135 results for 2000, Nicholson, Brian K., Journal article

  • New ruthenium carbonyl clusters containing unusual 5-sulfido-, 4-benzyne-, and thianthrene-derived ligands: Insertion of ruthenium into the thianthrene ring by C-S activation

    Hassan, Mohammad R.; Kabir, Shariff E.; Nicholson, Brian K.; Nordlander, Ebbe; Uddin, Md. Nazim (2007-07-01)

    Journal article
    University of Waikato

    Treatment of [Ru3(CO)12] with thianthrene in refluxing toluene afforded [( 4-S)Ru4( -CO)2(CO)9( 4- 2-C6H4)] (1), [( 5-S)Ru6( -CO)2(CO)15( - 3-C12H8S)] (2), and [( 5-S)Ru5( -CO)2(CO)11( - 3-C12H8S)( 4- 2-C6H4)] (3) in 18%, 8%, and 16% yields, respectively. Thermolysis of 2 in refluxing heptane gave compounds 1 and 3. A similar thermolysis of 3 in refluxing toluene gave 1 in 90% yield. Treatment of 3 with neat MeCN afforded the labile compound [( 5-S)Ru5( -CO)2(CO)10( - 3-C12H8S)( 4- 2-C6H4)(MeCN)] (4) in 73% yield. The reaction of 4 with P(OMe)3 gave the substitution product [( 5-S)Ru5( -CO)2(CO)10( - 3-C12H8S)( 4- 2-C6H4){P(OMe)3}] (5) in 52% yield. Compounds 1-4 have been structurally characterized. Compound 1 contains a 4-capping sulfido and a 4- 2-benzyne ligand, whereas 3, 4, and 5 contain 5-sulfido and 4- 2-benzyne ligands. The latter three compounds provide rare examples of 5-sulfido and metal-assisted opening of the thianthrene ligand on polynuclear centers. In compounds 1, 3, and 4 the 4- 2-benzyne ligand is perpendicular to the Ru4 face of the clusters and represents a previously uncharacterized bonding mode for benzyne.

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  • β-Cyclomanganated 1,5-diphenylpenta-1,4-dien-3-ones and their reactions with alkynes: routes to η5-pyranyl--- and η5-oxocycloheptadienyl---Mn(CO)3 complexes

    Tully, Warren; Main, Lyndsay; Nicholson, Brian K. (2001-08-01)

    Journal article
    University of Waikato

    1,5-Diphenylpenta-1,4-dien-3-ones (4) are cyclometalated with benzylpentacarbonylmanganese to form [[1-phenyl-2-((E)-3-phenylprop-2-en-1-oyl-κO)]ethenyl-κC1]tetracarbonylmanganese derivatives (5). Coupling of 5 with alkynes in some cases gives [4-phenyl-2-(2-phenylethenyl)pyranyl-η5]tricarbonylmanganese complexes (6) analogous to those previously reported for β-manganated chalcones, but in other cases an alternative cyclisation pathway subsequent to insertion of alkyne into the C---Mn bond leads to [6-oxo-4,7-diphenylcyclohepta-1,4-dienyl-1,2,3,4,5-η]tricarbonylmanganese complexes (7). The X-ray crystal structure determination is reported for one such compound, [6-oxo-2,4,7-triphenylcyclohepta-1,4-dienyl-1,2,3,4,5-η]tricarbonylmanganese (7a), derived from 1,5-diphenylpenta-1,4-dien-3-one and phenylacetylene. The 7-phenyl group is found to occupy the endo position, and a mechanism involving Mn-mediated aryl migration is suggested to explain this stereochemistry. The reaction of 7a with ammonium cerium(IV) nitrate gives a low yield of 2-nitro-3,5,7-triphenylcyclohepta-2,4,6-trien-1-one (9), whose structure was established by X-ray crystal structure analysis. The pyranyl complexes (6) provide the corresponding pyrylium triiodide salts (8) when demetalated with iodine.

