Victor G. Young

University of Minnesota Duluth, Duluth, Minnesota, United States

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Publications (213)1073.79 Total impact

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    ABSTRACT: Raman spectroscopy is a powerful method for identifying ion-ion interactions, but only if the vibrational band signature for the anion coordination modes can be accurately deciphered. The present study characterizes the PF6- anion P-F Raman symmetric stretching vibrational band for evaluating the PF6-...Li+ cation interactions within LiPF6 crystalline solvates to create a characterization tool for liquid electrolytes. To facilitate this, the crystal structures for two new solvates—(G3)1:LiPF6 and (DEC)2:LiPF6 with triglyme and diethyl carbonate, respectively—are reported. The information obtained from this analysis provides key guidance about the ionic association information which may be obtained from a Raman spectroscopic evaluation of electrolytes containing the LiPF6 salt and aprotic solvents. Of particular note is the overlap of the Raman bands for both solvent-separated ion pair (SSIP) and contact ion pair (CIP) coordination in which the PF6- anions are uncoordinated or coordinated to a single Li+ cation, respectively.
    The Journal of Physical Chemistry C 04/2015; 119(16):8492-8500. DOI:10.1021/acs.jpcc.5b00826 · 4.84 Impact Factor
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    ABSTRACT: Co-crystallization of the high energy material CL-20 and triphenylphosphine oxide yields a 1:2 cocrystal in which CL-20 molecules adopt two different low energy conformations. Hydrogen bonding interactions between the H atoms on the isowurtzitane cage and phosphine oxide are consistent with solvent effects seen in previous crystal growth studies.
    CrystEngComm 01/2015; 17(7). DOI:10.1039/C4CE02285H · 3.86 Impact Factor
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    ABSTRACT: Pseudotetrahedral scorpionato halide complexes [(TpPh,Me)Ni–X] [TpPh,Me = hydrotris(3-phenyl-5-methyl-1-pyrazolyl)borate] were synthesized by metathesis of Tl(TpPh,Me) and NiX2 (X = Cl, Br, I). Pyrazole adducts [(TpPh,Me)Ni(HpzPh,Me)(X)] (X = Cl, I) were also obtained. [(TpPh,Me)Ni–X] (X = Br, I) are isomorphous with previously reported [(TpPh,Me)Ni–Cl], and a new solvated pseudo-polymorph [(TpPh,Me)Ni–Cl]·2CH2Cl2 was found in this work. Ni–X bond lengths correspond to ionic radii of the halide ions, but some variations in Ni–Cl and Ni–N bond lengths are respectively attributed to bending of the chloride from the ideal threefold HB···Ni axis and to the size of the 3-pyrazole substituents. Electronic spectra were rationalized by means of time-dependent (TD) DFT calculations on simplified C3v-symmetric [(Tp)Ni–X] models. Exogenous pyrazole binds to give the pentacoordinate adducts [(TpPh,Me)Ni(HpzPh,Me)(X)] (X = Cl, I). We obtained a crystal structure of the iodide adduct, as well as that of [(TpPh,Me)Ni(HpzPh,Me)(Cl)]·0.5MeCN, isomorphous with a previously reported aquo monosolvate. A hallmark of adduct formation is an intramolecular N–H···X hydrogen bond between the added pyrazole and the adjacent halide ligand, thus giving rise to a strong IR absorption band. The stretching frequency correlates to the N(H)···X separation for the range of known adducts.
    Berichte der deutschen chemischen Gesellschaft 12/2014; 2015(3). DOI:10.1002/ejic.201402897
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    ABSTRACT: The synthesis and solid state structures of homo- and heteroleptic Zr and Ti complexes of 2-(diphenylphosphino)pyrrolide (NP) are reported. The homoleptic Zr(NP)4 (1) and Ti(NP)4 (2) are 8-coordinate in the solid state, and both show extremely long M-P bonds of approximately 2.9 Å. In solution, the phosphine ligands in all complexes are labile: in the titanium complexes phosphine dissociation is rapid at room temperature and equilibrates all phosphines into a single 31P resonance, whereas in the Zr complex 1 dissociation is slower and full equilibration does not occur until 90 °C. The potential to utilize these novel complexes as metalloligands toward other transition metals is discussed.
