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Book Synthesis Structure and Reactivity of Polynuclear Transition Metal Complexes

Download or read book Synthesis Structure and Reactivity of Polynuclear Transition Metal Complexes written by Oi Mi Lacy and published by . This book was released on 1985 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book The Synthesis and Reactivity of Di and Polynuclear Mixed Metal Complexes

Download or read book The Synthesis and Reactivity of Di and Polynuclear Mixed Metal Complexes written by C. Marsden and published by . This book was released on 1985 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Synthesis and Characterization of Novel Polynuclear Group 6 Carbonyl Anionic Complexes Obtained by Ligand Exchange Reactions

Download or read book Synthesis and Characterization of Novel Polynuclear Group 6 Carbonyl Anionic Complexes Obtained by Ligand Exchange Reactions written by Rafael A. Adrian and published by . This book was released on 2004 with total page 304 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Metal Pyrrolide Complexes in Three fold Symmetry

Download or read book Metal Pyrrolide Complexes in Three fold Symmetry written by William Hill Harman and published by . This book was released on 2010 with total page 414 pages. Available in PDF, EPUB and Kindle. Book excerpt: Given the prominence of six-coordinate pseudo-octahedral complexes in transition metal chemistry, lower coordinate complexes in tetrahedral, trigonal pyramidal and trigonal bipyramidal configurations have garnered increased interest due to the changes in electronic structure and reactivity resultant from three-fold symmetry relative to the four-fold symmetry commonly observed in their pseudo-octahedral counterparts. Herein, we report a range of such effects in a collection of transition metal complexes supported by chelating, trianionic trispyrrolide ligands [tpaR]3-. In chapter one, two trigonal pyramidal iron(II) complexes, [(tpaPh)Fe]- and [(tpaMes)Fe]-, are discussed which are capable of undergoing oxygen atom transfer reactions and subsequent activation of strong C-H bonds. Additionally, the mesityl derivative is capable of oxygen atom transfer from nitrous oxide, an attractive but notoriously unreactive molecule. In chapter two, this family of iron(II) complexes is expanded to include tert-butyl, 2,4,6-triisopropylphenyl and 2,6-difluorophenyl substituted variants, and the magnetic properties of this homologous series of trigonal pyramidal iron(II) complexes are explored. Notably, a number of these complexes exhibit frequency dependent signals at low temperature in the imaginary component of ac magnetic susceptibility measurements performed in the presence of a small applied field. Further exploration of this behavior via magnetometry, high-field EPR and Mössbauer spectroscopy reveal a large barrier to magnetic relaxation in these complexes, in some cases comparable to the best known single molecule magnets. This phenomenon is accounted for by the unquenched orbital angular momentum present in a three-fold symmetric high spin d6 system, leading to significant uniaxial anisotropy and a barrier to spin inversion. Progress towards a magneto-structural analysis of this behavior is made for this series. Chapter three contains a through treatment of the coordination, redox and group transfer chemistry of the iron(II) platform [(tpaMes)Fe]-. In particular, it is shown that this complex is capable of supporting both high and low spin five coordinate adducts, including a rare example of a paramagnetic carbonyl complex of iron(II), [(tpaMes)Fe(CO)]-. Furthermore, the redox chemistry of this system is illustrated in the synthesis of the neutral iron(III) complex (tpaMes)Fe(i-PrNH2). As an extensiont to the oxygen atom chemistry presented in chapter one, nitrene group transfer to [(tpaMes)Fe]- is described, resulting in the synthesis of an iron(III) amido complex. The identity of this species is confirmed by high resolution electrospray mass spectrometry as well as Mössbauer, x-ray absorption and EPR spectroscopies. In chapter four, the vanadium chemistry of [tpaR]3- is introduced. In particular, the vanadium(III) complex (tpaMes)V(THF) is show to react with an aryl azide to yield an isolable vanadium(V) diazenylimido species, a member of a very rare structural type. This complex is shown to decompose unimolecularly by dinitrogen loss to generate the cooresponding vanadium(V) imido. In addition to the vanadium-nitrogen multiple bond chemistry described, the synthesis two pseudo-three-fold symmetric vanadium(IV) oxo species is discussed. Single crystal x-ray structures of both complexes reveal a distorted coordination geometry and a short vanadium-oxo distance, consistent with a triple bond. The oxidation of both of these complexes to the corresponding vanadium(V) oxo is performed and shown by x-ray crystallography to result in the relief of the distortion observed in the vanadium(IV) oxo complexes. Taken together, these results shed light on the nature of metal ligand multiple bonding in three-fold symmetric geometries. Chapter five discusses the chromium complexes of [tpaMes]3-, in particular the group transfer and redox chemistry of the system. Both chromium(II) and chromium(III) complexes are available by direct metallation, and the chromium(II) complex [(tpaMes)Cr(DME)]- is shown to undergo both oxygen atom and nitrene group transfer reactions to yield chromium(IV) oxo and imido complexes respectively. The chromium(IV) imido complex exhibits rich redox chemistry, and its oxidation to the isostructural chromium(V) and chromium(VI) complexes are demonstrated.