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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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  • Five-coordinate gold(III) complexes of the Kläui ligands [(η⁵-C₅H₅)Co{P(O)(OR)₂}₃]− (R°=°Me, Et)

    Kilpin, Kelly Joan; Henderson, William; Nicholson, Brian K. (2009)

    Journal article
    University of Waikato

    The reactions of cycloaurated gold(III) dichloride complexes [LAuCl₂] (L°=°2-C₆H₄CH₂NMe₂ or 2-C₆H₄PPh₂ NPh) with monoanionic tripodal oxygen donor Kläui ligands [(η⁵-C₅H₅)Co{P(O)(OR) ₂}₃]− (R°=°Me or Et) results in the formation of cationic gold(III) salts [LAu{OP(OR) ₂}₃Co(η⁵-C₅H₅)]+. An X-ray structure determination on [(2-C₆H₄PPh₂ NPh)Au{OP(OR) ₂}₃Co(η⁵-C₅H₅)]BF₄shows that the Kläui ligand coordinates strongly to the gold through two oxygen atoms, and weakly through the third, giving the gold(III) a distorted square pyramidal geometry. This is the first structurally characterised example of this geometry for gold(III) with ligands other than those containing rigid bipyridine or phenanthroline backbones. In solution at room temperature there is rapid interchange (on the NMR timescale) between the oxygen atoms of the Kläui ligands, which is frozen out on cooling.

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  • Synthesis and characterisation of [Pt₂(μ-S)(μ-I)(PPh₃)₄]⁺ – A cationic iodo analogue of the metalloligand [Pt₂(μ-S)₂(PPh₃)₄]

    Fong, S.W. Audi; Evans, Kim; Henderson, William; Nicholson, Brian K.; Hor, T.S. Andy (2009)

    Journal article
    University of Waikato

    Reaction of [Pt₂(μ-S)₂(PPh₃)₄] with a number of transition metal–iodo complexes leads to the formation of the cationic iodo analogue [Pt₂(μ-S)(μ-I)(PPh₃)₄]⁺, identified using electrospray ionisation mass spectrometry (ESI MS). Synthetic routes to this complex were developed, using the reaction of [Pt₂(μ-S)₂(PPh₃)₄] with either [PtI₂(PPh₃)₂] or elemental iodine. The complex was characterised by NMR spectroscopy, ESI MS and an X-ray structure determination, which reveals the presence of a planar, disordered {Pt₂SI}⁺ core. Monitoring the iodine reaction by ESI MS allows the identification of various iodine species, including the short-lived intermediate [Pt₂(μ-S)₂(PPh₃)₄I]⁺, which allows a mechanism for the reaction to be proposed.

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  • Influence of chain length on mono- versus di-alkylation in the reactivity of [Pt₂(μ-S)₂(PPh₃)₄] towards α,ω-dihalo-n-alkanes; a synthetic route to platinum(II) ω-haloalkylthiolate complexes

    Devoy, Sarah M.; Henderson, William; Nicholson, Brian K.; Hor, T.S. Andy (2010)

    Journal article
    University of Waikato

    The reactions of [Pt₂(μ-S)₂(PPh₃)₄] with a,x-dibromoalkanes Br(CH₂)nBr (n = 4, 5, 6, 8, 12) gave monoalkylated [Pt₂(μ-S){μ-S(CH₂)nBr}(PPh₃)₄]⁺ and/or di-alkylated [Pt₂(μ-S(CH₂)nS}(PPh₃)₄]²⁺ products, depending on the alkyl chain length and the reaction conditions. With longer chains (n = 8, 12), intramolecular di-alkylation does not proceed in refluxing methanol, with the mono-alkylated products [Pt₂ (μ-S){μ-S(CH₂)nBr}(PPh₃)₄]⁺ being the dominant products when excess alkylating agent is used. The bridged complex [{Pt₂(μ-S)₂(PPh₃)₄}₂{μ-(CH₂)12}]²⁺ was accessible from the reaction of [Pt₂ (μ-S)₂(PPh₃)₄] with 0.5 mol equivalents of Br(CH₂)12Br. [Pt₂(μ-S){μ-S(CH₂)₄Br}(PPh₃)₄]⁺ can be cleanly isolated as its BPh₄⁻ salt, but undergoes facile intramolecular di-alkylation at -18 degree C, giving the known species [Pt₂(μ-S(CH₂)₄S}(PPh₃)₄]²⁺. The reaction of I(CH₂)₆I with [Pt₂(μ-S)₂(PPh₃)₄] similarly gives [Pt₂ (μ-S){μ-S(CH₂)₆I}(PPh₃)₄]⁺, which is fairly stable towards intramolecular di-alkylation once isolated. These reactions provide a facile route to x-haloalkylthiolate complexes which are poorly defined in the literature. X-ray crystal structures of [Pt₂(μ-S){μ-S(CH₂)₅Br}(PPh₃)₄]BPh₄ and [Pt₂(μ-S(CH₂)₅S} (PPh₃)₄](BPh₄)₂ are reported, together with a study of these complexes by electrospray ionisation mass spectrometry. All complexes fragment by dissociation of PPh₃ ligands, and the bromoalkylthiolate complexes show additional fragment ions [Pt₂(μ-S){μ-S(CH₂)n_2CH=CH₂}(PPh₃)m]⁺ (m = 2 or 3; m – 4), most significant for n = 4, formed by elimination of HBr.

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  • Cycloaurated triphenylphosphine-sulfide and –selenide

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

    Journal article
    University of Waikato

    The first examples of cycloaurated phosphine sulfides and triphenylphosphine selenide have been synthesised; these complexes are fairly rare examples of gold(III) complexes with potentially reducing sulfur- and selenium-donor ligands. The cycloaurated complex (AuCl₂ (2-C₆H₄P(S)Ph₂) was synthesised in good yield by transmetallation of the organomercury precursor Hg(2-C₆H₄P(S)Ph₂)₂ with Me₄N[AuCl₄]. A route to the chloro-mercury analogue ClHg(2-C₆H₄P(S)Ph₂) was developed by reaction of the cyclomanganated triphenylphosphine sulfide (CO)₄Mn(2-C₆H₄P(S)Ph₂) with HgCl₂; this mercury substrate was also used in the synthesis of AuCl₂(2-C₆H₄P(S)Ph₂). The cycloaurated triphenylphosphine selenide complex AuCl₂(2-C₆H₄P(Se)Ph₂) was synthesised by an analogous methodology using the new phosphine selenide Hg(2-C₆H₄P(Se)Ph₂)₂ [prepared from Hg(2-C₆H₄PPh₂)₂ and elemental Se under sonication]. The phosphonamidic analogue AuCl₂(2-C₆H₄P(S)(Net₂)₂) has also been synthesised from PhP(S)(Net₂)₂via lithiation and mercuration. X-Ray crystal structures of several compounds are reported, and show the presence of puckered ring systems.

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  • Two complexes containing 19-atom chains linking metal centres

    Bruce, Michael I.; Nicholson, Brian K.; Zaitseva, Natasha N. (2009)

    Journal article
    University of Waikato

    The first example of a complex containing a C₁₉ chain, {Co₃(μ-dppm)(CO)₇}{μ₃-C(C≡C)₉}{W(CO)₃Cp}, has been prepared in 22% yield from the Pd(0) / Cu(I)-catalysed reaction between I(C≡C)₃I, W{C≡CC≡CAu(PPh₃)}(CO)₃Cp and Co₃{μ₃-C(C≡C)₄Au(PPh₃)}(μ-dppm)(CO)₇. Other products also formed include {Co₃(μ-dppm)(CO)₇}{μ₃-C(C≡C)₆}{W(CO)₃Cp} (32%), {Co₃(μ-dppm)(CO)₇}₂{μ₃:μ₃-C(C≡C)xC} [x = 8 (6%) and 11 (5%)], containing respectively C₁₃, C₁₈ and C₂₄ chains, and {W(CO)₃Cp}₂{μ-(C≡C)x} (x = 4, 7) (traces). A second example of a 19-atom chain is found in Hg{(C≡C)₄C[Co₃(μ-dppm)(CO)₇]}₂, obtained in 24% yield from the reaction between Hg(OAc)₂ and Co₃{μ₃-C(C≡C)₄SiMe₃}(μ-dppm)(CO)₇ in the presence of NaOMe.

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  • A Percyanovinylidene−Ruthenium Complex, Ru{═C═C₅(CN)₃[═C(CN)₂]₂}(dppe)Cp*

    Bruce, Michael I.; Morris, Jonathan C.; Nicholson, Brian K.; Skelton, Brian W.; White, Allan H.; Zaitseva, Natasha N. (2011)

    Journal article
    University of Waikato

    The reaction between Ru(C≡CC≡CAg)(dppe)Cp* and tcne affords a novel percyanovinylidene complex by an unusual decyano-dimerization reaction of the cyanocarbon with the diynyl fragment. This complex is also obtained from tcne and Ru{C≡CC≡C[Au(PPh₃)]}(dppe)Cp*, together with Ru{C≡CC[═C(CN)₂]C[Au(PPh₃)]═C(CN)₂}(dppe)Cp*, formed by the anticipated [2 + 2] cycloaddition and subsequent ring-opening reactions.

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  • Synthesis and characterization of nickel(II) maltolate complexes containing ancillary bisphosphine ligands

    Alblawi, Jamal; Henderson, William; Nicholson, Brian K. (2011)

    Journal article
    University of Waikato

    Cationic nickel(II) complexes containing chelating O,O'-donor maltolate or ethyl maltolate ligands in conjunction with bidentate bisphosphine ligands Ph₂P(CH₂)nPPh₂ were prepared by a one-pot reaction starting from nickel(II) acetate, bisphosphine, maltol (or ethyl maltol), and trimethylamine, and isolated as their tetraphenylborate salts. An X-ray structure determination of [Ni(maltolate)(Ph₂PCH₂CH₂PPh₂)]BPh₄ shows that the maltolate ligand binds asymmetrically to the (slightly distorted) square-planar nickel(II) center. The simplicity of the synthetic method was extended to the synthesis of the known platinum(II) maltolate complex [Pt(maltolate)(PPh₃)₂]BPh₄ which was obtained in high purity.

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  • Syntheses and structural studies of several diynyl-ruthenium complexes and their adducts with cyano-alkenes

    Bruce, Michael I.; Burgun, Alexandre; Grelaud, Guillaume; Jevric, Martyn; Nicholson, Brian K.; Skelton, Brian W.; White, Allan H.; Zaitseva, Natasha N. (2011)

    Journal article
    University of Waikato

    Herein are described some continuing investigations into the reactions of cyano-alkenes with diynyl-ruthenium complexes which have resulted in the preparation and characterisation of diynyl-ruthenium compounds Ru(C≡CC≡CR)(PP)Cp [R = Ph, PP = dppe; R = Fc, PP = dppf; R = CPh=CBr₂, PP = (PPh₃)₂], together with the polycyanobutadienyls Ru{C≡CC[=C(CN) ₂]CR=CR′(CN)}(PP)Cp′ [R = Fc, (PP)Cp′ = (dppf)Cp; R = H, SiMe₃, (PP)Cp′ = (dppe)Cp*] formed by [2 + 2]-cycloaddition of the cyano-alkenes to the outer C≡C triple bonds and subsequent ring-opening reactions. Single-crystal XRD molecular structure determinations of six complexes are reported.

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  • New Sb₁₂ and Sb₁₄ Polyoxometalate Frameworks Derived from Arylstibonic Acids: [LiH₃(p-MeC₆H₄Sb)₁₂O₂₈]⁴⁻ and [BaH₁₀(p-MeC₆H₄Sb)₁₄O₃₄]

    Nicholson, Brian K.; Clark, Christopher J.; Wright, Cody Elvin; Telfers, Shane G.; Groutso, Tania (2011)

    Journal article
    University of Waikato

    The lithium salt of p-tolylstibonic acid contains the anion [LiH₃(p-MeC₆H₄Sb)₁₂O₂₈]⁴⁻, in which the Li⁺ is fully enclosed within an {Sb₁₂O₂₈} cage with γ Keggin ion geometry; the idealized overall formula is Li₅[LiH₃(p-MeC₆H₄Sb)₁₂O₂₈]Br•18H₂O. In contrast, Ba²⁺ induces the formation of the unprecedented {Sb₁₄O₃₄} bowl-shaped polyoxostibonate [BaH₁₀(p-MeC₆H₄Sb)₁₄O₃₄]•4H₂O. Compounds were characterized by single-crystal X-ray crystallography and by ESI-MS.