    Polyhedron 12/2014; 84:111-119. DOI:10.1016/j.poly.2014.06.047 · 2.05 Impact Factor
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    ABSTRACT: Synthesis and characterization of several new pseudotetrahedral arylthiolate complexes [(Tp(Ph,Me))Ni-SAr] (Tp(Ph,Me) = hydrotris{3-phenyl-5-methyl-1-pyrazolyl}borate; Ar = Ph, 2,4,6-(i)Pr3C6H2, C6H4-4-Cl, C6H4-4-Me, C6H4-4-OMe) are reported, including X-ray crystal structures of the first two complexes. With prior results, two series of complexes are spanned, [(Tp(Ph,Me))Ni-S-2,4,6-RC6H2] (R'' = H, Me, (i)Pr) plus the xylyl analogue [(Tp(Ph,Me))Ni-S-2,6-Me2C6H3], as well as [(Tp(Ph,Me))Ni-S-C6H4-4-Y] (Y = Cl, H, Me, OMe), intended to elucidate steric and/or electronic effects on arylthiolate coordination. In contrast to [(Tp(Me,Me))Ni-SAr] analogues that adopt a sawhorse conformation, the ortho-disubstituted complexes show enhanced trigonal and Ni-S-Ar bending, reflecting the size of the 3-pyrazole substituents. Moreover, weakened scorpionate ligation is implied by spectroscopic data. Little spectroscopic effect is observed in the series of para-substituted complexes, suggesting the observed effects are primarily steric in origin. The relatively electron-rich and encumbered complex [(Tp(Ph,Me))Ni-S-2,4,6-(i)Pr3C6H2] behaves uniquely when dissolved in CH3CN, forming a square planar solvent adduct with a bidentate scorpionate ligand, [(κ(2)-Tp(Ph,Me))Ni(NCMe)(S-2,4,6-(i)Pr3C6H2)]. This adduct was isolated and characterized by X-ray crystallography. Single-point DFT and TD-DFT calculations on a simplified [(κ(2)-Tp)Ni(NCMe)(SPh)] model were used to clarify the electronic spectrum of the adduct, and to elucidate differences between Ni-SAr bonding and spectroscopy between pseudotetrahedral and square planar geometries.
    Dalton Transactions 10/2014; 43(46). DOI:10.1039/c4dt02726d · 4.10 Impact Factor
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    ABSTRACT: Cobalt-cobalt and iron-cobalt bonds are investigated in coordination complexes with formally mixed-valent [M2](3+) cores. The trigonal dicobalt tris(diphenylformamidinate) compound, Co2(DPhF)3, which was previously reported by Cotton, Murillo, and co-workers (Inorg. Chim. Acta 1996, 249, 9), is shown to have an energetically isolated, high-spin sextet ground-state by magnetic susceptibility and electron paramagnetic resonance (EPR) spectroscopy. A new tris(amidinato)amine ligand platform is introduced. By tethering three amidinate donors to an apical amine, this platform offers two distinct metal-binding sites. Using the phenyl-substituted variant (abbreviated as L(Ph)), the isolation of a dicobalt homobimetallic and an iron-cobalt heterobimetallic are demonstrated. The new [Co2](3+) and [FeCo](3+) cores have high-spin sextet and septet ground states, respectively. Their solid-state structures reveal short metal-metal bond distances of 2.29 Å for Co-Co and 2.18 Å for Fe-Co; the latter is the shortest distance for an iron-cobalt bond to date. To assign the positions of iron and cobalt atoms as well as to determine if Fe/Co mixing is occurring, X-ray anomalous scattering experiments were performed, spanning the Fe and Co absorption energies. These studies show only a minor amount of metal-site mixing in this complex, and that FeCoL(Ph) is more precisely described as (Fe0.94(1)Co0.06(1))(Co0.95(1)Fe0.05(1))L(Ph). The iron-cobalt heterobimetallic has been further characterized by Mössbauer spectroscopy. Its isomer shift of 0.65 mm/s and quadrupole splitting of 0.64 mm/s are comparable to the related diiron complex, Fe2(DPhF)3. On the basis of spectroscopic data and theoretical calculations, it is proposed that the formal [M2](3+) cores are fully delocalized.
