Browsing by Author "Hilts, Robert"

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    An unusual example of allyl-to-alkynyl migration in a phenylacetylide-bridged heterobinuclear complex of rhodium and iridium
    (1999) George, Darren S. A.; Hilts, Robert; McDonald, Robert; Cowie, Martin
    The reactivity of the alkynyl-bridged complex [RhIr(CO)2(μ2-η1:η2-C2Ph)(dppm)2][X] (X = BF4 (1a), SO3CF3 (1b); dppm = Ph2PCH2PPh2) with electrophiles has been demonstrated. Protic acids HX (X = BF4, SO3CF3) first yield the oxidative-addition products [RhIr(X)(CO)2(μ-H)(μ-C2Ph)(dppm)2][X], which under carbon monoxide result in displacement of the weakly coordinating BF4- or SO3CF3- anions and subsequent conversion to the vinylidene-bridged [RhIr(CO)4(μ-CC(H)Ph)(dppm)2][X]2. Reaction of 1 with allyl halides yields the allyl vinylidene-bridged compounds [RhIr(Y)(CO)(μ-CC(Ph)CH2CHCH2)(μ-CO)(dppm)2][X] (Y = Br (5), Cl (6)), by coupling of the alkynyl and allyl groups at the β-position of the alkynyl moiety. NMR studies at low temperatures show coordination of allyl halide at Ir at −80 °C, followed by allyl halide loss and subsequent oxidative addition at −50 °C. The oxidative-addition intermediates, [RhIr(η1-CH2CHCH2)(CO)2(μ-Y)(μ-C2Ph)(dppm)2][X] (Y = Br (9), Cl (10)), rearrange to the allylvinylidene products (5 and 6) at ambient temperature. Although halide removal from compounds 5 and 6, using AgBF4, does not result in destabilization of the allylvinylidene fragment, resulting instead in replacement of halide by fluoborate ion, the reaction of 1 with allyl halide in the presence of a silver salt does not lead to coupling of the allyl and alkynyl moieties, but gives [RhIr(η3-C3H5)(CO)(μ-C2Ph)(μ-CO)(dppm)2][X]2 (13). Addition of halide ion to this η3-allyl complex at ambient temperature again leads to formation of 5 or 6. On the basis of these results a mechanism is proposed for the allyl/alkynyl coupling reaction.
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    Carboxylic acid abundances in the Tagish Lake meteorite: lithological differences and implications for formic acid abundances in carbonaceous chondrites
    (2009) Hilts, Robert; Herd, Christopher D. K.; Morgan, Don; Edwards, LeAnne; Huang, Yongsong
    The most abundant soluble organic compounds in carbonaceous chondrites are typically carboxylic acids (Pizzarello et al 2001). Strait-chain monocarboxylic acids up to C-12 have been the focus of considerable attention owing to the exciting possibility that they may have been incorporated into the molecular architecture of prebiotic protomembranes on the ancient Earth (e.g., Silva et al 2004.) The most abundant monocarboxylic acid in interstellar space is formic acid (e.g. Remigen et al. 2003; Snyder 2008). It is generally accepted that the organic material in carbonaceous chondrites such as the Tagish Lake meteorite, which includes carboxylic acids, is derived from interstellar or nebular sources (Cronin et al 1988 and Cronin et al 1993). It is somewhat surprising, therefore, that up until now only what have been described as small or moderate formic acid concentrations have been found in aqueous extracts of carbonaceous chondrites (Huang et al 2005, Naraoka et al 1999, Yuen et al 1973, Shimoyama et al 1986, Yuen et al 1984 and Krishnamurthy et al 1992). Previous reports have ascribed the unexpectedly low formic acid abundances to either compound loss during extraction and subsequent work up, or to depletion caused by evaporation and/or aqueous leaching of the compound from the meteorite upon its exposure to the Earth's hydrosphere (Huang et al 2005 and Naraoka et al 1999). Here we present our analysis of the water-soluble monocarboxylic acids in two different lithologies within the Tagish Lake meteorite using the SPME-GCMS procedures recently developed by Huang et al 2005 to compare the two lithologies in this respect. Our results conclusively show that formic acid is, by a wide margin, the most abundant monocarboxylic acid in both of the Tagish Lake lithologies investigated thus far. This is in stark contrast to all previous studies of other meteorites in which it was concluded that the formic acid concentration was the lowest or one of the lowest of those monocarboxylic acids present in the extract (Huang et al 2005, Naraoka et al 1999, Yuen et al 1973, Shimoyama et al 1986, Yuen et al 1984 and Krishnamurthy et al 1992). Moreover, our serendipitous discovery that formic acid has a very low response factor when run on either GCMS(quadrupole) or GC-FID (Allen et al 1987) instruments suggests that previous studies on carbonaceous chondrites may have dramatically underestimated the quantities of formic acid present. Also, a close inspection of the relative abundances for the straight-chain monocarboxylic acids in each Tagish Lake lithology has led us to conclude that the overall oxidation levels for the water soluble organics from the two lithologies are different. Lastly, we have found that the monocarboxylic acids within the Tagish Lake meteorite are enriched in deuterium compared to terrestrial organics, with delta D values ranging from + 247 to + 581%o. These results confirm that the acids originate from interstellar space and that terrestrial contamination has been largely avoided.