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  • Substitution of Tetracyanoethene by Ethynyl–Metal Complexes Gives Tricyanovinylethynyl (Tricyanobutenynyl) Derivatives: Syntheses, Protonation, and Addition of Metal–Ligand Fragments

    Bruce, Michael I.; Fox, Mark A.; Low, Paul J.; Nicholson, Brian K.; Parker, Christian R.; Patalinghug, Wyona C.; Skelton, Brian W.; White, Allan H. (2011)

    Journal article
    University of Waikato

    A series of complexes containing the new tricyanovinylethynyl (3,4,4-tricyanobut-3-en-1-ynyl) ligand have been obtained by substitution of a CN group in tetracyanoethene upon reaction with the ethynyl complexes M(C≡CH)(PP)Cp′ (M = Ru, Os, (PP)Cp′ = (PPh3)2Cp; M = Ru, PP = dppe, Cp′ = Cp, Cp*). The reactions proceed in higher yield as the metal environment becomes more sterically hindered, the normal [2 + 2]-cycloaddition/ring-opened product M{C[═C(CN)₂]CH═C(CN)₂}(PP)Cp′ also being formed in some cases. The diynyl complex Ru(C≡CC≡CH)(dppe)Cp* reacts with tcne to give only the ring-opened adduct Ru{C≡CC[═C(CN)₂]CH═C(CN)₂}(dppe)Cp*. Protonation (HBF₄ or HPF₆) of Ru{C≡CC(CN)═C(CN)₂}(dppe)Cp* afforded the vinylidene cation [Ru{═C═CHC(CN)═C(CN)₂}(dppe)Cp*]⁺. A second transition-metal fragment MLn (MLn = Ru(PPh₃)₂Cp, M′(dppe)Cp* (M′ = Ru, Os), RuCl(dppe)₂) can be added to the CN group trans to the metal center; electrochemical, spectroscopic, and computational studies indicate that there is little ground-state delocalization between the metal centers. In the case of the tricyanovinylethynyl derivatives, an intense MLCT (or ML—LCT) transition can be identified in the visible region, which is responsible for the intense blue to purple color of these species; the analogous transition in the vinylidene-based complexes is significantly blue-shifted. The X-ray crystallographically determined structures of several of these complexes are reported. The cations [{Cp*(dppe)Ru}{μ-(C/N)≡CC(CN)═C(CN)(≡C/N)}{M(dppe)Cp*}]⁺ (M = Ru, Os) show some C≡C/C≡N disorder (and associated Ru/Os disorder in the case of the heterometallic example) in the crystals.

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  • Synthesis and characterization of new trimetallic complexes with {Pt₂Au(μ-S) ₂} ⁿ⁺ (n=2, 3) cores containing C, N and N, N donor ligands

    White, Bradley C.; Henderson, William; Hor, T.S. Andy; Nicholson, Brian K. (2013)

    Journal article
    University of Waikato

    Reactions of the dinuclear platinum(II) sulfide complex [Pt ₂(μ-S) ₂(PPh ₃) ₄] with a range of gold(III) dichloride complexes [AuLCl ₂] containing C, N- or N, N-cycloaurated ligands L gives a new series of dicationic adducts [Pt ₂(μ-S) ₂(PPh ₃) ₄AuL] ²⁺, isolated as their PF ₆ - salts. The complexes investigated are [Au{C₆₋H ₄(CH ₂NMe ₂)-2}Cl ₂], [Au{C ₆H ₃(CH ₂NMe ₂)-2-(OMe)-5}Cl ₂], [Au{NC ₅H ₄(CH ₂C ₆H ₄)-2}Cl ₂], [Au{NC ₅H ₄(COC ₆H ₄)-2}Cl ₂] and [Au{NC ₅H ₄(CONH)-2}Cl ₂]. An X-ray structure determination on the picolinamide-derived complex [Pt ₂(μ-S) ₂(PPh ₃) ₄Au{NC ₅H ₄(CONH)-2}](PF₆) ₂ was not of sufficiently high quality for detailed discussion, but confirmed the atom connectivity. Reactions of [Pt ₂(μ-S) ₂(PPh ₃) ₄] with [AuCl ₂(bipy)]PF ₆ (L=bipy=2,2'-bipyridine) and [AuCl ₂(phen)]Cl (L=phen=1,10-phenanthroline) gives the corresponding tricationic adducts [Pt ₂(μ-S) ₂(PPh ₃) ₄AuL] ³⁺, also isolated as their PF ₆⁻ salts. The complexes are characterised by NMR spectroscopy, electrospray mass spectrometry and microelemental analyses. Biological assay data of a selection of these new complexes towards the P388 murine leukemia cell line, as well as a range of antimicrobial tests, reveals overall low activity compared to other cycloaurated gold(III) complexes.

