142 results for 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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  • 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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  • Cluster Chemistry : XVII.Radical ion-initiated synthesis of ruthenium cluster carbonyls containing tertiary phosphines, phosphites, arsines, SbPh₃, or isocyanides

    Bruce, Michael I.; Matisons, Janis G.; Nicholson, Brian K. (1983)

    Journal article
    University of Waikato

    The syntheses of over sixty known and new derivatives of Ru₃(CO)₁₂ and H₄Ru₄(CO)₁₂ by substitution reactions initiated by sodium diphenylketyl are described. The range of ligands studied includes isocyanides, tertiary phosphines and phosphites, tertiary arsines and SbPh₃. The reactions are characterised by high degrees of specificity and conversion: under mild conditions up to four ligands can be introduced. Comparisons with the corresponding thermally induced reactions are made in several cases. The reactions provide routes to mixed ligand derivatives of the cluster carbonyls, although account of relative Lewis base strengths of the ligands may have to be taken. Possible mechanisms of these reactions are discussed briefly, as are the IR ν (CO) spectra of the Ru₃ (CO)12-nLn complexes.

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  • Preparation and the crystal and molecular structure of [Net₄][Ge{Co₂(CO)₇}{Co₂(CO)₆[HgCo(CO)₄]}]: an anion containing a mercury-bridged cobalt–cobalt bond

    Duffy, D. Neil; Mackay, Kenneth M.; Nicholson, Brian K.; Robinson, Ward T. (1981)

    Journal article
    University of Waikato

    The title compound has been isolated from the reaction of Gel4 with Na[Co(CO)₄] in the presence of Hg and has been characterised by X-ray analysis. Crystals are triclinic, a= 12.065(1), b= 17.334(2), c= 9.222(1)Å, α= 95.17(3), β= 82.72(3), γ= 96.95(3)°, space group P , and Z= 2. The structure has been solved by direct methods and refined to R= 0.049 for 3 136 reflections [I 5σ(I)]. The anion contains a common Ge atom bridging the Co–Co bonds both of a Co₂(CO)₇ unit and of a Co₂(CO)₆ unit which is also bridged by a HgCo(CO)₄ group.

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  • Transition metal carbonyl derivatives of the germanes: XIV. Studies of mixed cobalt carbonyl/manganese carbonyl substituted germanes including [(CO)₅MnGeCo₃(CO)₉], μ₃-(pentacarbonylmanganesegermylidyne)cyclotris(tricarbonylcobalt)(3Co---Co)

    Christie, Judy A.; Duffy, D. Neil; Mackay, Kenneth M.; Nicholson, Brian K. (1982)

    Journal article
    University of Waikato

    [Mn(CO)₅GeH₃] reacts smoothly with Co₂(CO)₈ to form the [(CO)₅MnGeCo₃(CO)₉], which is also produced by the reaction of Mn(CO)₅⁻ with [(CO)₄CoGeCo₃(CO)₉]. [Mn(CO)₅GeMeH₂] similarly reacts with Co₂(CO)₈ to give [{Mn(CO)₅} {Co₂(CO)₇}GeMe]. The products were characterised spectroscopically and the ESR spectrum of the radical ion of the title compound is presented.

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  • Anionic germanium polycobalt carbonyl clusters. Part 3. Preparation and structures of [Net₄][Ge₂Co₇(CO)₂₁] and [Net₄][Ge{Co₇(CO)₂₀}]; two large clusters incorporating tetrahedral GeCo₃ units

    Duffy, D. Neil; Mackay, Kenneth M.; Nicholson, Brian K.; Thomson, Ralph A. (1982)

