CH₂N₂ followed by reduction with Me₃SiCl–LiAlH₄ gives the air-stable primary phosphines FcCH₂CH₂PH₂ and the previously reported analogue FcCH₂PH₂ in high yields. Reduction of 1,1′-Fc′[CH₂P(O)(OEt)₂] [Fc′=Fe(η⁵-C₅H₄)₂] and 1,2-Fc″[CH₂P(O)(OEt)₂] [Fc″=Fe(η⁵-C₅H₅)(η⁵-C₅H₃)] similarly gives the new primary phosphines 1,1′-Fc′(CH₂PH₂)₂ and 1,2-Fc″(CH₂PH₂)₂, respectively. The arsine FcCH₂CH₂AsH₂, which is also air-stable, has been prepared by reduction of the arsonic acid FcCH₂CH₂As(O)(OH)₂ using Zn/HCl. An X-ray structure has been carried out on the arsine, which is only the second structure determination of a free primary arsine. The molybdenum carbonyl complex [1,2-Fc″(CH₂PH₂)₂Mo(CO)₄] was prepared by reaction of the phosphine with [Mo(CO)₄(pip)₂] (pip=piperidine), and characterized by a preliminary X-ray structure determination. However, the same reaction of 1,1′-Fc′(CH₂PH₂)₂with [Mo(CO)₄(pip)₂] gave [1,1′-Fc′(CH₂PH₂)₂Mo(CO)₄] and the dimer [1,1′-Fc′(CH₂PH₂)₂Mo(CO)₄]₂, characterized by electrospray mass spectrometry. 1,1′-Fc′[CH₂PH₂Mo(CO)₅]₂ and 1,2-Fc″[CH₂PH₂Mo(CO)₅]₂ were likewise prepared from the phosphines and excess [Mo(CO)₅(THF)].

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  • Coordination chemistry of the metalloligand [Pt₂(μ-S)₂(PPh₃)₄] with nickel(II) complexes – an electrospray mass spectrometry directed synthetic study

    Fong, S.W. Audi; Hor, T.S. Andy; Vittal, Jagadese J.; Henderson, William; Cramp, Shelley (2004)

    Journal article
    University of Waikato

    The reactivity of [Pt₂(μ-S)₂(PPh₃)₄] towards a range of nickel(II) complexes has been probed using electrospray ionisation mass spectrometry coupled with synthesis and characterisation in selected systems. Reaction of [Pt₂(μ-S)₂(PPh₃)₄] with [Ni(NCS)₂(PPh₃)₂] gives [Pt₂(μ-S)₂(PPh₃)₄Ni(NCS)(PPh₃)]⁺, isolated as its BPh₄ ⁻ salt; the same product is obtained in the reaction of [Pt₂(μ-S)₂(PPh₃)₄] with [NiBr₂(PPh₃)₂] and KNCS. An X-ray structure determination reveals the expected sulfide-bridged structure, with an N-bonded thiocyanate ligand and a square-planar coordination geometry about nickel. A range of nickel(II) complexes NiL₂, containing β-diketonate, 8-hydroxyquinolinate, or salicylaldehyde oximate ligands react similarly, giving [Pt₂(μ-S)₂(PPh₃)₄NiL]⁻ cations. Reactions of [Pt₂(μ-S)₂(PPh₃)₄] with a range of nickel(II) substrates have been explored using electrospray mass spectrometry, coupled with synthesis and characterization in selected systems. The X-ray crystal structure of [Pt₂(μ-S)₂(PPh₃)₄Ni(NCS)(PPh₃)]⁺PF₆⁻is reported.

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  • (p -Cymene)thioglycollatoruthenium(II) dimer; a complex with an ambi-basic S,O-donor ligand

    Henderson, William; Kilpin, Tracey D.; Nicholson, Brian K. (2007)

    Journal article
    University of Waikato

    The title compound was prepared from the (p-cymene)ruthenium chloride dimer and thioglycollic acid. The structure is a centrosymmetric dimer bridged by the soft-base S atoms, with the hard-base O atoms of the carboxylate group chelating to form a five-membered twisted-ring. The coordination of the ruthenium atoms is completed by a η6-p-cymene ligand, giving an 18-electron count. The Ru–S bonds are essentially equal at 2.396(1) Å.

