1 H -Imidazole-4-carbo­nitrile

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/75107/1/S1600536805014509.pd

Assessing Guest Selectivity within Metallacrown Host Compartments

15-MC-5 complexes associate in the solid state to form chiral compartments capable of binding guests. Using small molecular yardsticks, we are able to assess the size restrictions of these structures. Dicarboxylate guests that are too short to span the Gd III ions are stabilized by solvates that hydrogen bond to the uncoordinated carboxylate, while guests that are too long destroy the weakly associated structure. We also demonstrate that all that is required for guest encapsulation is unsaturation of the chain connection carboxylates rather than necessitating the presence of aromaticity. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/56027/1/1347_ftp.pd

Form IV of carbamazepine

Carbamazepine has been found to crystallize as a new polymorph that is stable at room temperature. We report the crystal structure of this C -centered monoclinic form (space group C 2/ c , cell parameters: a  = 26.609, b  = 6.9269, c  = 13.957, Β = 109.702), which consists of hydrogen bonded dimers with an anti -disposition. This represents the third modification of carbamazepine that has been crystallographically characterized, and the fourth for which cell parameters have been determined. Thus, it is designated as form IV of carbamazepine. Differences between the packing of the various polymorphs are discussed. © 2002 Wiley-Liss, Inc. and the American Pharmaceutical Association J Pharm Sci 91:1186–1190, 2002Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/34507/1/10093_ftp.pd

Manganese carbonyl complexes of 2,5-dimethylbismolyl. The crystal and molecular structure of ([eta]1-2,5-dimethylbismolyl) manganese pentacarbonyl

([eta]-1-2,5-Dimethylbismolyl)manganese pentacarbonyl (8) has been obtained from the reaction of 1-phenyl-2,5-dimethylbismole with lithium followed by BrMn(CO)5. Heating 8 to its melting point causes the loss of CO to produce ([eta]5-2,5-dimethylbismolyl)manganese tricarbonyl. Compound 8 crystallizes in the monoclinic crystal system, space group P 21 (No. 4) with a = 6.838(2) A, b = 6.424(1) A, c = 15.787(4) A, [beta] = 95.68(2)[deg] V= 6901.(2) A3 and Z = 2. A full structure has been determined and is compared with those of analogous compounds.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/30847/1/0000509.pd

Modeling vanadium bromoperoxidase: Synthesis, structure and reactivity of vanadium-imidazole complexes.

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Metallacrowns: A new class of metal binding agents

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Evaluating hydrogen bond interactions in enzymes containing Mn(III)-histidine complexation using manganese-imidazole complexes

It is often difficult to control hydrogen bond interactions in small molecule compounds that model metalloenzyme active sites. The imidazole-containing ligands 4,5-dicarboxyimidazole (H 3 DCBI) and 4,5-dicarboxy- N -methylimidazole (H 2 MeDCBI) allow examination of the effects of internal hydrogen bonding between carboxylate and imidazole nitrogen atoms. A new series of mononuclear manganese imidazole complexes have been prepared using these ligands: Mn(III)(salpn)(H 2 DCBI)(DMF) ( 1 ), Mn(III)(salpn)(HMeDCBI) ( 2 ), Mn(III)(dtsalpn)(HMeDCBI) ( 3 ), [Mn(IV)(dtsalpn)(HMeDCBI)]PF 6 ( 4 ), Mn(III)(salpn)(H 2 DCBI) ( 5 ), Mn(III)(dtsalpn)(H 2 DCBI) ( 6 ), and Mn(IV)(dtsalpn)(H 2 DCBI)PF 6 ( 8 ). Complexes 1 , 2 , 3 , 5 , and 6 have been prepared by direct reaction of salpn [salpn=(salicylideneaminato)-1,3-diaminopropane)] or dtsalpn [dtsalpn=(3,5-di- t -butylsalicylideneaminato)-1,3-diaminopropane)] and H 3 DCBI and H 2 MeDCBI with Mn(III) acetate, while complexes 4 and 8 were made by bulk electrolysis of complex 3 or 6 in dichloromethane. Complexes 1 , 2 , and 6 were characterized by X-ray diffraction. The impact of hydrogen bonding interactions of the complexes has been demonstrated by X-ray diffraction, cyclic voltammetry, and EPR spectroscopy. In all complexes the central metal ion is present in a six-coordinate geometry. Magnetic susceptibility measurements confirm the spin and oxidation states of the complexes. The cyclic voltammograms of 3 and 6 in dichloromethane reveal single, reversible redox waves with E 1/2 =600 mV and 690 mV, respectively. The X-band EPR spectrum of 4 shows a broad signal around g =4.4, and the corresponding complex 8 possesses a broad signal at slightly lower field ( g =5.5) than 4 . These studies demonstrate that even small changes in the effective charge of the imidazole ligand can have a profound impact on the structure, spectroscopy, and magnetism of manganese(IV) complexes. We use these observations to present a model that may explain the origin of the g =4.1 signal in the S 2 state of photosystem II.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/42327/1/s00775-002-0414-7.pd