    Journal article
    University of Waikato

    Reactions of the [Ge{Co₅(CO)₁₆}]⁻ cluster have given rise to two new germanium–polycobalt cluster anions, characterised as their Net₄⁺ salts by X-ray crystallography. The complex [NEt₄][Ge₂Co₇(CO)₂₁](1a) forms triclinic crystals, space group P , with a= 13.085(2), b= 19.712(7). c= 12.220(8)Å, α= 109.10(3), β= 92.60(2), γ= 129.32(3)°, and Z= 2. The structure was solved by direct methods and refined to R=R′= 0.046 for 2 076 reflections with l > 3σ(l). The anion (1) consists of two –GeCo₃(CO)₉ units bonded mutually trans about a trigonal planar Co(CO)₃ group, giving idealised C3v, symmetry. For [Net₄][Ge{Co₇(CO)₂₀}](2a). crystals are monoclinic, space group P21/c, with a= l2.761(7), b= 18.415(3), c= 17.675(4)Å, β= 102.91(3)°, and Z= 4. The structure was refined to R= 0.077, R′= 0.074, for 1 123 reflections with I > 2σ(I). The anion (2) is a derivative of the C3v structure of [Co₄(CO)₁₂] with the axial carbonyl ligand of one basal cobalt replaced by a –GeCo₃-(CO)₉⁻ fragment. The Co4 tetrahedron is disordered.

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  • Anionic germanium polycobalt carbonyl clusters. Part 2. Preparation and structure of [Net₄][Ge{Co₅(CO)₁₆}], a cluster which contains five-co-ordinate germanium

    Croft, Rex A.; Duffy, D. Neil; Nicholson, Brian K. (1982)

    Journal article
    University of Waikato

    Addition of [Co(CO)₄]⁻ to [Ge{Co₄(CO)n}](n= 16, 14, or 13) under mild conditions gives good yields of [Ge{Co₅(CO)₁₆}]⁻. This forms crystals with Net₄⁺ which are orthorhombic, space group Pn2₁ a with a= 12.014(1), b= 36.938(4), c= 15.249(2), and Z= 8. The crystal structure was solved by direct methods and refined, with some difficulty due to pseudo-symmetry, to R= 0.088, R′= 0.081, for 1 590 unique reflections with F² > 2σ(F²). The anion has a GeCo₅ metal skeleton consisting of a GeCo₂ triangle and a GeCo₃ tetrahedron sharing a common apex at Ge. The five Ge–Co bond lengths vary from 2.33 to 2.51 Å. Three of the CO ligands on the GeCo₃ unit bridge the three Co–Co bonds, with two terminal CO groups on each Co atom. On the GeCo₂ moiety there are six terminal and one bridging carbonyls.

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  • Transition-metal carbonyl derivatives of the germanes. Part 13. Preparation, spectroscopic properties, and the crystal and molecular structure of bis[µ-carbonyl-bis(tricarbonylcobaltio)(Co–Co)]germanium (4Co–Ge), [Ge{Co₂(CO)₇}₂]; a new type of group 4–tetracobalt species

    Gerlach, Robert F.; Mackay, Kenneth M.; Nicholson, Brian K.; Robinson, Ward T. (1981)

    Journal article
    University of Waikato

    Reaction between Gel₄ and [Co(CO)₄]⁻ or between GeH₄ and [Co₂(CO)₈] gives [Ge{Co₂(CO)₇}₂](1). The crystal and molecular structure of (1) has been obtained by X-ray methods. Crystals are triclinic, with a= 10.396(2), b= 16.495(3), c= 12.879(2)Å, α= 90.33(2), β= 97.68(2), γ= 95.03(2)°, space group P1, and Z= 4. The structure was solved by direct methods and refined by least-squares techniques to R= 0.056 for 2 852 reflections [I 5σ(l)]. The molecule exhibits approximate C₂ symmetry with the Ge atom bridging the Co–Co bonds of two Co₂(CO)₇ units. The Ge bridge is unsymmetric with unequal Ge–Co bond lengths (average 2.38, 2.34 Å); the corresponding µ-CO in each unit is asymmetrically disposed in the opposite sense. Infrared and mass spectral data for [Ge{Co₂(CO)₇}₂] are also discussed.