    Inorganic Chemistry 07/2013; 52(16). DOI:10.1021/ic400292g · 4.79 Impact Factor
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    ABSTRACT: A new design strategy is described for chloride ion sensors based on suppression of excited state intramolecular proton transfer in squaramides as a fluorescence "turn on" mechanism.
    Chemical Communications 01/2013; 49(16). DOI:10.1039/c3cc38767d · 6.72 Impact Factor
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    ABSTRACT: Several electrically neutral, highly quadrupolar derivatives of the [closo-B10H10]2− cluster (I) substituted in the apical positions with onium fragments derived from 4-alkoxypyridine, 4-pentylthian, 4-pentylquinuclidine, or dinitrogen were synthesized from the parent cluster in 2–5 steps, and their thermal, structural, photophysical and dielectric properties were investigated. Only derivatives 2, containing thianium and alkoxypyridinium substituents with linear alkyl chains, exhibit liquid crystalline behavior and form a nematic phase. α-Branching of the alkoxy chain leads to marked destabilization of both crystalline and nematic phases, which suggests the importance of polar interactions in phase stabilization of these compounds. Derivatives 2 and 3 with one π and one σ substituent, Q+, exhibit a directional cluster-to-Q charge transfer and increase of the net electric dipole moment to μe = 17.9 D for 2a upon photo-excitation. They are weak fluorophores (Φf = 2–7%). Detailed investigation of 4-heptyloxypyridinium derivative 2b revealed that it exhibits a nematic phase above 100 °C with Δε = +1.3 (130 °C), and a moderate negative solvatochromism. Hyper-Rayleigh scattering measurement gave βHRS = 45 ± 10 × 10−30 esu at 1064 nm. In solutions, and presumably in the melt, it exists as a mixture of interconverting trans and cis isomers at about 4:1 ratio with ΔG298 = 0.82 ± 0.06 kcal mol−1 and ΔG‡298 = 25.3 ± 0.6 kcal mol−1 established by VT NMR methods.
    01/2013; 1(6):1144-1159. DOI:10.1039/C2TC00547F
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    ABSTRACT: 5,6-Dimethylbenzofurazan 1-oxide (Me2BF), C(8)H(8)N(2)O(2), occurs in four polymorphic forms that are polytypes of each other. Each polymorph of Me2BF contains molecules disordered about pseudo-twofold axes and arranged head-to-tail in ribbons, with the ribbons forming approximately planar layers held together by weak C-H...N and C-H...O interactions. Adjacent layers interact in different ways in the different polymorphs. In addition to twinning in the individual polymorphs, four examples of allotwining, that is, oriented overgrowths between different polymorphs, were found.
    Acta crystallographica. Section B, Structural science 10/2012; 68(Pt 5):536-42. DOI:10.1107/S0108768112037457 · 2.10 Impact Factor
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    ABSTRACT: Reaction of two equivalents of K[1,3-(SiMe3)2C3H3] (= K[A′]) with MnCl2 in THF produces the allyl complex A′2Mn(thf)2; if the reaction is conducted in ether, the solvent-free heterometallic manganate species K2MnA′4 is isolated instead. With the related allyl K[1,1′,3-(SiMe3)3C3H2] (= K[A″]), reaction with MnCl2 in THF/TMEDA produces the corresponding adduct A″2Mn(tmeda). In the solid state, both A′2Mn(thf)2 and A″2Mn(tmeda) are monomeric complexes with σ-bonded allyl ligands (Mn–C = 2.174(2) and 2.189(2) Å, respectively). In contrast, K2MnA′4 is a two-dimensional coordination polymer, in which two of the allyl ligands on the Mn cation are σ-bonded (Mn–C = 2.197(6), 2.232(7) Å) and the third is π-bonded (Mn–C = 2.342(7)–2.477(7) Å). Both σ-allyls are π-coordinated to potassium cations, promoting the polymer in two directions; the π-allyl ligand is terminal. Density functional theory (DFT) calculations indicate that isolated high-spin (C3R2H3)2Mn (R = H, SiMe3) complexes would possess π-bound ligands. A mixed hapticity (π-allyl)(σ-allyl)MnE structure would result with the addition of either a neutral ligand (e.g., THF, MeCN) or one that is charged (Cl, H). Both allyl ligands in a bis(allyl)manganese complex are expected to adopt a σ-bonded mode if two THF ligands are added, as is experimentally observed in A′2Mn(thf)2. The geometry of allyl–Mn(II) bonding is readily modified; DFT results predict that [(C3H5)Mn]+ and (C3H5)MnCl should be σ-bonded, but the allyl in (C3H5)MnH is found to exhibit a symmetrical π-bonded arrangement. Some of this behavior is reminiscent of that found in bis(allyl)magnesium chemistry.