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    Carboxylic acid abundances in the Tagish Lake meteorite: lithological differences and implications for formic acid abundances in carbonaceous chondrites
    (2009) Hilts, Robert; Herd, Christopher D. K.; Morgan, Don; Edwards, LeAnne; Huang, Yongsong
    Analysis of two different Tagish Lake rocks found: 1) a very low GCMS response for formic acid, 2) formic acid concns above 100 ppm and 3) that formic acid to higher homologue ratios indicate the average level of oxidation for the soluble organics.
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    Cold curation of pristine astromaterials: insights from the Tagish Lake meteorite
    (2016) Herd, Christopher D. K.; Hilts, Robert; Skelhorne, Aaron W.; Simkus, Danielle N.
    The curation and handling of volatile-bearing astromaterials is of prime importance in current and future plans for sample return missions to targets containing organic compounds, ices, or other volatile components. We report on the specific curation constraints required for the preservation of the Tagish Lake meteorite, a C2 ungrouped chondrite that contains significant concentrations of organic matter, including compounds of prebiotic interest or volatile in character, and which was recovered from a frozen lake surface a few days after its fall. Here we review the circumstances of the meteorite’s handling, its complement of intrinsic and contaminant organic compounds, and an unusual reaction between some of the specimens and the Al foil in which they were enclosed. From our results we derive the requirements for curation of the meteorite, and describe a specialized facility that enables its curation and handling. The Subzero Facility for Curation of Astromaterials consists of a purified Ar glove box enclosed within a freezer chamber, and enables investigations relevant to curation of samples at or below -10 °C. We provide several recommendations based on insights obtained from the commissioning and initial use of the facility that are relevant to collection of freshly fallen meteorites, curation of volatile-bearing meteorites and other astromaterials, and planning and implementation of curation plans for future sample return missions to volatile-bearing targets.
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    Complexes of multifunctional phosphorus ligands. Rhenium(V) complexes of the multidentate phenoxyphosphine ligands bis(o-trimethylsilyloxyphenyl)phenylphosphine and tris(o-trimethylsilyloxyphenyl)phosphine. Stepwise elimination of Me3SiX (X = Cl, OEt) from the metal-ligand system
    (1998) Cavell, Ronald G.; Hilts, Robert; Luo, Hongyan; McDonald, Robert
    The silylated aryloxo ligands bis(o-silyloxyphenyl)phenylphosphine (abbreviated PhP{OT}2) and tris(o-trimethylsilyloxyphenyl)phosphine (abbreviated P{OT}3, where T = Me3Si) were prepared. Complexation reactions with OReCl2(OEt)(PPh3)2 and OReCl3(PPh3)2 proceed by displacement of one PPh3 and the subsequent stepwise replacement of the OEt and/or Cl substituents. The new complex Re(O)Cl2[κ2-(P,O)-(PhP{O}{OT})](PPh3), formed by elimination of Me3SiOEt, exists in diastereomeric cis and trans forms. Elimination of a second equivalent of Me3SiCl gives Re(O)Cl[κ3-(P,O,O)-(PhP{O}2)](PPh3). Similarly P{OT}3 converts Re(O)Cl2(OEt)(PPh3)2 to ReOCl2[κ2-(P,O)-(P{O}{OT}2)](PPh3) (5) (structurally characterized as 5·0.875CH2Cl2): crystal data; triclinic P1̄, a = 14.302(4) Å, b = 18.734(2) Å, c = 17.639(4) Å, α = 80.950(12)°, β = 80.12(2)°, γ = 81.76(2)°, Z = 4. Final R1 and wR2 values are 0.0852 and 0.1525, respectively on Fo2 > 2σ(Fo2) data (or 0.1948 and 0.2019 on all data). The phenoxy phosphine ligand in 5 is bound via P and one O to Re. The P atoms are mutually cis to each other and to the terminal oxygen on Re. Two ortho-trimethylsiloxy substituted phenyl rings dangle from the coordinated phosphorus atom. Complex 5 can be converted to Re(O)Cl[κ3-(P,O,O)-(P{O}2{OT})](PPh3) (6) by treatment with PPN+ Cl- and 6 was also obtained by direct reaction of Re(O)Cl3(PPh3)2 with P{OT}3 at higher temperatures. The