J. H. Zhang

Bio: J. H. Zhang is an academic researcher from Northeastern University. The author has contributed to research in topics: Magnetic susceptibility & Antiferromagnetism. The author has an hindex of 12, co-authored 24 publications receiving 1385 citations.

Ferromagnetic behavior of [Fe(C5Me5)2]+.bul. [TCNE]-.bul.. Structural and magnetic characterization of decamethylferrocenium tetracyanoethenide, [Fe(C5Me5)2]+.bul. [TCNE]-.bul..cntdot.MeCN and decamethylferrocenium pentacyanopropenide, [Fe(C5Me5)2]+.bul. [C3(CN)5]-

Abstract: Les deux composes cristallisent dans le systeme monoclinique, groupe C2/C. Comportement magnetique

Ferromagnetic properties of one-dimensional decamethylferrocenium tetracyanoethylenide (1 : 1): [Fe(η5-C5Me5)2]˙+[TCNE]˙–

Abstract: [Fe(C5Me5)2]˙+[TCNE]˙– has been characterized by magnetic susceptibility to possess dominant ferromagnetic interactions; its structure has been determined by X-ray crystallography.

(. mu. -1,1 prime -Bis(diphenylphosphine)ferrocene)bis(chlorogold): Synthesis, iron-57 and gold-197 Moessbauer spectroscopy, x-ray crystal structure, and antitumor activity

Abstract: The title compound 2, Fdpp(AuCl){sub 2}, synthesized via the addition of Fdpp (1) to an aqueous solution of ((HOCH{sub 2}CH{sub 2}){sub 2}S)AuCl generated in situ by the thiodiglycol reduction of HAuCl{sub 4} showed a {sup 31}P({sup 1}H) NMR chemical shift at {delta} 27.39, which was downfield from that of 1 at {delta} -17.34 relative to (CH{sub 3}O)PO. The {sup 57}Fe Moessbauer spectrum of 2 is a doublet with parameters (IS = 0.50 mm/s relative to Fe, QS = 2.33 mm/s) similar to those of ferrocene. The {sup 197}Au Moessbauer spectrum of 2 is an asymmetric doublet (QS = 6.93 mm/s) with an IS of 3.81 mm/s relative to Au metal. Fdpp(AuCl){sub 2} crystallized in space group P{bar 1} with lattice constants a = 16.192 (4) {angstrom}, b = 16.921 (4) {angstrom}, and c = 10.878 (5) {angstrom} with Z = 3. Two crystallographically independent molecules, A and B, were observed in the structure of 2 with a chloroform solvate molecule per 1.5 formula units of the gold complex. For A, the P atoms are 180{degree} opposed and the rings exactly staggered, while in B the P atoms are 150{degree} apart and the rings are partially staggered. The P-Au-Cl linkage ismore » nearly linear, and the bond distances fall within normal ranges. Evaluation in an ip P388 leukemia mouse model showed 1 and 2 to have only marginal activity with an increased life span (ILS) relative to untreated controls of 30% at a maximally tolerated dose (MTD) of 231 {mu}mol/kg and 40% ILS at 4 {mu}mol/kg, respectively. 27 refs., 4 figs., 3 tabs.« less

Characterization of the charge-transfer reaction between decamethylferrocene and 7,7,8,8-tetracyano-p-quinodimethane (1:1): the 57Fe Mössbauer spectra and structures of the paramagnetic dimeric and the metamagnetic one-dimensional salts and the molecular and electronic structures of [TCNQ]n (n=0, −1, −2)

Abstract: The charge-transfer reaction of decamethylferrocene, Fe(C/sub 5/Me/sub 5/)/sub 2/, Fc*, and 7,7,8,8-tetracyano-p-quinodimethane, TCNQ, has been characterized. Three major reaction products of varying stoichiometry, conductivity, and magnetism are formed: a 1-D metamagnetic 1:1 salt, (Fc*)/sup +/(TCNQ)/sup -/; a paramagnetic (Fc*)/sup 2/ /sup +/(TCNQ)/sup 22 -/; 1:1; dimeric salt, (Fc*)/sup 2/ /sup +/(TCNQ)/sup 22 -/; and a conducting 1:2 salt of (Fc*) /sup +/(TCNQ)/sup 2 -/ composition. The crystal and molecular structures of the 1:1 paramagnetic dimeric and metamagnetic one-dimensional salts were solved. The ions in the dimeric phase crystallize in the centrosymmetric monoclinic space group P2/sub 1//c with a = 9.708 (1) A, b = 12.211 (2) A, c = 23.585 (4) A, ..beta.. = 95.01 (1)/sup 0/, Z = 4, and R = 0.058 for 3665 independent reflections. The magnetic susceptibility of powder samples of (Fc*)/sup 2/ /sup +/(TCNQ/sub 2/)/sub 2//sup 2 -/ obeys the Curie expression above 1.5 K suggesting very little magnetic coupling between the intradimer S = 1/2 Fe(III)'s which are separated by approx.14 A. The (TCNQ)/sub 2//sup 2 -/ dimer is strongly antiferromagnetically coupled. Ions in the linear chain metamagnetic phase crystallize in the centrosymmetric triclinic space group P1 vector. The unit cell at -106 /supmore » 0/C is a = 8.635 (4) A, b = 9.384 (6) A, c = 10.635 (9) A; ..cap alpha.. = 116.76 (5)/sup 0/, ..beta.. = 112.58 (5)/sup 0/; ..gamma.. = 72.49 (4)/sup 0/, V = 701.8 A/sup 3/, Z = 1, and R/sub w/ = 0.060 for 1156 reflections. The one-dimensional phase exhibits metamagnetic properties with a Neel temperature of 2.55 K. The intrachain Fe/sup III/-Fe/sup III/separation is 10.540 A. The calculated structure and scaled vibrational frequencies are in excellent agreement with the observed values.« less

