Download or read book Synthesis and Magnetic Properties of Some Mononuclear Binuclear and Mixed metal Binuclear Transition Metal II Complexes written by Raymond L. Hough and published by . This book was released on 1973 with total page 150 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Synthesis Molecular Structure and Magnetic Properties of Some Binuclear Transition Metal Complexes with Exogenous Bridging Ligands written by Estelle Quijano and published by . This book was released on 1990 with total page 160 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Synthesis and Magnetic Properties of Some Binuclear Divalent Transition Metal Di and Triketonates written by Londa L. Borer and published by . This book was released on 1972 with total page 266 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Mononuclear and Binuclear Transition Metal Complexes Containing the Ligand 2 Diphenyl phosphino pyridine written by James Paul Farr and published by . This book was released on 1982 with total page 520 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Structures and Properties of Some Mononuclear and Binuclear Transition Metal Schiff Base Complexes written by Derek Peter Freyberg and published by . This book was released on 1977 with total page 336 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Synthesis and Photophysical Properties of Binuclear Transition Metal Compounds written by Charles Allen Daws and published by . This book was released on 1993 with total page 436 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Magnetism and Coordination Chemistry of Mononuclear and Polynuclear Complexes of Copper II and Other First Row Transition Metal Ions Derived from Open chain Diazine N N Ligands written by Zhiqiang Xu and published by . This book was released on 1998 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis describes the structures and the magnetic properties of the first row transition metal complexes containing open-chain diazine (N-N) moieties. The purpose of the research is to establish a magnetostructural correlation involving the N-N single bond bridge and to investigate the coordination chemistry of open-chain diazine ligands to the first row transition metal ions. A relevant literature search is presented in Chapter 1. -- Chapter 1 describes a general introduction to magnetic exchange in polynuclear copper complexes and a general review of the coordination chemistry of diazine (N2) bridged complexes. In Chapter 2, seventeen dicopper(II) complexes with five open-chain diazine ligands (PAHAP, PMHAP, PHMAP, PHAAP and PYPZ) are reported, in which the two copper(II) centers are bridged by a single N-N bond only. The X-ray structures of one ligand and twelve dinuclear copper(II) complexes were determined. Changing the ligands, together with varying the coligands leads to a situation where the dihedral angle between the copper planes can be varied from 75° to 168.5°. For small angles (less than 80°) ferromagnetic coupling prevails, whereas at larger angles antiferromagnetic exchange is observed between the copper(II) centers. The exchange integrals (-2J) vary from -24.4 to 210 cm−1. This is associated with the degree of alignment of the nitrogen p orbitals in the diazine bridge, and is supported by molecular orbital calculations on the complexes and appropriate models. Chapter 3 deals mainly with dinuclear copper(II) complexes containing two ligands bridging two metal centers. The dinuclear copper(II) complexes containing two N-N single bonds have no or very weak coupling because of orbital orthogonality and the twisting of the two copper planes around these two N-N single bonds. A dicopper complex containing mixed diazine bridges (pyridazine/N-N) shows weak antiferromagnetic coupling, and since the diazine unit in the aromatic ring system bridges two copper centers in an orthogonal manner, this net antiferromagnetic coupling occurs only through the open-chain diazine bridge. A tetranuclear copper complex contains two pairs of dicopper(II) centers bridged orthogonally by two μ2-1,1-azide anions with each pair of copper(II) centers bridged by one N-N single bond and one μ2-1,1-azide with a 119° azide bridge angle. The dihedral angle about the N-N single bond is 54°, which indicates either no coupling or weak ferromagnetic coupling via such a bridge. Therefore, the strong antiferromagnetic coupling (-2J = 246 cm−1 ) occurs only through the μ2-1,1-azide bridges between each pair of copper(II) centers, giving the first genuine example contradicting the spin polarization mechanism associated with azide bridges. In Chapter 4, a series of spiral-like dinuclear complexes of Mn(II), Fe(II), Fe(III), Co(II), Co(III) and Ni(II) ions containing three N-N single bonds with a formula [L3M2].(X)n.mH2O (L = PAHAP, PZHPZ; X = CIO4 or NO3; n = 4, 6) and a seven-coordinate Fe(III) complex are discussed. The X-ray structures of six of these complexes have been determined. Variable-temperature magnetic properties, electrochemistry and spectra are discussed. Chapter 5 discusses the synthesis, structural and magnetic properties of some mononuclear and polynuclear first row transition metal complexes of the open-chain diazine ligands. The X-ray structures of eight complexes were determined. Two new coordination modes for open-chain diazine ligands have been found. In the last chapter, a general conclusion about coordination modes, magnetostructural correlations, etc. of the open-chain diazine complexes is made.