Book Polynuclear Group 13 Compounds Synthesis Characterization and Reactivity

Download or read book Polynuclear Group 13 Compounds Synthesis Characterization and Reactivity written by Marcella E. Desat and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Structural and Reactivity Studies on Binuclear Metal Complexes

Download or read book Structural and Reactivity Studies on Binuclear Metal Complexes written by Raymond Stanley Dickson and published by . This book was released on 1984 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis describes the synthesis and characterization of some diphosphine-bridged, binuclear rhodium complexes which contain bridging acetylene ligands, and some chemistry of these complexes with selected small molecules. The X-ray crystal structure of an unusual ironpalladium-bonded heterobinuclear complex is also reported. The complexes [Rh2x2([Mu]-RCCR)(DPM)2] (I: X = Cl, R = CF3; 2: X = I, R = CF3; 3: X = Cl, R = C02CH3; DPM = bis(diphenylphosphino)methane) were synthesized by the reaction of [RhCl(C8H12)]2 and two equivalents of DPM with the appropriate activated acetylene, CF3C2CF3(hexa-fluoro2-butyne, HFB) or CH3O(O)CC2C(O)OCH3(dimethylacetylenedicarboxylate, DMA), followed by halide metathesis of 1 with KI to obtain 2. The crystal structure of [Rh2Cl2([Mu]-HFB)(DPM)2] (1) was determined to establish the mode of acetylene binding in this complex (space group P43, a = 21.283(1) A, c = 14.255(1) A, z = 4; 5243 unique reflections; R = 0.040, Rw = 0.055). The complex was shown to be a distorted "A-frame" complex, having a metal-metal bond (Rh(1)-Rh(2) = 2.7447(9) A), two terminal chloride ligands and a bridging acetylene moiety coordinated parallel to the metal-metal axis, as a so-called cisdimetallated olefin. Most parameters of this group suggested sp2 hybridization of the central two carbon atoms. The reactions of compouns 1, 2 and 3 with CO and SO2 were reversible and gave products in which these small molecules had inserted into the Rh-Rh bonds. Protonation by the strong acids CF3SO3H and HBF4•(C2H5)2o also occurred reversibly at the metal-metal bonds and was most probably accompanied by anion coordination at one metal centre. However, methyl isocyanide (CNMe) reacted quite differently, yielding complexes in which the isocyanide ligands are bound terminally. Although all of compounds 1 - 3 reacted with CNMe in a rather analogous manner there were some subtle differences observed. Stepwise addition of CNMe to compound 1 yielded two unsymmetrical, isomeric 1:1 adducts, [Rh2Cl2 (CNMe) (Mu-HFB ) (DPM)2], followed by a 2:1 adduct, [Rh2Cl(CNMe)2(Mu-HFB)(DPM)2] [Cl] , and finally by a 4:1 adduct [Rh(CNMe)4(Mu-HFB)(DPM)2][Cl]2. The iodo analogue species 2 gave analogous products except that the isomer ratio of the 1:1 adduct differed and a second symmetric 2:1 adduct, [Rh2I2(CNMe)2(Mu-HFB)(DPM)2], was also observed. With the DMA-bridged species 3 only one 1:1 adduct was observed and all other products were analogous to the reactions of compound 1. The unsymmetrical 2:1 adduct of compound 1 was isolated as the BF4- salt, [Rh2Cl(CNMe)2(Mu-HFB)-(DPM)2][BF4]. Its X-ray crystal structure determination (space group P21/n, a = 16.366(3) A, b = 18.685(3) A, c = 20.425(4) A, [Beta] = 104.35(1)°, Z = 4; 6800 unique observations; R = 0.059, Rw = 0.097) showed that the metalmetal bonded complex retained the cis-dimetallated olefinic binding mode of the acetylene group; one metal had a terminal chloro ligand whereas the other had two terminal CNMe groups. [(PPh3)PdFe(SC5H4)2] was prepared and crystallized as the hemitoluene solvate by Mr. T.G. Rucker, Dr. B.W. Hames and Dr. Dietmar Seyferth at M.I.T., via the reaction of Pd(PPh3)4 with Fe(C5H4)2S3. The X-ray crystal structure (space group C2/c, a = 39.258(5) A, b = 10.548(2) A, c = 13.612(4) A, [Beta] = 101.69(2)°, Z = 8; 3255 unique observed reflections; R = 0.040, Rw = 0.046) showed that the compound had an unusual iron-palladium dative-bonded structure (Fe[right arrow]Pd = 2.878(1) A) with the palladium chelated at trans positions by the two cyclopentadienethiolato sulfurs. The triphenylphosphine ligand is attached to the palladium trans to the metal-metal bond. The tilt angle found between the two cyclopentadienthiolate rings was only 19.6°, about half of those observed for other Cp2MLn compounds.