    Organometallics 08/2012; 31(17):6131–6138. DOI:10.1021/om300478v · 4.25 Impact Factor
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    David K Ford, Victor G Young, George Barany
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    ABSTRACT: The title compound, C(4)H(6)O(2)S(4), was prepared by repeating, with subtle improvements, a multi-step route originally described by Mott & Barany [J. Chem. Soc. Perkin Trans. 1 (1984) ▶, pp. 2615-2621]. The title compound was obtained for the first time as a crystalline material. The two [(methyl-sulfan-yl)carbon-yl]sulfenyl moieties are essentially perpendic-ular to each other, each approximately planar (r.m.s. deviations of 0.02 and 0.01 Å) and with a C-S-S-C torsion angle = 90.99 (6)°, which compares well with the theoretical value of 90°.
    Acta Crystallographica Section E Structure Reports Online 07/2012; 68(Pt 7):o2102. DOI:10.1107/S1600536812024750 · 0.35 Impact Factor
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    ABSTRACT: Pseudotetrahedral nickel(II) phenolate complexes Tp(R,Me)Ni-OAr (Tp(R,Me) = hydrotris(3-R-5-methylpyrazol-1-yl)borate; R = Ph {1a}, Me {1b}; OAr = O-2,6-(i)Pr(2)C(6)H(3)) were synthesized as models for nickel-substituted copper amine oxidase apoenzyme, which utilizes an N(3)O (i.e., His(3)Tyr) donor set to activate O(2) within its active site for oxidative modification of the tyrosine residue. The bioinspired synthetic complexes 1a,b are stable in dilute CH(2)Cl(2) solutions under dry anaerobic conditions, but they decompose readily upon exposure to O(2) and H(2)O. Aerobic decomposition of 1a yields a range of organic products consistent with formation of phenoxyl radical, including 2,6-diisopropyl-1,4-benzoquinone, 3,5,3',5'-tetraisopropyl-4,4'-diphenodihydroquinone, and 3,5,3',5'-tetraisopropyl-4,4'-diphenoquinone, which requires concurrent O(2) reduction. The dimeric product complex di[hydro{bis(3-phenyl-5-methylpyrazol-1-yl)(3-ortho-phenolato-5-methylpyrazol-1-yl)borato}nickel(II)] (2) was obtained by ortho C-H bond hydroxylation of a 3-phenyl ligand substituent on 1a. In contrast, aerobic decomposition of 1b yields a dimeric complex [Tp(Me,Me)Ni](2)(μ-CO(3)) (3) with unmodified ligands. However, a unique organic product was recovered, assigned as 3,4-dihydro-3,4-dihydroxy-2,6-diisopropylcyclohex-5-enone on the basis of (1)H NMR spectroscopy, which is consistent with dihydroxylation (i.e., addition of H(2)O(2)) across the meta and para positions of the phenol ring. Initial hydrolysis of 1b yields free phenol and the known complex [Tp(Me,Me)Ni(μ-OH)](2), while hydrolysis of 1a yields an uncharacterized intermediate, which subsequently rearranges to the new sandwich complex [(Tp(Ph,Me))(2)Ni] (4). Autoxidation of the released phenol under O(2) was observed, but the reaction was slow and incomplete. However, both 4 and the in situ hydrolysis intermediate derived from 1a react with added H(2)O(2) to form 2. A mechanistic scheme is proposed to account for the observed product formation by convergent oxygenation and hydrolytic autoxidation pathways, and hypothetical complex intermediates along the former were modeled by DFT calculations. All new complexes (i.e., 1a,b and 2-4) were fully characterized by FTIR, (1)H NMR, and UV-vis-NIR spectroscopy and by X-ray crystallography.