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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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  • Orthomercurated and cycloaurated derivatives of the iminophosphorane Ph3P NPh

    Brown, Samuel D.J.; Henderson, William; Kilpin, Kelly Joan; Nicholson, Brian K. (2007-03-01)

    Journal article
    University of Waikato

    Ortho-lithiation of Ph3P NPh followed by reaction with HgCl2 gave good yields of [Hg{C6H4(PPh2 NPh)-2}Cl], 3, which was characterised spectroscopically and by an X-ray crystal structure determination. This is an isomer of the product of direct mercuration of Ph3P NPh which occurs on the N-bonded phenyl ring [J. Vicente, J.A. Abad, R. Clemente, J. Lopez-Serrano, M.C. Ramirez de Arellano, P.G. Jones, D. Bautista, Organometallics, 22 (2003) 4248]. Transmetallation of 3 with [AuCl4]− gave the corresponding cycloaurated complex [Au{κ2-C,N-C6H4(PPh2 NPh)-2}Cl2], with a five-membered metallocyclic ring incorporating four different elements.

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  • The pterocellins: novel bioactive alkaloids from the marine Bryozoan Ptrerocella vesiculosa

    Yao, Biao; Prinsep, Michèle R.; Nicholson, Brian K.; Gordon, Dennis P. (2003-01-01)

    Journal article
    University of Waikato

    Two new alkaloids, pterocellins A and B, have been isolated from the New Zealand marine bryozoan Pterocella vesiculosa. Structural elucidation was achieved through NMR and mass spectral analysis in conjunction with a single-crystal X-ray diffraction study of pterocellin A. The pterocellins possess a novel heterocyclic skeleton and exhibit potent antitumor activity and antimicrobial activity in vitro but only modest activity in the in vivo hollow fiber assay at the National Cancer Institute.

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  • The composition of Ehrlich's salvarsan: Resolution of a century-old debate

    Lloyd, Nicholas C.; Morgan, Hugh W.; Nicholson, Brian K.; Ronimus, Ron S. (2004-08-01)

    Journal article
    University of Waikato

    Ehrlich introduced in 1910 the compound 3-amino-4-hydroxyphenylarsenic(I) [Salvarsan, arsphenamine, Ehrlich 606,] as a remedy for syphilis, a disease caused by the spirochaete bacterium Treponema pallidum. His methodical search for a specific curative for an identified disease can be regarded as the introduction of targeted chemotherapy.

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  • Coordination isomerism in salicylhydroxamate complexes of platinum(II) and palladium(II)

    Henderson, William; Evans, Cameron; Nicholson, Brian K.; Fawcett, John (2003-01-01)

    Journal article
    University of Waikato

    The syntheses of a range of platinum(II) and palladium(II) complexes containing salicylhydroxamate ligands are described. The ancillary ligands, together with the synthetic route, influence the coordination mode of the salicylhydroxamate ligand. Reaction of cis-[PtCl₂(PPh₃)₂] with salicylhydroxamic acid and trimethylamine in hot methanol gave O,O′-bonded [Pt{OC( NO)C₆H₄OH}(PPh₃)₂], but [PtCl₂(cod)](cod = cycloocta-1,5-diene) gave N,O-bonded [Pt{OC₆H₄C(O)NOH}(cod)]. Ligand substitution gives other N,O bonded complexes, including [Pt{OC₆H₄C(O)NOH}(PPh₃)₂]. Reaction of K₂PtCl₄ with 2 equiv. of EPh₃(E = As or Sb), salicylhydroxamic acid and excess trimethylamine gives products whose structures depend on E; AsPh₃ gives [Pt{OC( NO)C₆H₄OH}(AsPh₃)₂], while SbPh₃ gives [Pt{OC₆H₄C(O)NOH}(SbPh₃)₂].

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  • A low-toxicity method for the separation of lanosterol and dihydrolanosterol from commercial mixtures

    Kavtaradze, Levan K.; Manley-Harris, Merilyn; Nicholson, Brian K. (2004-09-01)

    Journal article
    University of Waikato

    We describe an inexpensive, low-toxicity and high-yielding method for the production of pure lanosterol and dihydrolanosterol from the commercially available mixture. Optimum conditions are presented for the one-pot production of the intermediate 24,25 vicinal diol of lanosterol acetate (via either epoxidation or hydroxyhalogenation) which is readily separated from the unreacted dihydrolanosterol acetate. The lanosterol diol can then be converted to pure (>97%) lanosterol. Hypophosphorous acid was used for both the conversion of the epoxide to the diol, and as a catalyst for the hydroxyhalogenation by N-halosuccinimides of the olefinic bond.

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  • Synthesis, characterisation, supramolecular aggregation and biological activity of phosphine gold(I) complexes with monoanionic thiourea ligands

    Henderson, William; Nicholson, Brian K.; Tiekink, Edward R. T. (2006-01-01)

    Journal article
    University of Waikato

    A series of phosphine gold(I) complexes containing monoanionic thiourea ligands has been synthesised by reaction of the appropriate precursor chloro complex, Ph₃PAuCl, Cy₃PAuCl, dppf(AuCl)₂ [dppf = Fe(η⁵-C₅H₄PPh₂)₂] or dppe(AuCl)₂ (dppe = Ph₂PCH₂CH₂PPh₂) with the thiourea and Me₃N base in methanol solution. The complexes have been fully characterised by elemental analysis, NMR spectrometry, electrospray mass spectrometry, and in several cases, by single-crystal X-ray diffraction studies. The crystallographic studies show that the ligands coordinate as a thiolate in each case with systematic variations in geometric parameters being readily ascribed to the influence of the N-bound substituents. In four of the structures, discernable supramolecular aggregation patterns are evident, leading to loosely associated dimers or chain motifs, the latter mediated by either Au S, N–H N or C–H O interactions. Cytotoxicity data, against the P388 leukemia cell line, and anti-microbial data are also reported.

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  • Dinuclear platinum(II) complexes containing ferrocenylalkyl–thiolate and –selenolate ligands

    Devoy, Sarah M.; Henderson, William; Nicholson, Brian K. (2013)

    Journal article
    University of Waikato

    Alkylation reactions of [Pt₂(μ-S)₂(PPh₃)₄] with haloalkylferrocenes FcCH₂Cl, Fc(CH₂)₆Br and Fc(CH₂)₁₁Br [Fc = (η⁵-C₅H₅)Fe(η⁵-C₅H₄)] gave the cationic μ-thiolate complexes [Pt₂(μ-S){μ-S(CH₂)nFc}(PPh₃)₄]⁺ (n = 1, 6, 11), isolated as PF₆⁻ and/or BPh₄⁻ salts, and characterised by ESI mass spectrometry, NMR spectroscopy, microelemental analysis, and by an X-ray structure determination on [Pt₂(μ-S){μ-SCH₂Fc}(PPh₃)₄]PF₆. The complex contains the typical folded {Pt₂(μ-S)₂} core with an axial ferrocenylmethylthiolate ligand. The corresponding selenolate complex [Pt₂ (μ-Se){μ-SeCH₂Fc}(PPh₃)₄]⁺ was similarly obtained by alkylation of [Pt₂(μ-Se)₂ (PPh₃)₄] with FcCH₂Cl, and isolated as PF₆⁻ and BPh₄⁻ salts. The attempted liberation of FcCH₂SH from [Pt₂(μ-S){μ-SCH₂Fc}(PPh₃)₄]+ using Na₂S was not successful.

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  • Dimeric rhodium(III), iridium(III) and ruthenium(II) thiosalicylate complexes

    Henderson, William; Nicholson, Brian K.; Oliver, Allen G.; Rickard, Clifton E.F. (2001-04-01)

    Journal article
    University of Waikato

    Reactions of the chloride-bridged dimers [LMCl(μ-Cl)]₂ (M=Rh, Ir; L=Cp*=η⁵-C₅Me₅; M=Ru, L=η⁶-p-cymene) with two mole equivalents of thiosalicylic acid (HSC₆H₄CO₂H, H₂tsal) and excess base gives the dimeric rhodium(III), iridium(III) and ruthenium(II) thiosalicylate complexes [LM(tsal)]₂. Reaction of the complex [Cp*RhCl₂(PPh₂)] with one equivalent of H₂tsal and triethylamine in dichloromethane gives a mixture of the dimer [Cp*Rh(tsal)]₂ and the phosphine complex [Cp*Rh(tsal)(PPh₃)]; upon recrystallisation, pure dimer is obtained. A single-crystal X-ray diffraction study on the rhodium and ruthenium dimers reveals the expected thiolate-bridged M₂(μ-S)₂ unit. Electrospray mass spectrometry (ESMS) is a useful technique in studying the chemistry of the thiosalicylate complexes, all complexes giving strong [M+H]⁺ ions. With added thiosalicylic acid, cations of the type [(LM)₂(Htsal)₃]⁺ were detected in the mass spectra.