complex 6 has been structurally characterized: crystal data triclinic, P1̄, a = 10.1509(6) Å, b = 12.1123(8) Å, c = 16.2142(14) Å, α = 97.851(7)°, β = 94.852(7)°, γ = 96.889(6)°, Z = 2. Final R1 and wR2 values were 0.0303 and 0.0721 on Fo2 > 2σ(Fo2) data (or 0.0348 and 0.0742 on all data). The phenoxyphosphine ligand in 6 is bound facially to Re through P and two of the phenoxy oxygens. The Ph3P group and terminal oxygen atoms are cis to the oxygen atoms of the phenoxy ligands and the Cl lies trans to P. One trimethylsiloxyphenol group dangles. Careful hydrolysis of 6 gave Re(O)Cl[κ3-(P,O,O)-(P{O}2{OH})](PPh3) which was also formed during complexation reactions in moist solvent. Solution 31P{1H} NMR demonstrated cis- or trans-(P,P) geometry for the complexes, which was confirmed in the two aforementioned cases by structure determinations.
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    Compound-specific carbon isotope compositions of aldehydes and ketones in the Tagish Lake meteorite
    (2016) Simkus, Danielle N.; Aponte, José C.; Hilts, Robert; Elsila, Jamie E.; Herd, Christopher D. K.
    Investigating the aldehyde and ketone content of astromaterials provides insight into the abiotic formation of prebiotic compounds on asteroid parent bodies, as aldehydes and ketones are the chemical precursors to α-amino acids in Strecker synthesis reactions. Elucidating amino acid synthesis reactions is important for understanding the origin of prebiotic compounds on Earth and the potential for life beyond our planet. Aldehydes and ketones have been previously detected via gas chromatography mass spectrometry (GC-MS) in a few carbonaceous chondrite meteorites, including Murchison, Bells and Ivuna. However, carbon isotope compositions of aldehydes and ketones in meteorites have not yet been measured. As such, their relationship to amino acids and other compound classes in meteorites have not been fully investigated. Here, we present the first report of compound specific carbon isotope measurements of aldehydes and ketones in meteorite samples.
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    Compound‐specific carbon isotope compositions of aldehydes and ketones in the Murchison meteorite
    (2019) Simkus, Danielle N.; Aponte, José C.; Hilts, Robert; Elsila, Jamie E.; Herd, Christopher D. K.
    Compound‐specific carbon isotope analysis (δ13C) of meteoritic organic compounds can be used to elucidate the abiotic chemical reactions involved in their synthesis. The soluble organic content of the Murchison carbonaceous chondrite has been extensively investigated over the years, with a focus on the origins of amino acids and the potential role of Strecker‐cyanohydrin synthesis in the early solar system. Previous δ13C investigations have targeted α‐amino acid and α‐hydroxy acid Strecker products and reactant HCN; however, δ13C values for meteoritic aldehydes and ketones (Strecker precursors) have not yet been reported. As such, the distribution of aldehydes and ketones in the cosmos and their role in prebiotic reactions have not been fully investigated. Here, we have applied an optimized O‐(2,3,4,5,6‐pentafluorobenzyl)hydroxylamine (PFBHA) derivatization procedure to the extraction, identification, and δ13C analysis of carbonyl compounds in the Murchison meteorite. A suite of aldehydes and ketones, dominated by acetaldehyde, propionaldehyde, and acetone, were detected in the sample. δ13C values, ranging from −10.0‰ to +66.4‰, were more 13C‐depleted than would be expected for aldehydes and ketones derived from the interstellar medium, based on interstellar 12C/13C ratios. These relatively 13C‐depleted values suggest that chemical processes taking place in asteroid parent bodies (e.g., oxidation of the IOM) may provide a secondary source of aldehydes and ketones in the solar system. Comparisons between δ13C compositions of meteoritic aldehydes and ketones and other organic compound classes were used to evaluate potential structural relationships and associated reactions, including Strecker synthesis and alteration‐driven chemical pathways.
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    Coordination chemistry of [CH2(PPh2) (P(Y)R2)] and [CH(PPh2)(P(Y)R2)]−, Y = S or Se, R = Ph or tBu: rhodium, iridium and ruthenium complexes; 13C 31P, and 77 Se NMR studies; and the crystal and molecular structures of [Ir(cod)CH2(PPh2)(P(S)tBu2)-P,S]BF4 · CHCl3, [Rh(cod)CH2(PPh2)(P(S)tBu2)-P,SClO4 · CH2Cl2 [Rh(cod)CH(PPh2) (P(S)Ph2)-P,S] and [RuCl2(p-cymene)CH2(PPh2)(P(S) Ph2) -P] · CH2Cl2
    (1992) Browning, Jane; Bushnell, Gordon W.; Dixon, Keith R.; Hilts, Robert
    Reactions of the chloro-bridged complexes, [M2Cl2(cod)2], M  Ir or Rh, COD  cyclooctadiene, with CH2(PPh2)(P(Y)R2), Y  S or Se, R  Ph or tBu, provide a synthetic route to the cations, [M(cod)(CH2(PPh2)(P(Y)R2)-P,S]+, which are isolated as fluoroborate or perchlorate salts. Treatment of these products with sodium hydride results in facile deprotonation to the neutral complexes, [M(cod)CH(PPh2)(P(Y)Ph2)-P,S)], and when Y  S, the neutral complexes are also accessible via reactions of [M2Cl2(cod)2] with Li[CH(PPh2)(P(S)R2)]. Reactions of the cations, [M(cod)CH2(PPh2)(P(S)tBu2)-P,S)]+ with other ligands, Lg  (CO)2, (CNtBu)2, or bis(diphenylphosphino)methane (dppm), result in displacement of cod to form [M(Lg)(CH2(PPh2)(P(S)tBu2)-P,S]+. Ruthenium complexes of CH2(PPh2)(P(S)Ph2) are accessiblevia similar bridge cleavage reactions using [Ru2Cl4L2], L  benzene or p-cymene. These complexes are characterized by complete 13C, 31P, and 77Se nuclear magnetic resonance (NMR) studies and by four crystal structure determinations. The complexes [Ir(cod)(CH2(PPh2)(P(S)tBu2)-P,S]BF4·CHCl3 (1), [Rh(cod)(CH2(PPh2)(P(S)tBu2)-P,S]ClO4·CH2Cl2 (2), [Rh(cod)(CH(PPh2)(P(S)Ph2-P,S] (3) and [RuCl2(p-cymene)(CH2(PPh2)(P(S)Ph2)-P]· CH2Cl2 (4) crystallize in the P (No. 2) space group (Z  2) with respective unit cells: a = 12.307(7) Å, b = 14.743(8) Å, c = 10.877(6) Å, α =74.42(5)°, β = 107.65(6)°, γ = 105.47(5)°; a = 12.163(1) Å, b = 14.56(1) Å, c = 10.560(1) Å, α = 77.69(1)°, β = 74.54(1)°, γ = 77.01(1)°; a = 10.650(4) Å, b = 13.327(4) Å, c = 10.419(3) Å, α = 90.60(3)°, β = 102.64(3)°, γ = 83.15(3)°; a = 11.217(2) Å, b 17.124(3) Å, c = 10.412(2) Å, α = 90.58(1)°, β = 112.29(2)°, γ = 97.53(2)°. Complexes 1–3 all contain bidentate P,S-bonded ligands occupying two coordination positions of an approximately square planar metal centre. In each case, the coordination is completed by two double bonds of a cod ligand. In contrast, complex 4 contains a monodentate P-bonded ligand.
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    Coordination chemistry of [CH{P(S)Ph2}2]−: x-ray diffraction studies of S,S-chelate complexes of iridium and rhodium
    (1992) Browning, Jane; Bushnell, Gordon W.; Dixon, Keith R.; Hilts, Robert
    Reactions of the chloro-bridged complexes, [M2Cl2(cod)2], M  Ir or Rh, with CHR(P(S)Ph2)2, R  H or Me, provide a synthetic route to the cations, [M(cod){CHR(P(S)Ph2)2-S,S}]+, which are isolated as fluoroborate or perchlorate salts. Treatment of these products with sodium hydride results in facile deprotonation to the neutral complexes, [M(cod){CR(P(S)Ph2)2-S,S}], and when R  H, the neutral complexes are also accessible via reactions of [M2Cl2(cod)2] with Li[CH{P(S)Ph2)2]. The complexes, [Ir(cod){CH(P(S)Ph2)2-S,S}], and [Rh(cod){CH(P(S)Ph2)2-S,S}], crystallize in the P1 (No. 2) space group (Z = 2) with respective unit cells: a = 11.570(4), b = 15.122(2), c = 9.919(3) Å, α = 79.86(4), β = 64.87(3), γ = 97.94(4)°; and α = 11.571(16), b = 15.078(2), c = 9.869(2) Å, α = 100.16(1), β = 64.97(1), γ = 82.10(1)°. Both structures consist of puckered 6-membered rings formed by coordination of the disulfide ligands via two sulfur atoms to the metal center. The rings lie in distorted boat conformations with the prows occupied by one sulfur and one phosphorus and the metal atoms in one side.
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    Coordination chemistry of unsaturated cyclic and acyclic PNS and PNSe ligands
    (1994) Chivers, Tristram; Hilts, Robert
    This review is primarily concerned with the synthesis, structure and fluxional behaviour of cyclic and acyclic chalcogen-nitrogen systems containing phosphorus (V) or phosphorus (III). The cyclic Ph4P2N4S2R− and Ph4P2N4S2−2 anions (and their selenium analogues) are versatile ligands for both early and late transition metals. Mono-, di-, tri- and tetradentate bonding modes have been established for the eight-membered P2N4S2 ring in these inorganic heterocycles. Ligation occurs through sulphur (or selenium) and/or nitrogen, while the coordinatively saturated phosphorus (V) centres serve as an informative probe of fluxional processes. By contrast, coordination occurs exclusively through phosphorus in both the cyclic and acyclic phosphorus (III) systems.
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    Creation of a cryogenic, inert atmosphere sample curation facility: establishing baselines for sample return missions
    (2012) Herd, Christopher D. K.; Hilts, Robert; Skelhorne, Aaron W.
    A new facility for handling and curiation of meteorites within a sub-zero environment under an Ar atmosphere has been established. Baseline contaminants within the glovebox containing the astromaterials will be described.
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    Creation of a cryogenic, inert atmosphere sample curation facility: update
    (2013) Hilts, Robert; Skelhorne, Aaron W.; Herd, Christopher D. K.
    Introduction: As reported previously [1] we have established a cryogenic facility for curation and handling of planetary materials at the University of Alberta. Established in order to enable curation and handling of the organic-rich Tagish Lake meteorite [e.g., 2], the facility consists of a state-of-the art Ar gas glove box, housed within a -20 °C controlled environment chamber. The Ar gas is purified with an MB 20 G gas purifier (MBraun, Inc.) and continually recirculated. A Class 1000 clean room serves as a room temperature anteroom and source of clean air for the -20 °C chamber. Results of ongoing studies of baseline contaminants and operating parameters are reported here. Effect of temperature on volatile organics: The glove box atmosphere was previously sampled using a solid phase microextraction fibre (SPME), exposed for 28 days at room temperature (Sept. 29 to Oct. 27, 2011). GC-MS analysis of the SPME fibre revealed common organic chemicals such as styrene and aniline [1]. To test our hypothesis that low temperatures should lead to lower levels of organic vapours in the glove box atmosphere, an SPME fibre was stored in the glove box at the standard operating temperature of -20 °C for a period of 54 days (Sept. 26 to Nov. 19, 2012). GC-MS analysis on the fibre revealed that styrene and aniline were absent in the low temperature sample. Apparently, the combination of a lower temperature and decreasing rate of outgassing from glove box components over time combined with repeated flushing of the box with Ar gas effectively eliminated the vast majority of the vapor phase organic contaminants from the box. The evolution of the composition of the atmosphere over the next 10-12 months will be monitored by periodic sampling with SPME fibres. Glove composition: The original HypalonTM gloves provided with the glove box were found to be too stiff for at the nominal -20 °C operating temperature. They were subsequently replaced with gloves made from polyurethane, which retains serviceable elasticity down to -20 °C. In order to determine the nonvolatile organic residue on the surface of the new polyurethane gloves, the drippings from the passage of approximately 1 mL of ultrapure dichloromethane over a 2 cm x 2 cm piece of polyurethane glove material was analyzed by GC-MS. Not surprisingly, the GC trace of the glove dichloromethane rinse was found to contain the two monomeric species, viz. methylene diphenyl diisocyanate and 2,2'-(1,4-butanediyl)bis-oxirane, from which the polyurethane polymer material that forms the basis of the gloves was derived. Clearly, a dichloromethane rinse of the gloves prior to their installation is essential to stop the transfer of these nonvolatile organics to the interior of the glove box and ultimately the surfaces of any planetary materials being processed therein. References: [1] Hilts R.W. et al. 2012. Meteoritics & Planetary Science 47:A186. [2] Herd C.D.K. et al. 2011. Science 332:1304-1307.
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    Development of a GC-MS-SPME method for the determination of amines in meteorites
    (2016) Hilts, Robert; Skelhorne, Aaron W.; Simkus, Danielle N.; Herd, Christopher D. K.
    A GC-MS-SPME analytical method for the direct determination of amines in aqueous solution has been developed. The key step in the procedure is the conversion of the amines into their non-volatile ammonium salts by protonation with HCl.
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    Development of a new SPME-GCMS method for the determination of amines in meteorites
    (2016) Hilts, Robert; Skelhorne, Aaron W.; Herd, Christopher D. K.; Simkus, Danielle N.
    Introduction: Amines are polar, water-soluble organics found in all meteorites that contain amino acids. It has been proposed that meteoritic amines are produced by the thermal decarboxylation of amino acids[1]. The analysis of amines using GC-MS techniques has proven to be problematical owing to the high water solubility and high volatility of these compounds. In addition, the strong interactions of polar amine molecules with the stationary phase of a typical polysiloxane column lead to extensive tailing, poor resolution of peaks and low detector response [2]. To circumvent these disadvantages the highly polar amines have been converted to less polar derivatives that are more amenable to GC analysis by substitution of amine N-H hydrogens with weakly polar moieties such as acyl, silyl, dinitrophenyl and methyl groups [2]. The derivatives of amines generally have much weaker interactions with stationary phases and thus are more volatile in terms of their chromatographic behavior, which leads to better separation on the column. In the last decade base-deactivated columns that give good separations of underivatized aliphatic and aromatic amines have been successfully developed [3]. Consequently, volatile amines in aqueous media can now be routinely and reproducibly analyzed by the combination of SPME(solid- phase microextraction) techniques with base-deactivated GC columns that have been specifically engineered to directly separate amines(see for example [4]). The great advantage of this analytical method is that it sidesteps derivatization,which invariably entails the loss of amines, especially those that are more volatile, through side reactions and incomplete transfer during isolation and workup. Results and Discussion: An aqueous test solution containing an in-house collection of amines standards, viz. N-ethylaniline (100 ppm), dipropylamine (100 ppm), methylamine (100 ppm) and piperidine (100 ppm) was prepared in 80 mL of Millipore water. The majority of this solution (70 mL) was set aside for SPME-GC(CP Volamine)MS analysis while the remaining 10 mL was adjusted to ca. pH = 2 using concentrated HCl to convert all of the amines into their corresponding, non-volatile ammonium salts. The water from this acidified mixture was removed on a rotary evaporator , affording a colourless residue. The solid was dissolved in ca. 3 mL of Millipore water and the pH was brought up to 8 by adding ca. 1 mL of 8 M NaOH(aq). The SPME –GC(CP-Volamine) trace of the reconstituted amine mixture was found to contain the same four amine standards as were seen in solution prior to the protonation step. Thus, this result proves that our amine to ammonium to amine methodologycan be used for the direct determination of volatile alkyl amines and aromatic amines. Application of our new SPME-GC(CP-Volamine)MS method to an aqueous extract of a 2-gram sample of the Tagish Lake stone10a afforded a GC trace that contained three different polar aromatic compounds, namely acetophenone , 4-phenylpyridine and 2-phenyl-1,2-propane diol. In the absence of any isotope ratio data, we cannot conclude whether these three aromatic species are indigenous or terrestrial contaminants. It should be pointed out, however, that acetophenone, has been liberated from the Tagish Lake meteorite by the application of heat [5], and thus it does not seem unreasonable to conclude that the acetophenone seen in the trace for 10a likely has an extraterrestrial origin. References: [1] M.A. Sephton, Astronomy and Geophysics, Vol. 45(2), p. 2.8-2.14 (2004). [2] H. Kataoka, Journal of Chromatography A, 733 (1996) 19-34. [3] "An Advanced Base Deactivated Capillary Column for analysis of Volatile amines, Ammonia and Alcohols.", Jaap de Zeeuw, Ron Stricek and Gary Stidsen, Restek Corp. Bellefonte, USA. [4] L. Muller, E. Fattore and E. Benfenati, Journal of Chromatography A, 791 (1997), 221-230. [5] H. Yabuta, G.D. Cody and C.M.O.D. Alexander (2007). Abstract # 2304, 38th Lunar and Planetary Science Conference.