Download or read book American Doctoral Dissertations written by and published by . This book was released on 1993 with total page 704 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Synthesis Magnetic and Spectral Studies of Some Mono and Binuclear Transition Metal Complexes of Substituted 1 3 5 triketones and Their Schiff base Derivatives written by James Lonzo Mack and published by . This book was released on 1978 with total page 220 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Synthesis and Characterization of Low Coordinate Transition Metal Complexes written by Aimee M. Bryan and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation describes the synthesis, characterization, and reactivity studies of new low-coordinate complexes of readily available and inexpensive transition metals such as iron, cobalt and nickel. The compounds were magnetically characterized in detail and tested for single molecule magnet (SMM) behavior. SMMs are a topic of intense research because of their potential applications in magnetic memory, high-density information storage and quantum computing technologies. Low-coordinate compounds display magnetic moments that indicate high orbital angular momentum and are very promising candidates for SMM behavior because they also tend to have large negative zero-field splitting (D) values. The complexes reported here are stabilized by using a variety of amido, aryloxo and thiolato ligands with bulky terphenyl groups and also using aryl and alkyl substituted silylamides. A superconducting quantum interference device (SQUID) and Evans' methods were used to study the magnetic properties and single crystal X-ray crystallography and NMR (1H and 13C) were used to confirm the structures of these compounds in both the solid and solution states. Further characterization studies included UV-visible, near-IR, and IR spectroscopy, melting point, elemental analysis and DFT calculations, where applicable, in order to determine the electronic configurations and bonding schemes. At present there are ca. 100 stable open shell two-coordinate mononuclear transition metal complexes currently known but ca. 20% have a linear coordination at the metal atom with only a few being strictly 180° at their metal center. Very few of these compounds had been magnetically characterized. In Chapter 2, the synthesis and magnetic characterization of the late transition metal Co2+ (d7) and Ni2+ (d8) primary amido complexes Co{N(H)Ar(iPr6)}2, Co{N(H)Ar(Me6)}2, Ni{N(H)Ar(iPr6)}2 and Ni{N(H)Ar(Me6)}2 (Ar(Me6) = C6H3-2,6(C6H2-2,4,6-Me3)2, Ar(iPr6) = C6H3-2,6(C6H2-2,4,6-(i)Pr3)2) are described. The investigations showed that they exhibit interesting magnetic behavior. The bent versus linear geometries of the complexes enable direct observation of the effects of orbital angular momentum quenching upon bending the metal coordination geometry. The electronic configuration of the linear cobalt(II) complexes does not predict first order orbital angular momentum and yet, the magnetic moment of Co{N(H)Ar(iPr6))2 is much higher than the spin only value which suggests a large spin-orbit coupling effects due to mixing of the ground and excited states. In Chapter 3, the synthesis and characterization of the mononuclear chromium, iron, cobalt and nickel terphenyl substituted thiolate complexes Cr(SAr(Me6))2, Cr(SAr(iPr4))2, Fe(SAr(iPr4))2, Co(SAr(iPr4))2 and Ni(SAr(iPr4))2 are described. Their structures show bent coordination geometries of varying degree with strong secondary M-[eta]6 and M-C(ipso) flanking aryl ring interactions of ca. 2.153 [Angstrom] for Fe(SAr(iPr4))2, ca. 1.625 [Angstrom] for Co(SAr(iPr4))2 and ca. 1.731 [Angstrom] for Ni(SAr(iPr4))2. This observation is in sharp contrast to the almost linear coordination observed for the derivatives of the related but more crowded terphenyl thiolate ligand, SAr(iPr6), in M(SAr(iPr6))2 complexes where M = Cr, Fe, Co and Ni and the strictly linear geometry observed for the terphenyloxo analogs M(OAr(iPr4))2 where M = Fe and Co. Magnetic moments for these species are, in general, lower than the spin-only values. Expect for chromium, this is an unexpected observation for late transition metal low-coordinate complexes. The suppression of magnetic moments is most like due to the strong M-arene interactions which effectively increases the coordination number at the metal atom. These results demonstrate the important role that substituents play on the flanking rings of the terphenyl ligands and begs further investigations involving the role of dispersion in the isolation of low coordination