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  • Thiourea monoanion and dianion complexes of rhodium(III) and ruthenium(II)

    Henderson, William; Nicholson, Brian K.; Dinger, Maarten B.; Bennett, Rachel L. (2002-10-01)

    Journal article
    University of Waikato

    The versatility of deprotonated thioureas as ligands is shown by the synthesis and characterisation of a range of rhodium(III) complexes of substituted thioureas, with support from a ruthenium(II) analogue in one case. Reaction of the complexes [LMCl(μ-Cl)]2 [M=Rh, L=η5-C5Me5 (Cp*); M=Ru, L=η6-p-cymene] with Na[MeNHC(S)NCN] and excess trimethylamine base gives the dinuclear complexes [LM{SC(=NCN)NMe}]2 containing chelate-bridging thiourea dianion ligands. The Ru complex was characterised by an X-ray diffraction study. The mononuclear complexes [Cp*Rh{SC(=NCN)NMe}(PPh3)] and [Cp*Rh{SC(=NPh)NPh}(PPh3)], containing chelating thiourea dianion ligands, were prepared by analogous reactions in the presence of triphenylphosphine. Reaction of [Cp*Rh{SC(=NCN)NMe}(PPh3)] with HCl, or [Cp*RhCl(μ-Cl)]2 with 2 equiv. of PPh3 and Na[MeNHC(S)NCN] (with no added base) gave the complex [Cp*RhCl{SC(=NCN)NHMe}(PPh3)], containing a (monodentate) S-bonded thiourea monoanion ligand, which was characterised by an X-ray diffraction study. The AsPh3 and SbPh3 analogues of this complex were also prepared and characterised. Reaction of [Cp*RhCl(μ-Cl)]2 with 2 equiv. of PPh3 or SbPh3 and PhNHC(S)NHPh or various trisubstituted thioureas PhNHC(S)NR1R2, triethylamine and NaBPh4 gave a range of cationic complexes [Cp*Rh{SC(=NR1R2)NPh}(EPh3)]+ (E=P, Sb), as their tetraphenylborate salts, in which the thiourea is bonded as a monoanion through the S and the NPh group. The corresponding reaction utilising 1,6-bis(diphenylphosphino)hexane (dpph) gave the dinuclear complex [Cp*Rh{SC(=N(CH2CH2)2O)NPh}]2(μ-η2-dpph) (BPh4)2.

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  • Synthesis and crystal structure of the first complex containing a chelating selenourea dianion ligand

    Nicholson, Brian K.; Henderson, William; Dinger, Maarten B. (2003-11-01)

    Journal article
    University of Waikato

    Reaction of N,N′-diphenylselenourea, PhNHC(Se)NHPh, with cis-[PtCl2(PPh3)2] and triethylamine in hot methanol gives the first example of a selenourea dianion complex, [Pt{SeC(=NPh)NPh}(PPh3)2] isolated as a yellow solid in high yield. The structure of the complex was determined by X-ray crystallography and found to be similar to the related thiourea dianion complex [Pt{SC(=NPh)NPh}(PPh3)2], with a Pt---Se---C---N four-membered ring. The antitumour activity (P388 murine leukaemia cells) of the selenourea dianion complex was determined, together with a small selection of related platinum(II)-thiourea dianion complexes (prepared by an analogous method) for comparison. The complex [Pt{SC(=NMe)NMe}(PPh3)2] showed high activity [IC50 1.0 μM], with the other complexes showing moderate to low activity.

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