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    Dialkyl and trialkyl heterobinuclear complexes of rhodium and iridium: models for adjacent-metal involvement in bimetallic catalysts
    (2005) Hilts, Robert; Oke, Okemona; Ferguson, Michael J.; McDonald, Robert; Cowie, Martin
    The heterobinuclear dialkyl complexes [RhIr(R)2(μ-CO)(dppm)2] (dppm = μ-Ph2PCH2PPh2; R = CH3 (2), CH2Ph (3)) have been prepared. Both A-frame-like compounds have one alkyl group terminally bound to each metal and a bridging carbonyl ligand. Some subsequent reactivity studies of 2 are reported. Reaction of 2 with CO yields [RhIr(CO)3(dppm)2] and acetone. If this reaction is monitored at low temperature by NMR spectroscopy, the dicarbonyl species [RhIr(CH3)2(CO)2(dppm)2] (4) is first observed, followed by [RhIr(CH3)2(CO)3(dppm)2] (5). In both products, both methyl groups are bound to Ir. Warming to ambient temperature under CO yields acetone and [RhIr(CO)3(dppm)2]. Crossover experiments suggest that acetone arises primarily from an intramolecular process. We propose that migratory insertion of a CO and a methyl group occurs on Ir; presumably reductive elimination also occurs from this metal. Compound 2 reacts with H2 at −78 °C to yield [RhIrH(CH3)2(μ-H)(μ-CO)(dppm)2] (6), in which one methyl group is bound to Rh while the other, together with a hydride ligand, is terminally bound to Ir. This latter species reacts with CO at 0 °C to yield [RhIrH(C(O)CH3)(CH3)(μ-H)(μ-CO)(dppm)2] (7), in which migratory insertion involving CO and the Rh-bound methyl group has yielded a Rh-bound acetyl group. At ambient temperature, under an atmosphere of CO, [RhIr(CO)3(dppm)2] is formed, together with acetaldehyde and methane. Crossover experiments support a predominantly intramolecular process for acetaldehyde formation but are equivocal on the formation of methane. Compound 2 oxidatively adds CH3I or n-C4H9I, yielding [RhIr(CH3)2(R)(μ-I)(μ-CO)(dppm)2] (R = CH3, n-C4H9), in which the added alkyl group in each case is bound to Ir. The n-butyl product reacts with CO to yield [RhIr(n-C4H9)(CH3)2(μ-CO)2(dppm)2][I], in which the n-butyl group has migrated to Rh. A similar product, [RhIr(CH3)3(μ-CO)2(dppm)2][CF3SO3], is obtained in the reaction of 2 with methyl triflate in the presence of CO.
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    Diphosphine-bridged, heterobimetallic complexes containing iridium and osmium. Reversible orthometalation of a bridging bis(diphenylphosphino)methane group at the iridium center promoted by the adjacent osmium center
    (1991) Hilts, Robert; Franchuk, Roberta; Cowie, Martin
    The compound (PPN)[HOs(CO)4] reacts readily with [IrCl(i)1 2-dppm)2] (PPN+ = (Ph3P)2N+, dppm = Ph2PCH2PPh2) at ambient temperature, yielding the heterobinuclear complex [IrOs(H)2(CO)3(#t2-’?3-(oCeH^PhPCI^PPh^(dppm)] (1), in which one phenyl group is ortho-metalated at the Ir center. Treatment of 1 with the electrophile sources HBF4-Et¡>0 or [AuPPh3]BF4 reverses the ortho metalation to give the hydrido-bridged species, [IrOs(CO)3Gt-H)(M-X)(dppm)2][BF4] (X = H (2), AuPPh3 (3)). Deprotonation of 2 with use of NaH regenerates compound 1. The AuPPh3 group in 3 is readily replaced by an iodo group in the reaction with I2 to give [IrOs(CO)3^-H)(/¿-I)(dppm)2] [BF4] (4). Under a CO atmosphere, compound 2 yields [IrOs(CO)6(dppm)2] [BF4] (5), and reaction of 5 with Me3N0-2H20 results in loss of one carbonyl group from the Ir center to yield [IrOs(CO)4(dppm)2] [BF4] (6). The structure of 5 has been determined by X-ray techniques. This compound crystallizes, together with 1.5 equiv of CH2C12, in the monoclinic space group P2,/c, with cell parameters o = 12.063 (2) Á, b = 22.725 (3) Á, c = 22.050 (3) Á, ß = 101.66 (1)°, V = 5920 A3, and Z = 4. The structure has refined to R = 0.043 and f?w = 0.063 on the basis of 5515 unique observations with 444 parameters varied. Compound 5 has a trans-bridging arrangement of diphosphine ligands and has two carbonyls bound to Ir and three on Os. The carbonyl and phosphine arrangement on Os suggests a trigonal bipyramidal (TBP) arrangement characteristic of Os(0), which then forms a dative Os Ir bond to the Ir(+I) center, giving it a TBP geometry also. The Os-Ir separation of 2.9652 (4) A is at the long end of the range expected for a normal single bond.