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  • A novel structural rearrangement reaction of dialkylated derivatives of [Pt ₂ (μ-S) ₂ (PPh ₃) ₄] involving Pt-C bond formation

    Ujam, Oguejiofo Theophilus; Devoy, Sarah M.; Henderson, William; Nicholson, Brian K.; Hor, T.S. Andy (2012)

    Journal article
    University of Waikato

    Reaction of [Pt ₂ (μ-S) ₂ (PPh ₃) ₄] with the dialkylating agents ClCH ₂ C(O)CH ₂ Cl or ClCH ₂ C(NNHC(O)NH ₂)CH ₂ Cl gives the dicationic di-μ-thiolate complexes [Pt ₂ {μ-SCH ₂ C(O)CH ₂ S)(PPh ₃) ₄] ²⁺ or [Pt ₂ {μ-SCH ₂ C(NNHC(O)NH ₂)CH ₂ S} (PPh ₃) ₄] ²⁺, isolated as BPh ₄ ⁻ salts and characterised by ESI mass spectrometry, NMR spectroscopy and single-crystal X-ray crystallography. Treatment of the complex [Pt 2{μ-SCH 2C(O)CH 2S)(PPh₃) ₄] ²⁺, which contains a [6.6.4] bicyclic system, with hydroxide ions results in deprotonation of a CH 2 group and rearrangement of the resulting monocation, giving [Pt ₂ (μ-SCH ₂ C(O)CHS}(PPh ₃) ₄] ⁺, isolated as its PF ₆ ⁻ salt. An X-ray structure determination shows the complex to have a novel rearranged [6.5.5] bicyclic system containing a Pt-S-Pt-S-C five-membered ring with a Pt-C bond. The alkyl ligand has a high trans-influence, manifest in a long trans Pt-P bond and small 1J(PtP) coupling constant to the trans PPh 3 ligand. Reaction of [Pt ₂ (μ-S) ₂ (PPh ₃) ₄] with the 2,4-dinitrophenylhydrazone derivative of 1,3-dichloroacetone leads to the closely related complex [Pt ₂ {μ-SCH ₂ C(NNHAr)CHS} (PPh ₃) ₃Cl] [Ar = C ₆H ₃ (NO ₂) ₂] in which a PPh ₃ ligand is substituted by a chloride.

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  • Synthesis and structure of a dimeric, anionic thioglycolate derivative of manganese carbonyl

    Dai, Yuan; Nicholson, Brian K. (2012)

    Journal article
    University of Waikato

    The thioglycolate anion reacts with BrMn(CO)5 to form a dimeric complex with bridging sulfur atoms of formula [Mn ₂(thioglycolate) ₂ (CO) ₆] ²⁻. This was isolated as the Et ₃NH ⁺ salt and fully characterized for comparison with the previously reported thiosalicylate analogue.

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  • Novel polyoxometalates: Is antimony the new molybdenum?

