Hilary Eppley | DePauw University (original) (raw)
Papers by Hilary Eppley
Skip to main content Digital Commons @ Hope College. ...
Cur Quarterly Web Vignette, 2013
Edulearn09 Proceedings, 2009
The Journal of Physical Chemistry, 1991
... J. N. Spencer,; Travis F. Ganunis, Abe I. Zafar, Christine M. Salata, Sunita Gupta, Shaym Pup... more ... J. N. Spencer,; Travis F. Ganunis, Abe I. Zafar, Christine M. Salata, Sunita Gupta, Shaym Puppala,Hilary J. Eppley, James L. Ealy, and Claude H. Yoder Department of Chemistry, Franklin & Marshall College, Lancaster ... 3) Yoder, C. H.; Mokrynka, D.; Coley, S. M.; Otter, JC; Haines ...
Journal of the Chemical Society, Chemical Communications, 1994
ABSTRACT Reduction of the 8MnIII,4MnIV complex [Mn12O12(O2CEt)16(H2O)3] with PPh4l in CH2Cl2 lead... more ABSTRACT Reduction of the 8MnIII,4MnIV complex [Mn12O12(O2CEt)16(H2O)3] with PPh4l in CH2Cl2 leads to isolation of (PPh4)[Mn12O12(O2CEt)16(H2O)4](3) whose crystal structure shows that the added electron is localized on a formerly MnIII ion to give a trapped-valence MnII,7MnIII,4MnIV situation; DC and AC magnetic susceptibility studies show that 3 has an S= 19/2 ground state and that it displays a superparamagnet-like non-zero, frequency-dependent, out-of-phase response in the AC susceptibility behaviour that is extremely unusual for a molecular species and unique for an ionic species.
ACS Symposium Series, 2010
The Journal of Physical Chemistry B, 1998
The nature of the Mn oxidation states involved in photosynthetic oxygen evolution has remained co... more The nature of the Mn oxidation states involved in photosynthetic oxygen evolution has remained controversial, despite intense study by X-ray absorption and electron paramagnetic resonance spectroscopy. As an alternative approach, high-resolution K X-ray fluorescence spectra have been recorded on the dark-adapted S 1 state and the hydroquinone-reduced state of the oxygen-evolving complex in photosystem II. By comparison of the K chemical shifts with those of appropriate model compounds, the S 1 state of photosystem II is found to contain equal amounts of Mn(III) and Mn(IV). In the hydroquinone-reduced sample, a significant fraction of the Mn is reduced to Mn(II). The results are compatible with models involving conversion of Mn(III) 2 Mn-(IV) 2 to Mn(II) 2 Mn(IV) 2 clusters.
Molecular Crystals and Liquid Crystals Science and Technology. Section A. Molecular Crystals and Liquid Crystals, 1997
... (b) PCE Stamp, EM Chudnos-vsky and B. Barbara Znt. J. Md. Phys., B6, 1355 (1992). (a) D. Loss... more ... (b) PCE Stamp, EM Chudnos-vsky and B. Barbara Znt. J. Md. Phys., B6, 1355 (1992). (a) D. Loss, DP DiVincenzo, G. Carinstein, DD Awschalom and JF Smyth, Physicu B, 189, 189 (1993). (b) DD Awschalom, DP DiVincenzo and J. F. Smyth, Science, 258,414 (1992). ...
Molecular Crystals and Liquid Crystals Science and Technology. Section A. Molecular Crystals and Liquid Crystals, 1997
The syntheses and characterization of three new dodecanuclear manganese complexes with the compos... more The syntheses and characterization of three new dodecanuclear manganese complexes with the composition [Mn12012(OzCRh6(HzO)4] are reported where R is %Cl (1), %CH3
Molecular Crystals and Liquid Crystals Science and Technology. Section A. Molecular Crystals and Liquid Crystals, 1995
A structural and magnetic comparison is presented for a number of high nuclearity, higher oxidati... more A structural and magnetic comparison is presented for a number of high nuclearity, higher oxidation state manganese complexes with similar ligation environments. The complexes considered are hepta-, octa-, ennea-, deca-, and dodecanuclear and contain only Mn, except for the dodecanuclear complexes, which are mixed valence (Mn 8Mn 4). The ground state spins of these complexes range from very low to
Journal of the American Chemical Society, 1995
Nanoscale magnetic materials are the focus of considerable research because they are expected to ... more Nanoscale magnetic materials are the focus of considerable research because they are expected to exhibit unusual proper-ties.' Such nanoscale magnetic materials can be prepared either by fragmenting bulk ferromagnets or by building up molecules ... Indiana University. * ...