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    Dithiophosphinate-bridged ruthenium(I) and ruthenium(II) complexes. The structure of [(Ru2(CO)4(.mu.-S2PMe2)2(PPh3)2].cntdot.1/2CH2Cl2
    (1990) Hilts, Robert; Cowie, Martin
    Replacement of the bridging acetate groups in [Ru2(C0)4(M-02CMe)2(PR'2R")2] (R', R" = Ph, Me) by the dithiophosphinate anions R2PS2‘ (R = Me, Ph) yields a new class of dithiophosphinate-bridged Ru(I) complexes, [Ru2(CO)4(m-S2PR2)2(PR'2R")2]· Although the Ru-Ru bond in these species can be reversibly protonated, it does not react with [Au(PPh3)][BF4], diazomethane, or dimethyl acetylenedicarboxylate. Reaction of the related acetate-bridged species [Ru2(C0)4(M-02CMe)2(NCMe)2] with NaS2PMe2 does not yield the expected dithiophosphinate-bridged product but instead gives the mononuclear species [Ru- (CO)2();2-S2PMe2)2] along with Na2S, Na02CMe, MeCN, and Me2P(S)P(S)Me2. An X-ray structure determination of [Ru2- (CO)4(M-S2PMe2)2(PPh3)2]>1/2CH2Cl2 confirms the dithiophosphinate-bridged formulation and shows a long Ru-Ru separation of 2.9000 (6) A and a twisting about the metal-metal axis by ca. 39°. This compound crystallizes in the monoclinic space group P2,/c with cell parameters a = 15.182 (3) A, b = 18.230 (4) A, c = 18.082 (4) A, ß = 94.23 (2)°, and Z = 4. Refinement has converged at R = 0.054 and /?w = 0.082 on the basis of 5928 unique reflections and 365 parameters varied.
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    Double activation of the geminal carbon−hydrogen bonds in 1,3-butadiene by a diiridium complex
    (2000) Ristic Petrovic, Dusan; Torkelson, Jeffrey R.; Hilts, Robert; McDonald, Robert; Cowie, Martin
    The binuclear complex [Ir2(CH3)(CO)2(dppm)2][CF3SO3] (1) (dppm = Ph2PCH2PPh2) reacts with 1,3-butadiene at ambient temperature over a 48 h period to give the vinylvinylidene-bridged product [Ir2(CH3)(H)(CO)2(μ-H)(μ-CC(H)C(H)CH2)(dppm)2][CF3SO3] (2). At −55 °C the same reactants yield the 1,3-butadiene adduct [Ir2(CH3)(CO)2(μ-η2:η2-H2CC(H)C(H)CH2)(dppm)2][CF3SO3] (3), in which the diolefin binds in an s-trans geometry on one face of the complex. A proposal is advanced rationalizing the conversion of 3 to 2 upon warming.
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    Extraterrestrial organic compounds in our solar system: origins and parent-body alterations
    (2016) Hilts, Robert
    While it is common knowledge that our earth is drenched with an incredibly broad suite of organic compounds, very few of the lay public are aware that many classes of organics, some in very high abundance, are found on most of the planets, moons, planetesimals and comets in our Solar System. In this talk, Dr Hilts will point out where in the Solar System these extraterrestrial organics have been found and which analytical methods were used to identify and quantify these species. During this journey beyond the Earth to the outer reaches of our Solar System he will also describe the most plausible mechanisms that have been proposed for the formation and subsequent chemical alteration of these “outer space organics”.
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    Formation, x-ray structure, and deprotonation of an S,S'-methylene-bridged P2N4S2 ring
    (1992) Chivers, Tristram; Cowie, Martin; Edwards, Mark; Hilts, Robert
    There is an extensive chemistry of binary sulfur-nitrogen (S- N) anions, several of which are shown only in coordination complexes with metals. Although there is polarographic evidence for the formation of S4N4(2-) at low temperatures, this dianion has only been characterized in Ira and Pt5b complexes as a tridentate (N,S,S’) ligand formed by insertion of the metal into an S-N bond of S4N4. Anions of diphosphadithiatetrazocines 1 are unknown, but Pt0 or Pd0 compounds readily undergo oxidative addition with these norganic heterocycles to give ŋ2- S4ZS1-metal complexes.(6)