Chemical Redox Agents for Organometallic Chemistry

Abstract: 1. Advantages of Chemical Redox Agents 878 2. Disadvantages of Chemical Redox Agents 879 C. Potentials in Nonaqueous Solvents 879 D. Reversible vs Irreversible ET Reagents 879 E. Categorization of Reagent Strength 881 II. Oxidants 881 A. Inorganic 881 1. Metal and Metal Complex Oxidants 881 2. Main Group Oxidants 887 B. Organic 891 1. Radical Cations 891 2. Carbocations 893 3. Cyanocarbons and Related Electron-Rich Compounds 894

Polyoxometalate-Based Molecular Materials

Abstract: Molecule-based materials with active physical properties, in particular electrical, magnetic, and optical, are a focus of contemporary materials chemistry research. Certainly, one reason for this interest has been the realization that these materials can exhibit cooperative properties typically associated with the inorganic network solids, as for example metallic conduction or even superconductivity,1 ferromagnetism,2 and nonlinear optical properties.3 With respect to the electrical properties, many important achievements were obtained in the 1970s with the discovery of the first molecule-based metal in 1972,4 namely the π-electron donor-acceptor complex [TTF][TCNQ] (TTF ) tetrathiafulvalene, TCNQ ) tetracyano-p-quinodimethane),5 and the report of the first molecule-based superconductors in 1979 based on the Bechgaard salts [TMTSF]2X (X ) PF6, AsF6; TMTSF ) tetramethyltetraselenafulvalene).6 The recognition of molecule-based ferromagnetic compounds is more recent and has emerged only in the past decade with the discovery of the electron-transfer salt [Fe(C5Me5)2][TCNE] (TCNE ) tetracyanoethylene) in 1985.7 Since these pioneering studies, the two areassmolecule-based metals and magnetsshave witnessed rapid development, and many new molecules have been designed which, if assembled in the appropriate manner in the solid, will enable researchers to improve the physical properties by increasing superconducting and ferromagnetic critical temperatures. A current development in the general area of molecule-based materials is to design, from a wise choice of the constituent molecules, new materials that combine properties not normally associated with a single material. Some intriguing applications of this concept would be to couple conductivity or optical phenomena with magnetic properties. In fact, this challenging goal was proposed8 in the mid-1980s but has only recently begun to be explored. Efforts in this direction nucleated with the design of hybrid materials formed by two molecular networks, such as anion/cation salts or host/guest solids, where each network furnishes distinct physical properties. In these new types of materials, each network contributes distinct physical properties to the solid. Examples include hybrid molecule-based materials, combining inorganic metal complexes that act as structural or magnetic components with an organic π-electron donor or acceptor molecule that furnishes the pathway for electronic conductivity.9 Polyoxometalates have been found to be extremely versatile inorganic building blocks for the construction of the aforementioned functionally active solids.10 The present article highlights recent results and provides a perspective of the use of polyoxometalates in the construction of molecule-based materials. We present herein the different classes of polyoxometalate-based hybrid materials that are of considerable interest due to their electrical or/and magnetic properties. These are (i) organic/inorganic hybrid salts in which the electron donors are organic molecules of the TTF type, (ii) organometallic/inorganic salts in which the electron donor is the decamethylferrocene complex, and (iii) organic/inorganic films in 273 Chem. Rev. 1998, 98, 273−296

Toward molecular magnets: The metal-radical approach

Abstract: Molecular materials are characterized by being made up by discrete molecules. This structural property gives in principle many possibilities, to modulate the bulk electrical, magnetic, and optical properties of the material by choosing appropriately the constituent molecules. At the same time, however, it is a challenge to develop synthetic strategies that allow the control of the spatial distribution of the molecules in the lattice. In fact, the bulk properties are always determined by cooperative interactions between the constituent molecules, which consequently must be assembled in the lattice in such a way as to maximize the bulk response. In this Account we provide a concise resume of magnetic phenomena, report briefly on the different strategies that have been developed up to the moment for designing molecular magnetic materials, and then summarize our own approach and the main results that have been obtained in this area.