@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 {7369,
	title = {SYNTHESIS AND CHARACTERIZATION OF DERIVATIZED CAPPED PORPHYRINS},
	journal = {Canadian Journal of Chemistry-Revue Canadienne De Chimie},
	volume = {70},
	number = {5},
	year = {1992},
	note = {ISI Document Delivery No.: JL870Times Cited: 4Cited Reference Count: 31},
	month = {May},
	pages = {1366-1374},
	type = {Article},
	abstract = {{The syntheses of porphyrins carrying either a fully hydrophobic cavity with a benzene moiety (32a,b) or a polar cavity with an amidobenzene (32c-d) are described. Terephthaldehyde (1) was converted to benzene-bisalkanoic acids (8, 10) and nitrobenzene-bisalkanoic acids (13 and 16) by using standard methods. The corresponding diacid chlorides 17a-d were used to acylate two equivalents of a beta-unsubstituted pyrrole, and the ketonic groups were reduced by diborane. Following the transformation of the nitro function to the acetamide, appropriate modifications of the ethyl ester functions afforded the key bisformylpyrroles 25a-d. The cyanoacrylate-protected formyl pyrrole derivatives were mono-chlorinated at the alpha-methyl groups and condensed with two equivalents of an alpha-unsubstitutued pyrrole to give the dipyrromethane dimers. Strong aqueous alkali caused saponification of the two ester groups and deprotection of the formyl functions to produce the dipyrromethane dimer 30, which, after thermal decarboxylation, was cyclized intramolecularly in acidic medium to give the porphyrins 32 (n = 4 or 5},
	keywords = {BINDING, CO, HUMAN OXYHEMOGLOBIN, IRON(II), O-2, RESOLUTION, STEREOCHEMISTRY},
	isbn = {0008-4042},
	url = {<Go to ISI>://A1992JL87000017},
	author = {Tang, H. and Wijesekera, T. P. and Dolphin, D.}
}