mononuclear transition metal complexes. The divalent silylamides M{N(SiMe3)2}2 (M = Mn, Fe, and Co) are key synthons for low-coordinate transition-metal derivatives. In Chapter 4, the previously reported, but incorrectly characterized cobalt(II) silylamide, [Co{N(SiMe3)2}2]2 has been spectroscopically and magnetically characterized for the first time. In addition, the new Lewis base complexes [Co{N(SiMe3)2}2(PMe3)], and [Co{N(SiMe3)2}2(THF)], as well as a previously reported complex [Co{N(SiMe3)2}2(py)] were isolated and characterized. Magnetic studies showed that they had considerably larger magnetic moments than the spin-only value of 3.87 [mu](B), which is indicative of a significant zero-field splitting and g-tensor anisotropy. In addition to their interesting magnetic behavior and unexpectedly large D values in the range of -20 to -80 cm−1. The electronic spectrum of [Co{N(SiMe3)2}2]2 in solution showed that earlier characterization spectra of "Co{N(SiMe3)2}2" match that of the bright green THF adduct and not the dark brown cobalt dimer [Co{N(SiMe3)2}2]2. In Chapter 5, it is shown that the reaction of the versatile cobalt(II) amide, [Co{N(SiMe3)2}2]2, with four equivalents of the sterically crowded terphenyl phenols, HOAr(Me6) and HOAr(iPr4) (Ar(iPr4) = C6H3-2,6(C6H3-2,6-(i)Pr2)2) produced the first well-characterized, monomeric two-coordinate cobalt(II) bisaryloxides, Co{OAr(Me6))2 and Co(OAr(iPr4))2. Not only are these very rare examples of two-coordinate transition metal(II) aryloxides, but the magnetic moments of both the linear and the bent species were well in excess of the spin only value for cobalt(II) ion. It was demonstrated that careful manipulation of the synthetic conditions for Co(OAr(iPr4))2 could produce varying occupancies of the cobalt(II) site and that after weighting the magnetic susceptibilities of the compounds accordingly, the moments were shown to be in close agreement with each other. Chapter 6 reports the synthesis of the unstable nickel(II) bis(silylamide) complex Ni{N(SiMe3)2}2 via the reaction of NiI2 and two equivalents of NaN(SiMe3)2 in tetrahydrofuran, as well as two of its Lewis base adducts, Ni{N(SiMe3)2}2(THF) and Ni{N(SiMe3)2}2(py)2. The reaction of two equivalents of LiN(SiMe3)2 with NiCl2(DME) in tetrahydrofuran afforded the reduced homoleptic tetrameric nickel(I) amide complex, [Ni{N(SiMe3)2}]4. This unique polymetallic structure having a Ni4N4 planar array has four S = 1/2 nickel (I) ions and an antiferromagnetic exchange coupling constant of J = -102(2) cm−1. This study provides strong evidence that the formation of nickel(II) and nickel(I) amido complexes is possible without the use of sterically demanding ligand sets.
Download or read book Synthesis and Chemistry of Flexibly Coupled Binuclear Transition Metal Complexes with Macrocyclic Ligands written by Mohamed A. Khalifa and published by . This book was released on 1981 with total page 350 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Magnetic Exchange Interactions and Mixed Valence Chemistry in Binuclear Transition Metal Complexes written by and published by . This book was released on 1981 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Studies of Transition Metal Complexes Using a New Unsymmetric Multidentate Chelate Ligand written by Satcher, Jr. (Joe Harold) and published by . This book was released on 1995 with total page 622 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Synthesis Characterization and Magnetic Properties of Some Transition Metal Diorganophosphinate and Dimethylarsinate Complexes written by Shihua Xia and published by . This book was released on 1997 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Synthesis Structures and Characterization of Coordination Compounds with the Transition Metals Ni II Cu II Mn II Cr III Fe III Using Ligands Based on Iminodiacetic Acid and N heterocycles written by Maria Paula Juanico and published by Cuvillier Verlag. This book was released on 2003 with total page 151 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Synthesis and Magnetic Properties of Transition Metal II 1 3 5 triketonate Complexes written by Daniel Patrick Murtha and published by . This book was released on 1970 with total page 198 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Synthesis and Characterization of Binuclear and Transition Metal Complexes Incorporating the Tridentate Chelating Ligand Dimethyl N N dimethylethanolamino 1 pyrazolyl gallate written by and published by . This book was released on 1977 with total page 66 pages. Available in PDF, EPUB and Kindle. Book excerpt:
