Victor G. Young

University of Minnesota Duluth, Duluth, MN, United States

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Publications (162)690.85 Total impact

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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; · 4.59 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; · 6.38 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.
    J. Mater. Chem. C. 01/2013; 1(6):1144-1159.
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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. · 1.80 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. · 4.15 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. · 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. · 4.59 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. · 10.68 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. · 4.59 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. · 4.59 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. · 10.68 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. · 4.59 Impact Factor
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    ABSTRACT: The diphosphine 4,6-bis(3-diisopropylphosphinophenyl)dibenzofuran (abbreviated as (iPr)DPDBFphos) was prepared and studied for its potential as a trans-chelating ligand in transition-metal coordination complexes. In the rhodium norbornadiene complex [((iPr)DPDBFphos)Rh(NBD)]BF(4), which has been characterized with multinuclear NMR spectroscopy, X-ray crystallography, and electrochemical studies, the ligand binds in cis fashion. In the bis(acetonitrile) complexes of rhodium and palladium [((iPr)DPDBFphos)M(CH(3)CN)(2)](BF(4))(n) (M = Rh, Pd; n = 1, 2), the ligand adopts a trans coordination geometry. Density functional theory (DFT, M06-L) calculations predict that the trans conformer is energetically more favorable than the cis by 3.5 kcal/mol. Cyclic voltammograms of the bis(acetonitrile) Pd(II) and Rh(I) complexes contain reversible and quasi-reversible reduction events, respectively, which are preliminarily assigned as metal-based redox reactions.
    Inorganic Chemistry 02/2011; 50(6):2545-52. · 4.59 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. 01/2011; 67(19):3317-3327.
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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 01/2011; 30(7):1339-1348. · 2.05 Impact Factor
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    ABSTRACT: [Fe(IV)(O)(TMG(3)tren)](2+) (1; TMG(3)tren = 1,1,1-tris{2-[N(2)-(1,1,3,3-tetramethylguanidino)]ethyl}amine) is a unique example of an isolable synthetic S = 2 oxoiron(IV) complex, which serves as a model for the high-valent oxoiron(IV) intermediates observed in nonheme iron enzymes. Congruent with DFT calculations predicting a more reactive S = 2 oxoiron(IV) center, 1 has a lifetime significantly shorter than those of related S = 1 oxoiron(IV) complexes. The self-decay of 1 exhibits strictly first-order kinetic behavior and is unaffected by solvent deuteration, suggesting an intramolecular process. This hypothesis was supported by ESI-MS analysis of the iron products and a significant retardation of self-decay upon use of a perdeuteromethyl TMG(3)tren isotopomer, d(36)-1 (KIE = 24 at 25 degrees C). The greatly enhanced thermal stability of d(36)-1 allowed growth of diffraction quality crystals for which a high-resolution crystal structure was obtained. This structure showed an Fe horizontal lineO unit (r = 1.661(2) A) in the intended trigonal bipyramidal geometry enforced by the sterically bulky tetramethylguanidinyl donors of the tetradentate tripodal TMG(3)tren ligand. The close proximity of the methyl substituents to the oxoiron unit yielded three symmetrically oriented short C-D...O nonbonded contacts (2.38-2.49 A), an arrangement that facilitated self-decay by rate-determining intramolecular hydrogen atom abstraction and subsequent formation of a ligand-hydroxylated iron(III) product. EPR and Mossbauer quantification of the various iron products, referenced against those obtained from reaction of 1 with 1,4-cyclohexadiene, allowed formulation of a detailed mechanism for the self-decay process. The solution of this first crystal structure of a high-spin (S = 2) oxoiron(IV) center represents a fundamental step on the path toward a full understanding of these pivotal biological intermediates.
    Journal of the American Chemical Society 06/2010; 132(25):8635-44. · 10.68 Impact Factor
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    Lindsay M Hinkle, Victor G Young, Kent R Mann
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    ABSTRACT: The first structure report of trichlorido[4'-(p-tolyl)-2,2':6',2''-terpyridine]iridium(III) dimethyl sulfoxide solvate, [IrCl(3)(C(22)H(17)N(3))] x C(2)H(6)OS, (I), is presented, along with a higher-symmetry setting of previously reported bis[4'-(p-tolyl)-2,2':6',2''-terpyridine]iridium(III) tris(hexafluoridophosphate) acetonitrile disolvate, [Ir(C(22)H(17)N(3))(2)](PF(6))(3) x 2 C(2)H(3)N, (II) [Yoshikawa, Yamabe, Kanehisa, Kai, Takashima & Tsukahara (2007). Eur. J. Inorg. Chem. pp. 1911-1919]. For (I), the data were collected with synchrotron radiation and the dimethyl sulfoxide solvent molecule is disordered over three positions, one of which is an inversion center. The previously reported structure of (II) is presented in the more appropriate C2/c space group. The iridium complex and one PF(6)(-) anion lie on twofold axes in this structure, making half of the molecule unique.
    Acta Crystallographica Section C Crystal Structure Communications 03/2010; 66(Pt 3):m62-4. · 0.78 Impact Factor
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    ABSTRACT: Amino acid [closo-1-CB(9)H(8)-1-COO-10-NH(3)](-) (4) was prepared by amination of iodo acid [closo-1-CB(9)H(8)-1-COOH-10-I](-) (1) with LiHMDS in a practical and reproducible manner. The apparent dissociation constants, pK(2) = 5.6 and pK(1) > 11, were measured for 4[NMe(4)] in 50% aq. EtOH. Diazotization of 4 with NO(+)PF(6)(-) under mildly basic conditions afforded stable dinitrogen acid [closo-1-CB(9)H(8)-1-COOH-10-N(2)] (5). Activation parameters (DeltaH(++) = 33.9 +/- 1.4 kcal mol(-1) and DeltaS(++) = 10 +/- 3.5 cal mol(-1) K(-1)) for thermolysis of its methyl ester [closo-1-CB(9)H(8)-1-COOMe-10-N(2)] (11) in PhCN were established, and the heterolysis of the B-N bond is believed to be the rate-determining step. Electrochemical analysis showed a partially reversible reduction process for 11 (E(1/2)(red) = -1.03 V) and 5(-) (E(1/2)(red) = -1.21 V), which are more cathodic than reduction of [closo-1-CB(9)H(9)-1-N(2)] (17). The dinitrogen acid 5 was reacted with pyridine and N,N-dimethylthioformamide, to form pyridine acid 6 and protected mercapto acid 7, respectively, through a boronium ylide intermediate 18. Compound 7 was converted to sulfonium acid 8. The molecular and crystal structures for 5 [C(2)H(9)B(9)N(2)O(2) monoclinic, P2(1)/n, a = 7.022(2) A, b = 11.389(4) A, c = 12.815(4) A, beta = 96.212(5) degrees ; V = 1018.8(6) A(3), Z = 4,], 6 [C(7)H(14)B(9)NO(2), monoclinic, P2(1)/n, a = 14.275(4) A, b = 12.184(3) A, c = 30.538(8) A, beta = 95.377(4) degrees ; V = 5288(3) A(3), Z = 16], and 8 [C(7)H(19)B(9)O(2)S, monoclinic, P2(1)/c, a = 15.988(5) A, b = 19.377(6) A, c = 9.655(3) A, beta = 98.348(5) degrees; V = 2959.4(16) A(3), Z = 8] were determined by X-ray crystallography and compared with results of density functional theory (DFT) and MP2 calculations. Electronic structures of 5, 6, and related species were elucidated with electronic spectroscopy and assessed computationally at the B3LYP/6-31G(d,p), MP2/6-31G(d,p), and ZINDO//MP2 levels of theory.
    Inorganic Chemistry 02/2010; 49(3):1166-79. · 4.59 Impact Factor
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    ABSTRACT: Photoactive analogs of farnesyl diphosphate (FPP) are useful probes in studies of enzymes that employ this molecule as a substrate. Here, we describe the preparation and properties of two new FPP analogs that contain diazotrifluoropropanoyl photophores linked to geranyl diphosphate via amide or ester linkages. The amide-linked analog (3) was synthesized in 32P-labeled form from geraniol in seven steps. Experiments with Saccharomyces cerevisiae protein farnesyltransferase (ScPFTase) showed that 3 is an alternative substrate for the enzyme. Photolysis experiments with [(32)P]3 demonstrate that this compound labels the beta-subunits of both farnesyltransferase and geranylgeranyltransferase (types 1 and 2). However, the amide-linked probe 3 undergoes a rearrangement to a photochemically unreactive isomeric triazolone upon long term storage making it inconvenient to use. To address this stability issue, the ester-linked analog 4 was prepared in six steps from geraniol. Computational analysis and X-ray crystallographic studies suggest that 4 binds to protein farnesyl transferase (PFTase) in a similar fashion as FPP. Compound 4 is also an alternative substrate for PFTase, and a 32P-labeled form selectively photocrosslinks the beta-subunit of ScPFTase as well as E. coli farnesyldiphosphate synthase and a germacrene-producing sesquiterpene synthase from Nostoc sp. strain PCC7120 (a cyanobacterial source). Finally, nearly exclusive labeling of ScPFTase in crude E. coli extract was observed, suggesting that [32P]4 manifests significant selectivity and should hence be useful for identifying novel FPP-utilizing enzymes in crude protein preparations.
    Chemical Biology &amp Drug Design 01/2010; 75(1):51-67. · 2.47 Impact Factor
  • Andrew J. Thom, Victor G. Young, Mufit Akinc
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    ABSTRACT: ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
    ChemInform 01/2010; 31(11).