    Inorganic Chemistry 06/2012; 51(13):7257-70. DOI:10.1021/ic300551z · 4.79 Impact Factor
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    ABSTRACT: Coordination complexes that pair a zero-valent transition metal (Ni, Co, Fe) and an aluminum(III) center have been prepared. They add to the few examples of structurally characterized metal alanes and are the first reported metallalumatranes. To understand the M-Al interaction and gauge the effect of varying the late metal, the complexes were characterized by X-ray crystallography, electrochemistry, UV-Vis-NIR and NMR spectroscopies, and theoretical calculations. The M-Al bond strength decreases with varying M in the order Ni > Co > Fe.
    Journal of the American Chemical Society 12/2011; 133(51):20724-7. DOI:10.1021/ja2099744 · 11.44 Impact Factor
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    ABSTRACT: The chemistry of polyamino carboxylates and their use as ligands for Ln(3+) ions is of considerable interest from the point of view of the development of new imaging agents. Of particular interest is the chemistry of the macrocyclic ligand 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) and its derivatives. Herein we report that the tetramethylated DOTA derivative, DOTMA, possess several properties that, from an imaging agent development point of view, are more advantageous than those of the parent DOTA. In particular, the Ln(3+) chelates of DOTMA exhibit a marked preference for the monocapped twisted square antiprismatic coordination isomer which imparts more rapid water exchange kinetics on the chelates; τ(M)(298) was determined to be 85 ns for GdDOTMA. Differential analysis of the (17)O R(2ρ) temperature profiles of both GdDOTA and GdDOTMA afforded the τ(M)(298) values for the square (SAP) and twisted square antiprismatic (TSAP) isomers of each chelate that were almost identical: 365 ns (SAP) and 52 ns (TSAP). The origin of this accelerated water exchange in the TSAP isomer appears to be the slightly longer Gd-OH(2) bond distance (2.50 Å) that is observed in the crystal structure of GdDOTMA which crystallizes in the P(2) space group as a TSAP isomer. The Ln(3+) chelates of DOTMA also exhibit high thermodynamic stabilities ranging from log K(ML) = 20.5 for CeDOTMA, 23.5 for EuDOTMA and YbDOTMA comparable to, but a shade lower than, those of DOTA.
    Inorganic Chemistry 08/2011; 50(17):7955-65. DOI:10.1021/ic2012827 · 4.79 Impact Factor
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    ABSTRACT: Controlling the water exchange kinetics of macrocyclic Gd(3+) chelates, a key parameter in the design of improved magnetic resonance imaging (MRI) contrast media, may be facilitated by selecting the coordination geometry of the chelate. The water exchange kinetics of the mono- capped twisted square antiprism (TSAP) being much closer to optimal than those of the mono capped square antiprism (SAP) render the TSAP isomer more desirable for high relaxivity applications. Two systems have been developed that allow for selection of the TSAP coordination geometry in 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA)-type Gd(3+) chelates, both based upon the macrocycle nitrobenzyl cyclen. In this paper we report investigations into the stability and formation of these chelates. Particular focus is given to the production of two regioisomeric chelates during the chelation reaction. These regioisomers are distinguished by having the nitrobenzyl substituent either on a corner or on the side of the macrocyclic ring. The origin of these two regioisomers appears to stem from a conformation of the ligand in solution in which it is hypothesized that pendant arms lie both above and below the plane of the macrocycle. The conformational changes that then result during the formation of the intermediate H(2)GdL(+) chelate give rise to differing positions of the nitrobenzyl substituent depending upon from which face of the macrocycle the Ln(3+) approaches the ligand.
    Inorganic Chemistry 08/2011; 50(17):7966-79. DOI:10.1021/ic2012843 · 4.79 Impact Factor
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    ABSTRACT: Four heterocyclic salts 1a–d were prepared by Ca2+-assisted cyclization of fluoro derivatives 3, and investigated by spectroscopic (NMR and UV), electrochemical, and computational (DFT and MP2) methods. The mechanism for the formation of the cations was investigated at the DFT level of theory. 2-D NMR spectroscopy for 1[ClO4] in DMSO­d6 aided with DFT results permitted the assignment of 1H and 13C NMR signals in cations 1. The molecular and crystal structures for 1a[ClO4] [C13H10ClNO4 triclinic, P−1, a=9.6517(12) Å, b=11.0470(13) Å, c=12.2373(15) Å, α=67.615(1)°, β=78.845(2)°, γ=87.559(2)°; V=1183.0(2) Å3, Z=4] and 1d[ClO4] [C12H9ClN2O4 triclinic, P−1, a=5.9525(6) Å, b=8.3141(9) Å, c=12.2591(13) Å, α=73.487(1)°, β=83.814(1)°, γ=83.456(1)°; V=576.07(10) Å3, Z=2] were determined by X-ray crystallography and compared with results of DFT and MP2 calculations. Electrochemical analysis gave the reduction potential order (1b>1c∼1d>1a), which is consistent with computational results.