Journal of the American Chemical Society, 2002
We report the syntheses of the photochemically labile 9-diazo-4,5-diazafluorene (1) framework and... more We report the syntheses of the photochemically labile 9-diazo-4,5-diazafluorene (1) framework and the corresponding Cu(9-diazo-4,5-diazafluorene)2(NO3)2 compound (2). The X-ray structure of 2 reveals a 6-coordinate, tetragonal geometry with one nitrogen donor of an asymmetrically chelated diazafluorene in the equatorial position and the other defining the weak Jahn-Teller axis. The nitrate counterions bind in a monodentate fashion in the equatorial plane to complete the coordination sphere. Extended Hü ckel calculations reveal that the unusual solid-state structure derives from the enlarged bite angle of the fluorene skeleton and steric interactions between the adjacent hydrogen atoms in the higher energy (0.45 eV) symmetrically coordinated state. This is in contrast to Cu(py)4(NO3)2 which is 1.3 eV more stable with the nitrate counterions bound along the Jahn-Teller axis. Electron paramagnetic resonance (EPR) studies in solution reveal that the nitrates dissociate to yield 6-coordinate CuN2X2N2′ structures with either a bound chloride ion (gx ) 2.10, gy ) 2.04, gz ) 2.23, Az ) 177 × 10 -4 cm -1 ) or a mixture of counterion and solvent (gxa ) 2.05, gya ) 2.06, gza ) 2.29, Aza ) 170 × 10 -4 cm -1 ; gxb ) 2.07, gyb ) 2.08, gzb ) 2.34, Azb ) 155 × 10 -4 cm -1 ). Photolyses of 1 and 2 indicate loss of N2 and formation of either carbene (|D/hc| ) 0.408 cm -1 , |E/hc| ) 0.0292 cm -1 ) or Cu(I)-L •+ (S ) 1 /2, g ) 2.0019) intermediates, which are identified by EPR, UV-vis, and time-dependent density functional theory methods. The results illustrate the important role redox active transition metals play in determining the nature of fundamental metal-ligand radical intermediates.
Journal of Organometallic Chemistry, 1990
Thermodynamic parameters for adduct formation by R,SnX,_,, where R is methyl, ethyl, or butyl, an... more Thermodynamic parameters for adduct formation by R,SnX,_,, where R is methyl, ethyl, or butyl, and X is Cl, Br, or I, with tributylphosphine (TBP) in benzene and chlorobenzene solvents are reported. These data are combined with previously reported data for the same systems with triphenylphosphine oxide (TPPO). The enthalpies of adduct formation generally increase in the order Cl < Br < I thus producing a reversal of the acid-strengthening effects due to substitution of more electronegative elements_ Equilibrium constants, however, increase in the order I < Br < Cl, indicating a dominance of the entropy term for formation of these organotin halide adducts with TBP and TPPO. 0022-328X/90/%03.50 0 1990 -Elsevier Sequoia S.A.
Journal of Organometallic Chemistry, 1992
Abstract Proton, carbon-13, nitrogen-15, fluorine-19, and silicon-29 NMR chemical shifts and coup... more Abstract Proton, carbon-13, nitrogen-15, fluorine-19, and silicon-29 NMR chemical shifts and coupling constants are reported for nine N-substituted anilines of the type XC 6 H 4 N (H) Y, where X= H and F, and Y= Si (CH 3) 3, Ge (CH 3) 3, Sn (CH 3) 3, and P (BH 3)(CH 3) 2, ...