A Planar [15]Metallacrown-5 That Selectively Binds the Uranyl Cation Note from the editor: According to IUPAC recommendations hydroxamic acid is retained as the name of a class, but the compounds are preferably named as N -hydroxy amides. The systematic name of the triply deprotonated ion salicylhydroximate (used throughout this communication) is thus N ,2-dioxi-dobenzoyl amide.

No Abstract.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/38806/1/199628411_ftp.pd

The reaction of sulfur with dilithio compounds. The syntheses and structures of phenanthro [1, 10-cd]-1,2-dithiole and phenanthro[4,5-cde] [1,2]dithiin

The sequential reaction of selected polycyclic aromatic hydrocarbons with butyllithium/TMEDA/hexane and sulfur allows preparation of ring-fused dithiins, dithioles, and thiophenes. In this manner, phenanthrene has been converted to phenanthro[4,5-cde][1,2]dithiin and phenanthro[1,10cd]-1,2-dithiole. Yellow crystals of the dithiin form in C2/c (#15) space group with Z = 4, a = 13.537(3) Å, b = 8.933(2) Å, c = 9.601(4) Å, and Β = 116.19 (2)°; while orange crystals of the dithiole form in P2 1 2 1 2 1 (#19) space group with Z = 4, a = 4.1507(5) Å, b = 14.436(3) Å, and c = 16.972(3) Å. Full structures have been determined for both compounds.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/38566/1/520050206_ftp.pd

Compositional and geometrical isomers of 15-metallacrowns-5 complexes

Two mixed valent, hexanuclear manganese clusters of general composition Mn(acetate)2[Mn(III)(salicylhydroximate)]5(pyridine)6, Mn(II)(OAc)2(15-MCMn3+N-5) have been prepared in [approximate] 70% yield. Structural characterization of these complexes using X-ray crystallography provides the first examples of 15 membered ring metallacrowns. A 15 membered chelate ring is constructed of five [Mn(III)---N---O] linkages. The five manganese(III) ions are designated Mn(1)---Mn(5). The Mn(1), Mn(2) and Mn(3) atoms adopt propeller configurations with [Lambda],[Delta],[Lambda] absolute stereochemistry, respectively. The Mn(4) and Mn(5) atoms are restricted to planar configurations. Both complexes contain a seven coordinate manganese(II) [Mn(6)] encapsulated in the core of this 15 membered ring. The Mn(6) polyhedron is best described using an 8 coordinate reference frame in which one of the vertices of a trigonal faced dodecahedron is vacant. The Mn(6) coordination sphere contains five hydroximate oxygen donors, provided by the metallacrown ring, and two oxygen from acetates that bridge between ring manganese(III) and the encapsulated manganese(II). Two geometrical isomers are formed that differ in the bridging acetate modes. In 1, the bridging acetate forms a bifurcated bridged between Mn(2) and Mn(6) while complex 2 has a bifurcated acetate bridge between Mn(5) and Mn(6). A compositional isomer, Mn(II)(acetate)(HSal)(15-MCMn3+N-5), 4, which substitutes the carboxylate function of salicylate for one of the acetates has also been prepared. This isomer adopts the same bifurcation mode, using the salicylate carboxylate, as complex 2. Studies to define the solution integrity of the metallacrowns are presented in addition to the solid state structure.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/31623/1/0000556.pd