@article {960,
	title = {Poly[(2,2 {\textquoteright}-bipyridine)tetrakis(imidazolato)diiron(II)]: Structural and spin-state phase transitions and low-temperature magnetic ordering in a unique 2-dimensional material},
	journal = {Inorganic Chemistry},
	volume = {43},
	number = {7},
	year = {2004},
	note = {ISI Document Delivery No.: 808QLTimes Cited: 9Cited Reference Count: 31},
	month = {Apr},
	pages = {2330-2339},
	type = {Article},
	abstract = {Poly[(2,2{\textquoteright}-bipyridine)tetrakis(imidazolato)diiron(II)] was synthesized by the reaction of ferrocene with imidazole in an excess of 2,2{\textquoteright}- bipyridine in a Carius tube at 130degreesC. Dc magnetic susceptibility studies at an applied field of 1000 G reveal that on cooling from room temperature, the material undergoes two structural phase transitions designated alpha {\textendash}> beta, and beta {\textendash}> gamma at 151 and 133 K, respectively. On warming, the gamma {\textendash}> beta and beta {\textendash}> alpha transitions are observed at 137 and 151 K, respectively; a 4 K thermal hysteresis clearly detectable in the lower temperature beta <{\textendash}{\textendash}> gamma transition. These structural phase transitions have also been studied by detailed, variable-temperature, ac susceptibility and Mossbauer spectroscopy techniques. Single-crystal X-ray diffraction studies done at 294, 143, and 113 K reveal 2, 12, and 6 unique iron centers in the alpha-, beta-, and gamma-forms, respectively. All three forms have the same basic structure involving 2D extended double layer sheets (bilayers) of alternating tetrahedral and octahedral irons singly bridged by imidazolate ligands, with the octahedral centers additionally coordinated by 2,2{\textquoteright}-bipyridine ligands that occupy positions between the sheets. Magnetic susceptibility and bond length data reveal that in the gamma-phase one in three six-coordinate sites corresponds to spin singlet ground-state iron(II); i.e., the overall alpha {\textendash}> gamma process involves a spin-crossover transition such that at least 1/6 of the iron sites in the gamma-phase correspond to S = 0. This is supported by the low-temperature Mossbauer spectra of the gamma-phase, which reveal the simultaneous presence of both S = 2 and S = 0 iron(II) centers. The compound magnetically orders, with a resultant small remnant magnetization, at low temperatures. The magnetic phase transition, studied by a combination of dc and ac susceptibility and Mossbauer techniques, occurs at T-c similar to 6.5 K.},
	keywords = {CHEMISTRY, COMPLEXES, CROSSOVER, CRYSTAL-STRUCTURE, ELECTRONIC-STRUCTURE, IRON(II), PYRAZOLATE},
	isbn = {0020-1669},
	url = {<Go to ISI>://000220583500020},
	author = {Patrick, B. O. and Reiff, W. M. and Sanchez, V. and Storr, A. and Thompson, R. C.}
}
@article {960,
	title = {Poly[(2,2 {\textquoteright}-bipyridine)tetrakis(imidazolato)diiron(II)]: Structural and spin-state phase transitions and low-temperature magnetic ordering in a unique 2-dimensional material},
	journal = {Inorganic Chemistry},
	volume = {43},
	number = {7},
	year = {2004},
	note = {ISI Document Delivery No.: 808QLTimes Cited: 9Cited Reference Count: 31},
	month = {Apr},
	pages = {2330-2339},
	type = {Article},
	abstract = {Poly[(2,2{\textquoteright}-bipyridine)tetrakis(imidazolato)diiron(II)] was synthesized by the reaction of ferrocene with imidazole in an excess of 2,2{\textquoteright}- bipyridine in a Carius tube at 130degreesC. Dc magnetic susceptibility studies at an applied field of 1000 G reveal that on cooling from room temperature, the material undergoes two structural phase transitions designated alpha {\textendash}> beta, and beta {\textendash}> gamma at 151 and 133 K, respectively. On warming, the gamma {\textendash}> beta and beta {\textendash}> alpha transitions are observed at 137 and 151 K, respectively; a 4 K thermal hysteresis clearly detectable in the lower temperature beta <{\textendash}{\textendash}> gamma transition. These structural phase transitions have also been studied by detailed, variable-temperature, ac susceptibility and Mossbauer spectroscopy techniques. Single-crystal X-ray diffraction studies done at 294, 143, and 113 K reveal 2, 12, and 6 unique iron centers in the alpha-, beta-, and gamma-forms, respectively. All three forms have the same basic structure involving 2D extended double layer sheets (bilayers) of alternating tetrahedral and octahedral irons singly bridged by imidazolate ligands, with the octahedral centers additionally coordinated by 2,2{\textquoteright}-bipyridine ligands that occupy positions between the sheets. Magnetic susceptibility and bond length data reveal that in the gamma-phase one in three six-coordinate sites corresponds to spin singlet ground-state iron(II); i.e., the overall alpha {\textendash}> gamma process involves a spin-crossover transition such that at least 1/6 of the iron sites in the gamma-phase correspond to S = 0. This is supported by the low-temperature Mossbauer spectra of the gamma-phase, which reveal the simultaneous presence of both S = 2 and S = 0 iron(II) centers. The compound magnetically orders, with a resultant small remnant magnetization, at low temperatures. The magnetic phase transition, studied by a combination of dc and ac susceptibility and Mossbauer techniques, occurs at T-c similar to 6.5 K.},
	keywords = {CHEMISTRY, COMPLEXES, CROSSOVER, CRYSTAL-STRUCTURE, ELECTRONIC-STRUCTURE, IRON(II), PYRAZOLATE},
	isbn = {0020-1669},
	url = {<Go to ISI>://000220583500020},
	author = {Patrick, B. O. and Reiff, W. M. and Sanchez, V. and Storr, A. and Thompson, R. C.}
}
@article {4669,
	title = {A computational study of two-state conformational changes in 16-electron [CpW(NO)(L)] complexes (L = PH3, CO, CH2, HCCH, H2CCH2)},
	journal = {Chemistry-a European Journal},
	volume = {5},
	number = {5},
	year = {1999},
	note = {ISI Document Delivery No.: 194UQTimes Cited: 20Cited Reference Count: 52},
	month = {May},
	pages = {1598-1608},
	type = {Article},
	abstract = {Electronically and coordinatively unsaturated [Cp*W(NO)(L)] complexes have been postulated as intermediates in several related systems. Model [CpW(NO)(L)] compounds (L= PH3, CO, CH2, H2CCH2, HCCH) have been investigated theoretically by means of density functional theory computational techniques. The structural parameters calculated for saturated [CpW(NO)(PH,)(L)] complexes are in good agreement with the solid-state molecular structures determined crystallographically for the corresponding [Cp*W(NO)(PMe3)(L)] compounds. The 16-electron, singlet [CpW(NO)(L)] species have geometries comparable to those of the same fragment in the phosphine adducts and include a highly pyramidal conformation at W. The energy of the triplet spin state is calculated to be close to or even lower than that of the singlet state for these unsaturated compounds, and depends largely on the pi-bonding capabilities of L (Delta Es-t=Delta E-t-Delta E-s = - 3.3 kcalmol(-1) (PH3), + 2.8 (CO), + 2.4 (CH2), +6.3 (H2CCH2), -2.3 (HCCH)). The optimization of partially constrained structures in both spin states allows for a conformational analysis of the [CpW(NO)(L)] species. The inversion of the conformation of the pyramidal singlet [CpW(NO)(L)] complexes via the planar-at-W triplet species (two-state pathway) is calculated to be competitive with the equivalent process solely along the singlet spin hypersurface. Rotation of the W-CH, bond in the singlet carbene species is also found to proceed more readily via a two-state pathway. The preferred alkyne conformation, the unusually stable triplet states, and the strong W-to-L sc-donation observed in these systems may all be rationalized by the relatively high energies of the occupied orbitals of the formally WO compounds.},
	keywords = {ACTIVATION, CROSSOVER, density functional calculations, H BOND, LIGAND, ligand effects, MOLECULAR CALCULATIONS, ORGANOMETALLIC NITROSYL CHEMISTRY, OXIDATIVE ADDITION, pi interactions, PIANO-STOOL COMPLEXES, REACTIVITY, REDUCTIVE ELIMINATION, SPIN, SPIN-STATE, TUNGSTEN},
	isbn = {0947-6539},
	url = {<Go to ISI>://000080212600026},
	author = {Smith, K. M. and Poli, R. and Legzdins,Peter}
}
@article {4497,
	title = {Ion association and condensation in primitive models of electrolyte solutions},
	journal = {Journal of Chemical Physics},
	volume = {111},
	number = {19},
	year = {1999},
	note = {ISI Document Delivery No.: 251GQTimes Cited: 34Cited Reference Count: 32},
	month = {Nov},
	pages = {9000-9008},
	type = {Article},
	abstract = {{Monte Carlo simulations have been used to investigate condensation and ion association in primitive models of electrolyte solutions. We have examined models in which the ions have equal diameter, the cation charge is +Zq, and the anion charge is -q, with Z=1},
	keywords = {BINARY MIXTURE, CHARGED HARD-SPHERE, COEXISTENCE, CONSOLUTE POINT, CRITICAL EXPONENT, CROSSOVER, FLUIDS, FREE-ENERGY, MONTE-CARLO, PHASE-EQUILIBRIA},
	isbn = {0021-9606},
	url = {<Go to ISI>://000083437400030},
	author = {Camp, P. J. and Patey, G. N.}
}
@article {4498,
	title = {Ion association in model ionic fluids},
	journal = {Physical Review E},
	volume = {60},
	number = {1},
	year = {1999},
	note = {ISI Document Delivery No.: 218KCTimes Cited: 20Cited Reference Count: 22},
	month = {Jul},
	pages = {1063-1066},
	type = {Article},
	abstract = {Monte Carlo simulations are used to investigate the temperature and pressure (density) dependence of ion association in the restricted primitive model. It is shown that at temperatures below the critical temperature T-c the vapor consists almost exclusively of strongly bound ion pairs at or near contact. Significant ion-pair dissociation begins at temperatures very near T-c. This raises the possibility that compositional fluctuations between strongly bound and free lions influence the critical behavior. We note qualitative similarities between the present results and the Kosterlitz-Thouless transition in the two-dimensional Coulomb gas. [S1063-651X(99)03107-4].},
	keywords = {BEHAVIOR, CHARGED, COULOMB GAS, CRITICALITY, CROSSOVER, HARD-SPHERE, LIQUID-VAPOR COEXISTENCE, MONTE-CARLO, PHASE-TRANSITION, RESTRICTED PRIMITIVE MODEL, SIMULATION},
	isbn = {1063-651X},
	url = {<Go to ISI>://000081550900132},
	author = {Camp, P. J. and Patey, G. N.}
}