    Nicholson, Brian K.; Clark, Christopher J. (2012)

    Journal article
    University of Waikato

    Polyoxometalates based on Mo, W or V have been known for a long time and present a diverse range of structures, with the [XMo₁₂O₄₀]ⁿ⁻ Keggin ions (X = P, Si ,…) perhaps the best known.¹ They are still subject to intense research with >4000 papers published in the past five years. Following on from our study² of aryl arsonic acids RAsO₃H₂, which are straightforward molecular species based on four-coordinate As(V), we became interested in the corresponding antimony compounds. Although aryl stibonic acids of nominal formula RSbO₃H₂ have been known for over 100 years,³ their composition has remained uncertain, as they form only amorphous solids, have complicated titration behaviour and only limited solubility. The presumption has been that they are polymeric, based on 5- or 6-coordinate Sb with Sb-O-Sb linkages, though direct evidence is sparse.⁴ Recently, it has been shown by Beckman that if very bulky R groups are used, then relatively simple dimers such as (2,6-Mes₂C₆H₃Sb₂O₂(OH)₄(Mes=mesityl) can be isolated, but these represent a special case.⁵

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  • Isopolyoxometalates derived from arylstibonic acids with "reverse-Keggin ion" structures based on [M(RSb) ₁₂O ₂₈] cores, M = Co(ii) or Zn(ii).

    Nicholson, Brian K.; Clark, Christopher J.; Telfer, Shane G.; Groutso, Tania (2012)

    Journal article
    University of Waikato

    The preparations and structures are described of four new polyoxostibonates, [Co(p-MeC ₆H ₄Sb) ₁₂O ₂₈{Co(H ₂O) ₃} ₄]Cl ₂₋ 6H ₂O, [Co(p-ClC ₆H ₄Sb)₁₂O ₂₈{Co(H ₂O) ₃} ₄]Cl₂₋ 22H ₂O, (PhCH ₂NMe ₃) ₂[Zn(p-ClC ₆H ₄Sb) ₁₂O ₂₈Zn ₄Cl₂•₅₄ Br ₁•₄₆]•8MeCN•H ₂O and [BaCoH ₄(p-MeC ₆H ₄Sb)O ₂₈] •5H₂O. Each of these has a framework of 12 (RSb) groups linked by 28 O atoms, with one transition metal ion in a tetrahedral site in the centre. Other metal ions are coordinated to the polyhedral faces. Three of the complexes have the ε Keggin ion geometry, while the fourth is a δ isomer.

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  • Crystal structure models for the Aldaramide Units of Poly(pentaramides)

    Hinton, Michael R.; Nicholson, Brian K.; Manley-Harris, Merilyn; Hardcastle, Kenneth I.; Kiely, Donald E. (2013)

    Journal article
    University of Waikato

    The X-ray crystal structures of seven structurally related diamides, N,N′-dihexyl- and N,N′-dimethylglutaramide, N,N′-dimethylxylaramide, N,N′-dimethyl-l-arabinaramide, N,N′-dimethylribaramide monohydrate, 2,3,4-tri-O-acetyl-N,N′-dimethylxylaramide, and 2,3,4-tri-O-acetyl-N,N′-dimethyl-l-arabinaramide, were determined. These diamides were chosen as solid-state conformational models for the diamido repeating units of the corresponding polyamides. Solid-state conformations of the two N,N-dialkyglutaramides, with no pendant groups, were compared to those of their stereochemically different trihydroxy derivatives N,N′-dimethylxylaramide, l-arabinaramide and ribaramide, and the two aforementioned tri-O-acetylpentaramides.

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  • A zwitterionic monoalkylated derivative of [Pt₂(μ-S)₂(PPh₃)₄] from 1,3-propanesultone

    Ujam, Oguejiofo Theophilus; Henderson, William; Nicholson, Brian K. (2013)

    Journal article
    University of Waikato

    Reaction of dinuclear platinum(II) sulfido complex [Pt₂(μ-S)₂(PPh₃)₄] with 1,3-propanesultone gives the novel zwitterionic monoalkylated thiolate complex [Pt₂(μ-S){μ-S(CH₂)₃SO₃}•(PPh₃)₄], which was characterized by NMR spectroscopy, electrospray ionisation mass spectrometry, and a single crystal X-ray structure determination. Crystals are monoclinic, space group P2(1)/c with unit cell dimensions a = 16.8957(3) Å, b = 15.5031(3) Å, c = 28.0121(5) Å, β = 99.780(1)°, for Z = 4.

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