    Tetrahedron 05/2011; 67(19):3317-3327. DOI:10.1016/j.tet.2011.03.023 · 2.82 Impact Factor
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    ABSTRACT: Five 2-azinyl-2H-benzotriazoles (azinyl=2-pyridinyl, 2-pyrazinyl, 2-pyrimidinyl, 6-methoxy-3-pyridazinyl, 5-methyl-2-pyridinyl were prepared and characterized as bidentate ligands. The electronic structure of these and related heterocycles was investigated spectroscopically and computationally (TD-DFT). They were tested at the B3LYP/6-31++G(d,p)//B3LYP/6-31G(d,p) level of theory as ligands for MgH2, which permitted the elucidation of trends in complex formation, its geometry as a function of the ring structure, and the number and position of the nitrogen atoms in the azine ring. A Ru2+ complex 7a-Ru with 2-pyridinyl-2H-benzotriazole (7a) and two bpy ligands was prepared and characterized structurally, spectroscopically and electrochemically. The results were compared to those for similar complexes and discussed in the context of computational results for MgH2 complexes.
    Polyhedron 04/2011; 30(7):1339-1348. DOI:10.1016/j.poly.2011.02.023 · 2.05 Impact Factor
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    ABSTRACT: The complex Tp(Ph,Me)NiS(2)CNMe(2) [Tp(Ph,Me) = hydrotris(3-phenyl-5-methyl-1-pyrazolyl)borate] features a bioinspired N(3)S(2) ligand set supporting a five-coordinate, trigonally distorted square-pyramidal geometry in the solid state. Spin crossover of Ni(II) was demonstrated by temperature-dependent X-ray crystallography and magnetic susceptibility measurements. The crystal lattice contains two independent molecules (i.e., Ni1 and Ni2). At 293 K, the observed bond lengths and susceptibility are consistent with high-spin (S = 1) Ni(II), and both molecules exhibit relatively short axial Ni-N bonds and long Ni-N and Ni-S equatorial bonds. At 123 K, the Ni1 complex remains high-spin, but the Ni2 molecule substantially crosses to a structurally distinct diamagnetic (S = 0) state with significant elongation of the axial Ni-N bond and offsetting contraction of the equatorial bonds. The temperature-dependent susceptibility data were fit to a spin equilibrium at Ni2 [ΔH° = 1.13(2) kcal/mol and ΔS° = +7.3(1) cal mol(-1) K(-1)] consistent with weak coupling to lattice effects. Cooling below 100 K results in crossover of the Ni1 complex.
    Journal of the American Chemical Society 03/2011; 133(15):5644-7. DOI:10.1021/ja110890v · 11.44 Impact Factor
  • Jason A Wiles, Steven H Bergens, Victor G Young
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    ABSTRACT: Reaction of [Ru((R)-BINAP)(H)(MeCN)n(acetone)3–n](BF4) (where n = 0–3) (2) with 1 equiv of the olefin substrate methyl α-acetamidoacrylate (MAA) in acetone at room temperature immediately generated a mixture (72:28) of two diastereomers of the complex [Ru((R)-BINAP)(MeCN)(MAA(H))](BF4) (3). The olefin–hydride insertion reaction between 2 and MAA to generate 3 was regioselective, with transfer of the hydride to the β-olefinic carbon and transfer of ruthenium to the α-carbon in both diastereomers of 3. The two diastereomers of 3 differ by the absolute configuration at the α-carbon of MAA(H) ((SCα)-3 and (RCα)-3). The absolute configuration of the major ((SCα)-3) diastereomer was determined by X-ray diffraction in conjunction with NMR spectroscopic data. Protonolysis of the ruthenium–carbon bond in 3 and in the methyl α-acetamidocinnamate (MAC) analog ([Ru((R)-BINAP)(MeCN)((S)- MAC(H))](BF4) ((SCα)-4)) by addition of 2 equiv HBF4·Et2O in CH2Cl2 at room temperature was not stereospecific and did not occur with β-hydride elimination from the methyl or benzyl groups.Key words: ruthenium, BINAP, enantioselective, hydrogenation, catalysis.