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  • The cycloauration of pyridine-2-thiocarboxamide ligands

    Kilpin, Kelly Joan; Henderson, William; Nicholson, Brian K. (2010)

    Journal article
    University of Waikato

    Reactions of H[AuCl₄] with N-substituted 2-pyridine thiocarboxamide ligands 2-(C₅H₄N)C(S)NHR (R= p-C₆H₄Me, CH₂Ph, Me, p-C₆H₄OMe) gave cycloaurated derivatives {(C₅H₄N)C(S)NR}AuCl₂, with the ligand bonded as the thiol tautomer through the deprotonated SH group and the pyridine N atom to give a five-membered metallacyclic ring. The X-ray structure determination of the R = CH₂Ph derivative shows a square-planar gold(III) complex that dimerises in the solid state by weak Au...S intermolecular interactions. In contrast, in the reaction of H[AuCl₄] with 2-(C₅H₄N)C(S)NHR where R = 2-pyridyl, the ligand was oxidised to give a 1,2,4-thiadiazolo[2,3-a]pyridinium heterocyclic ring that was crystallographically characterised.

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  • Thallium(III) complexes of the metalloligands [Pt₂(μ-S)₂(PPh₃)₄] and [Pt₂(μ-Se)₂(PPh₃)₄]

    Rose, Sarah L.; Henderson, William; Nicholson, Brian K.; Hor, T.S. Andy (2009)

    Journal article
    University of Waikato

    Reactions of [Pt₂(μ-S)₂(PPh₃)₄] with the diarylthallium(III) bromides Ar₂TlBr [Ar = Ph and p-ClC₆H₄] in methanol gave good yields of the thallium(III) adducts [Pt₂(μ-S)₂(PPh₃)4TlAr₂]⁺, isolated as their BPh₄⁻ salts. The corresponding selenide complex [Pt₂(μ-Se)₂(PPh₃)₄TlPh₂]BPh₄ was similarly synthesised from [Pt₂(μ-Se)₂(PPh₃)₄], Ph₂TlBr and NaBPh₄. The reaction of [Pt₂(μ-S)₂(PPh₃)₄] with PhTlBr₂ gave [Pt₂(μ-S)₂(PPh₃)₄TlBrPh]⁺, while reaction with TlBr₃ gave the dibromothallium(III) adduct [Pt₂(μ-S)₂(PPh₃)₄TlBr₂]⁺[TlBr₄]⁻. The latter complex is a rare example of a thallium(III) dihalide complex stabilised solely by sulfur donor ligands. X-ray crystal structure determinations on the complexes [Pt₂(μ-S)₂(PPh₃)₄TlPh₂]BPh₄, [Pt₂(μ-S)₂(PPh₃)₄TlBrPh]BPh₄ and [Pt₂(μ-S)₂(PPh₃)₄TlBr₂][TlBr₄] reveal a greater interaction between the thallium(III) centre and the two sulfide ligands on stepwise replacement of Ph by Br, as indicated by shorter Tl-S and Pt...Tl distances, and an increasing S-Tl-S bond angle. Investigations of the ESI MS fragmentation behaviour of the thallium(III) complexes are reported.

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  • Synthesis and characterisation of ferrocenyl-phosphonic and -arsonic

    Alley, Steven R.; Henderson, William (2001)

    Journal article
    University of Waikato

    The ferrocene-derived acids FcCH₂CH₂E(O)(OH)₂ [4, E=P; 10, E=As; Fc=Fe(η₅-C₅H₅)(η⁵-C₅H₄)] have been synthesized by the reaction of FcCH₂CH₂Br with either P(OEt)₃ followed by hydrolysis, or with sodium arsenite followed by acidification. Reaction of FcCH₂OH with (EtO)₂P(O)Na gave FcP(O)(OEt)(OH), which was converted to FcCH₂P(O)(OH)₂ (3) by silyl ester hydrolysis using Me₃SiBr–Et₃N followed by aqueous work-up. Similarly, the known phosphonic acid FcP(O)(OH)₂and the new derivatives 1,1′-Fc′[P(O)(OH)₂]₂ [Fc′=Fe(η⁵-C₅H₄)₂] and 1,1′-Fc′[CH₂P(O)(OH)₂]₂(7) have been synthesized via their corresponding esters. X-ray crystal structure determinations have been carried out on 3 and 7, and the hydrogen-bonding networks discussed. Electrospray mass spectrometry has been employed in the characterization of the various acids. Phosphonic acids give the expected [M–H]− ions and their fragmentation at elevated cone voltages has been found to be dependent on the acid. FcP(O)(OH)₂ fragments to [C₅H₄PO₂H]−, but in contrast Fc(CH₂)nP(O)(OH)₂ (n=1, 2) give Fe{η⁵-C₅H₄(CH₂)nP(O)O₂]− ions, which are proposed to have an intramolecular interaction between the Fe atom and the phosphonate group. In contrast, arsonic acid (10), together with PhAs(O)(OH)₂for comparison, undergo facile alkylation (in methanol or ethanol solvent), and at elevated cone voltages (e.g. >60 V) undergo carbon–arsenic bond cleavage giving [CpFeAs(O)(OR)O]− (R=H, Me, Et) and ultimately [AsO₂]− ions.