Skip to main content Digital Commons @ Hope College. ...
Cur Quarterly Web Vignette, 2013
Edulearn09 Proceedings, 2009
The Journal of Physical Chemistry, 1991
... J. N. Spencer,; Travis F. Ganunis, Abe I. Zafar, Christine M. Salata, Sunita Gupta, Shaym Pup... more ... J. N. Spencer,; Travis F. Ganunis, Abe I. Zafar, Christine M. Salata, Sunita Gupta, Shaym Puppala,Hilary J. Eppley, James L. Ealy, and Claude H. Yoder Department of Chemistry, Franklin & Marshall College, Lancaster ... 3) Yoder, C. H.; Mokrynka, D.; Coley, S. M.; Otter, JC; Haines ...
Journal of the Chemical Society, Chemical Communications, 1994
ABSTRACT Reduction of the 8MnIII,4MnIV complex [Mn12O12(O2CEt)16(H2O)3] with PPh4l in CH2Cl2 lead... more ABSTRACT Reduction of the 8MnIII,4MnIV complex [Mn12O12(O2CEt)16(H2O)3] with PPh4l in CH2Cl2 leads to isolation of (PPh4)[Mn12O12(O2CEt)16(H2O)4](3) whose crystal structure shows that the added electron is localized on a formerly MnIII ion to give a trapped-valence MnII,7MnIII,4MnIV situation; DC and AC magnetic susceptibility studies show that 3 has an S= 19/2 ground state and that it displays a superparamagnet-like non-zero, frequency-dependent, out-of-phase response in the AC susceptibility behaviour that is extremely unusual for a molecular species and unique for an ionic species.
ACS Symposium Series, 2010
The Journal of Physical Chemistry B, 1998
The nature of the Mn oxidation states involved in photosynthetic oxygen evolution has remained co... more The nature of the Mn oxidation states involved in photosynthetic oxygen evolution has remained controversial, despite intense study by X-ray absorption and electron paramagnetic resonance spectroscopy. As an alternative approach, high-resolution K X-ray fluorescence spectra have been recorded on the dark-adapted S 1 state and the hydroquinone-reduced state of the oxygen-evolving complex in photosystem II. By comparison of the K chemical shifts with those of appropriate model compounds, the S 1 state of photosystem II is found to contain equal amounts of Mn(III) and Mn(IV). In the hydroquinone-reduced sample, a significant fraction of the Mn is reduced to Mn(II). The results are compatible with models involving conversion of Mn(III) 2 Mn-(IV) 2 to Mn(II) 2 Mn(IV) 2 clusters.
Molecular Crystals and Liquid Crystals Science and Technology. Section A. Molecular Crystals and Liquid Crystals, 1997
... (b) PCE Stamp, EM Chudnos-vsky and B. Barbara Znt. J. Md. Phys., B6, 1355 (1992). (a) D. Loss... more ... (b) PCE Stamp, EM Chudnos-vsky and B. Barbara Znt. J. Md. Phys., B6, 1355 (1992). (a) D. Loss, DP DiVincenzo, G. Carinstein, DD Awschalom and JF Smyth, Physicu B, 189, 189 (1993). (b) DD Awschalom, DP DiVincenzo and J. F. Smyth, Science, 258,414 (1992). ...
Molecular Crystals and Liquid Crystals Science and Technology. Section A. Molecular Crystals and Liquid Crystals, 1997
The syntheses and characterization of three new dodecanuclear manganese complexes with the compos... more The syntheses and characterization of three new dodecanuclear manganese complexes with the composition [Mn12012(OzCRh6(HzO)4] are reported where R is %Cl (1), %CH3
Molecular Crystals and Liquid Crystals Science and Technology. Section A. Molecular Crystals and Liquid Crystals, 1995
A structural and magnetic comparison is presented for a number of high nuclearity, higher oxidati... more A structural and magnetic comparison is presented for a number of high nuclearity, higher oxidation state manganese complexes with similar ligation environments. The complexes considered are hepta-, octa-, ennea-, deca-, and dodecanuclear and contain only Mn, except for the dodecanuclear complexes, which are mixed valence (Mn 8Mn 4). The ground state spins of these complexes range from very low to
Journal of the American Chemical Society, 1995
Nanoscale magnetic materials are the focus of considerable research because they are expected to ... more Nanoscale magnetic materials are the focus of considerable research because they are expected to exhibit unusual proper-ties.' Such nanoscale magnetic materials can be prepared either by fragmenting bulk ferromagnets or by building up molecules ... Indiana University. * ...