    Canadian Journal of Chemistry 02/2011; 79(5-6):1019-1025. DOI:10.1139/cjc-79-5-6-1019 · 1.01 Impact Factor
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    ABSTRACT: A comparative study of the reactivity of dinitrogen acids [closo-1-CB(9)H(8)-1-COOH-10-N(2)] (3[10]) and [closo-1-CB(9)H(8)-1-COOH-6-N(2)] (3[6]) was conducted by diazotization of a mixture of amino acids [closo-1-CB(9)H(8)-1-COOH-6-NH(3)] (1[6]) and [closo-1-CB(9)H(8)-1-COOH-10-NH(3)] (1[10]) with NO(+)BF(4)(-) in the presence of a heterocyclic base (pyridine, 4-methoxypyridine, 2-picoline, or quinoline). The 10-amino acid 1[10] formed an isolable stable 10-dinitrogen acid 3[10], while the 6-dinitrogen carboxylate 3[6](-) reacted in situ, giving products of N-substitution at the B6 position with the heterocyclic solvent (4[6]). The molecular and crystal structures for pyridinium acid 4[6]a were determined by X-ray crystallography. The electronic structures and reactivity of the 6-dinitrogen derivatives of the {1-CB(9)} cluster were assessed computationally at the B3LYP/6-31G(d,p) and MP2/6-31G(d,p) levels of theory and compared to those of the 10-dinitrogen, 2-dinitrogen, and 1-dinitrogen analogues.
    Inorganic Chemistry 02/2011; 50(6):2654-60. DOI:10.1021/ic102557s · 4.79 Impact Factor

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5k Citations
1,073.79 Total Impact Points


  • 1995–2015
    • University of Minnesota Duluth
      • Department of Chemistry and Biochemistry
      Duluth, Minnesota, United States
  • 2013–2014
    • University of Minnesota Twin Cities
      • Department of Chemistry
      Minneapolis, Minnesota, United States
  • 2011
    • University of Alberta
      • Department of Chemistry
      Edmonton, Alberta, Canada
  • 1996–2011
    • Saint Mary's University of Minnesota
      • Chemistry
      Minneapolis, Minnesota, United States
    • Universität Basel
      Bâle, Basel-City, Switzerland
    • University of Guelph
      • Department of Chemistry
      XIA, Ontario, Canada
  • 1991–2010
    • Iowa State University
      • • Department of Materials Science and Engineering
      • • Department of Chemistry
      Ames, Iowa, United States
  • 2005
    • Stanford University
      • Department of Chemistry
      Palo Alto, California, United States
    • Dow Corning Corporation
      Seneffe, Walloon Region, United States
  • 2000–2005
    • Arizona State University
      • Department of Chemistry and Biochemistry
      Mesa, AZ, United States
    • University of British Columbia - Vancouver
      • Department of Chemistry
      Vancouver, British Columbia, Canada
    • Macalester College
      • Department of Chemistry
      Saint Paul, MN, United States
    • University of Barcelona
      Barcino, Catalonia, Spain
  • 2001–2004
    • University of Kansas
      • Department of Chemistry
      Lawrence, KS, United States
    • University of Wisconsin - Eau Claire
      Eau Claire, Wisconsin, United States
  • 2003
    • Ewha Womans University
      Sŏul, Seoul, South Korea
    • Universidade Federal do Rio Grande do Sul
      • Institute of Chemistry
      Pôrto de São Francisco dos Casaes, Rio Grande do Sul, Brazil
    • Stony Brook University
      • Department of Chemistry
      Stony Brook, New York, United States
    • Murray State University
      • Department of Chemistry
      Kentucky, United States
  • 1998–2000
    • Vanderbilt University
      • Department of Chemistry
      Nashville, MI, United States
    • University of Michigan
      • Department of Chemistry
      Ann Arbor, Michigan, United States
  • 1997
    • University of Delaware
      • Department of Chemistry and Biochemistry
      Newark, DE, United States