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  • Ligand exchange reactions of [Re₂(μ-OR)₃(CO)₆]⁻(R = H, Me) with sulfur, selenium, phosphorus and nitrogen donor ligands, investigated by electrospray mass spectrometry

    Jiang, Chenghua; Hor, T.S. Andy; Yan, Yaw Kai; Henderson, William; McCaffrey, Louise J. (2000)

    Journal article
    University of Waikato

    Negative-ion electrospray mass spectrometry has been used to investigate the reactions of the dinuclear rhenium aggregates [Re₂(μ-OH)₃(CO)₆]⁻ 1 and [Re₂(μ-OMe)₃(CO)₆]⁻ 2 with a range of thiols, benzeneselenol, and some other sulfur-, phosphorus- and nitrogen-based ligands. Typically up to three of the hydroxo ligands are replaced by simple thiolates, giving the series of species [Re₂(OH)₂(SR)(CO)₆]⁻, [Re₂(OH)(SR)₂(CO)₆]⁻, and [Re₂(SR)₃(CO)₆]⁻. Similarly, reaction of 1 with H₂S gives the species [Re₂(μ-SH)₃(CO)₆]⁻, which undergoes an analogous fragmentation process to [Re₂(μ-OH)₃(CO)₆]⁻, at high cone voltages, by loss of H₂S and formation of [Re₂(S)(SH)(CO)₆]⁻. With ligands which are good chelating agents (such as dithiocarbamates R₂NCS₂⁻, and thiosalicylic acid, HSC₆H₄CO₂H) initial substitution of one or two OH groups readily occurs, but on standing the dimer is cleaved giving [Re(S₂CNR₂)₂(CO)₃]⁻ and [Re(SC₆H₄CO₂)(CO)₃]⁻. The different reactivities of the dithiol reagents benzene-1,2- and benzene-1,4-dimethanethiol towards 1 are also described. Complex 1 also reacts with aniline, and with primary (but not secondary) amides RC(O)NH₂, giving monosubstituted species [Re₂(OH)₂(NHPh)(CO)₆]⁻ and [Re₂(OH)₂{NHC(O)R}(CO)₆]⁻ respectively. The reactions with adenine and thymine, and with the inorganic anions thiocyanate and thiosulfate, are also described.

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  • Mass spectrometry-directed synthesis of early–late sulfide-bridged heterobimetallic complexes from the metalloligand [Pt₂(PPh₃)₄(μ-S)₂] and oxo compounds of vanadium(V), molybdenum(VI) and uranium(VI)

    Fong, S.W. Audi; Yap, Woon Teck; Vittal, Jagadese J.; Henderson, William; Hor, T.S. Andy (2002)

    Journal article
    University of Waikato

    The metalloligand [Pt₂(PPh₃)₄(μ-S)₂] has been found to react with the transition metal oxo compounds, ammonium metavanadate, sodium molybdate, and the actinide complex uranyl nitrate to give sulfide-bridged heterobimetallic complexes [Pt₂(PPh₃)₄(μ₃-S)₂VO(OMe)₂]⁺, [Pt₂(PPh₃)₄(μ₃-S)₂MoO₂(OMe)]⁺, and [Pt₂(PPh₃)₄(μ₃-S)₂UO₂( ₂-NO₃)₂], respectively. Electrospray mass spectrometry (ESMS) was used to probe the reactivity of [Pt₂(PPh₃)₄(μ-S)₂] and thus identify likely targets for isolation and characterization. ESMS has also been used to investigate fragmentation pathways of the new species. No bimetallic species were detected with hydrated La(NO₃)₃or Th(NO₃)₄, or with the lanthanide shift reagent Eu(fod)₃ (fod = 6,6,7,7,8,8,8-heptafluoro-2,2-dimethyl-3,5-octanedionate). X-Ray crystal structure determinations have been carried out on [Pt₂(PPh₃)₄(μ₃-S)₂VO(OMe)₂]⁺, 2, (as its hexafluorophosphate salt) and [Pt₂(PPh₃)₄(μ₃-S)₂UO₂( ₂-NO₃)₂], 4. The vanadium atom of 2 has a distorted square pyramidal geometry, while the uranium in 4 has the expected linear dioxo coordination geometry, with two bidentate nitrates and a bidentate {Pt₂S₂} moiety.

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