Journal of the American Chemical Society, 2002
We report the syntheses of the photochemically labile 9-diazo-4,5-diazafluorene (1) framework and... more We report the syntheses of the photochemically labile 9-diazo-4,5-diazafluorene (1) framework and the corresponding Cu(9-diazo-4,5-diazafluorene)2(NO3)2 compound (2). The X-ray structure of 2 reveals a 6-coordinate, tetragonal geometry with one nitrogen donor of an asymmetrically chelated diazafluorene in the equatorial position and the other defining the weak Jahn-Teller axis. The nitrate counterions bind in a monodentate fashion in the equatorial plane to complete the coordination sphere. Extended Hü ckel calculations reveal that the unusual solid-state structure derives from the enlarged bite angle of the fluorene skeleton and steric interactions between the adjacent hydrogen atoms in the higher energy (0.45 eV) symmetrically coordinated state. This is in contrast to Cu(py)4(NO3)2 which is 1.3 eV more stable with the nitrate counterions bound along the Jahn-Teller axis. Electron paramagnetic resonance (EPR) studies in solution reveal that the nitrates dissociate to yield 6-coordinate CuN2X2N2′ structures with either a bound chloride ion (gx ) 2.10, gy ) 2.04, gz ) 2.23, Az ) 177 × 10 -4 cm -1 ) or a mixture of counterion and solvent (gxa ) 2.05, gya ) 2.06, gza ) 2.29, Aza ) 170 × 10 -4 cm -1 ; gxb ) 2.07, gyb ) 2.08, gzb ) 2.34, Azb ) 155 × 10 -4 cm -1 ). Photolyses of 1 and 2 indicate loss of N2 and formation of either carbene (|D/hc| ) 0.408 cm -1 , |E/hc| ) 0.0292 cm -1 ) or Cu(I)-L •+ (S ) 1 /2, g ) 2.0019) intermediates, which are identified by EPR, UV-vis, and time-dependent density functional theory methods. The results illustrate the important role redox active transition metals play in determining the nature of fundamental metal-ligand radical intermediates.
Journal of Organometallic Chemistry, 1990
Thermodynamic parameters for adduct formation by R,SnX,_,, where R is methyl, ethyl, or butyl, an... more Thermodynamic parameters for adduct formation by R,SnX,_,, where R is methyl, ethyl, or butyl, and X is Cl, Br, or I, with tributylphosphine (TBP) in benzene and chlorobenzene solvents are reported. These data are combined with previously reported data for the same systems with triphenylphosphine oxide (TPPO). The enthalpies of adduct formation generally increase in the order Cl < Br < I thus producing a reversal of the acid-strengthening effects due to substitution of more electronegative elements_ Equilibrium constants, however, increase in the order I < Br < Cl, indicating a dominance of the entropy term for formation of these organotin halide adducts with TBP and TPPO. 0022-328X/90/%03.50 0 1990 -Elsevier Sequoia S.A.
Journal of Organometallic Chemistry, 1992
Abstract Proton, carbon-13, nitrogen-15, fluorine-19, and silicon-29 NMR chemical shifts and coup... more Abstract Proton, carbon-13, nitrogen-15, fluorine-19, and silicon-29 NMR chemical shifts and coupling constants are reported for nine N-substituted anilines of the type XC 6 H 4 N (H) Y, where X= H and F, and Y= Si (CH 3) 3, Ge (CH 3) 3, Sn (CH 3) 3, and P (BH 3)(CH 3) 2, ...