Publication Stats

1k Citations
690.85 Total Impact Points

Institutions

  • 1996–2013
    • University of Minnesota Duluth
      • Department of Chemistry and Biochemistry
      Duluth, MN, United States
    • University of Minnesota Twin Cities
      • • Department of Chemistry
      • • Department of Pharmaceutics
      Minneapolis, Minnesota, United States
    • Saint Mary's University of Minnesota
      • Chemistry
      Minneapolis, Minnesota, United States
  • 2008–2012
    • Ohio University
      • Department of Chemistry and Biochemistry
      Athens, OH, United States
  • 1998–2011
    • Vanderbilt University
      • Department of Chemistry
      Nashville, MI, United States
  • 2010
    • Iowa State University
      • Department of Materials Science and Engineering
      Ames, Iowa, United States
  • 2001–2005
    • Arizona State University
      • Department of Chemistry and Biochemistry
      Mesa, AZ, United States
    • University of the South
      • Department of Chemistry
      Sewanee, TN, United States
  • 2004
    • University of Wisconsin - Eau Claire
      Eau Claire, Wisconsin, United States
  • 2000–2004
    • University of Kansas
      • • Department of Chemistry
      • • Department of Pharmaceutical Chemistry
      Lawrence, KS, United States
  • 2003
    • Murray State University
      • Department of Chemistry
      Murray, KY, United States
  • 2002
    • GlaxoSmithKline plc.
      Londinium, England, United Kingdom
  • 1999
    • Monsanto Company
      Saint Louis, Michigan, United States
  • 1997
    • University of Delaware
      • Department of Chemistry and Biochemistry
      Newark, DE, United States