Book Synthesis and Reactivity of Main Group Complexes for Applications in Small Molecule Activation

Download or read book Synthesis and Reactivity of Main Group Complexes for Applications in Small Molecule Activation written by Minh Tho Nguyen and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The work described in this thesis is focused on the preparation of a series of novel main group complexes, featuring unusual structural and bonding situations, and the study of their reactivity toward small molecules. The new zinc complexes dimphZnBu (V-2) and dimphZnCl2Li(THF)3 (V-3), supported by a diiminophenyl (dimph) ligand were prepared. The reaction of complex V-3 with LiHBEt3 resulted in hydride transfer to the C=N imine group to give an unusual zinc dimer (V-7). The latter transformation occurs via formation of compound (ɳ1(C),ĸ1(N)- 2,6-(2,6-iPr2C6H3N=CH)2C6H3)2Zn (V-5) which can be also accessed by reduction of V-7 with KC8. Diiminophenyl (dimph) proved to be an excellent ligand platform to stabilise a low-valent phosphorus centre. The resultant compound dimphP (VI-2), which can be rationalised as an imino-stabilised phosphinidene or benzoazaphopshole, shows remarkable chemical stability toward water and oxygen. VI-2 reacts with excess strong acid HCl to generate the P(III) chloride (dimHph)PCl (VI-6). Surprisingly, substitution of the chloride under some nucleophilic (KOBut) and electrophilic conditions (Me3SiOTf) regenerates the parent compound VI-2 by proton removal from the weakly acidic CH2N position. A related species (dimH2ph)P (VI-10) is produced upon thermal rearrangement of the hydride (dimHph)PH (VI-9). The molecular structure and reactivity of compounds VI-2 and other related compounds are also discussed. The reduction of the O,C,O-chelated phosphorus (III) chloride (VI-16) ( O,C,O = 2,6-bis[(2,6-diisopropyl)phenoxyl]phenyl) with KC8 or PMe3 resulted in the formation of a cyclic three-membered phosphorus compound (VI-18). The intermediacy of phosphinidene VI-17 was confirmed by trapping experiments and a VT 31P{1H} NMR study. The reaction of in-situ generated phosphinidene with either PhSiH3 or HBpin resulted in the formation of an unprecedented phosphine (VI-23). The treatment of VI-16 with two equivalents of DippNHC carbene led to ArP(Cl)NHC product (VI-24). The germylone dimNHCGe (dimNHC = diimino N-Heterocyclic Carbene, VII-8) was successfully prepared by the reduction of germanium cation (VII-7) with KC8. The molecular structure of VII-8 was unambiguously established, using NMR spectroscopy and single-crystal X-ray diffraction analysis. The reactivity of VII-8 was investigated. VII-8 is inactive towards butadiene but undergoes an oxidative cyclization with tetrachloro-o-benzoquinone to give a tetragermanium derivative. VII-8 undergoes oxidation addition of CH3I and PhI, followed by an unusual migration of the Me and Ph groups from germanium to the carbene ligand. Related chemistry takes place upon protonation with dry HCl, which results in the migration of the hydride to the carbene ligand.

Book American Doctoral Dissertations

Download or read book American Doctoral Dissertations written by and published by . This book was released on 1998 with total page 784 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Study of Di and Polynuclear Metal Complexes

Download or read book Study of Di and Polynuclear Metal Complexes written by Antonius Franciscus Maria Josephus van der Ploeg and published by . This book was released on 1981* with total page 180 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Synthesis Structural and Electronic Properties and Reactivity of Group 5 Metal Complexes Incorporating the Redox active ONO Ligand Platform

Download or read book Synthesis Structural and Electronic Properties and Reactivity of Group 5 Metal Complexes Incorporating the Redox active ONO Ligand Platform written by Steven Paul Hananouchi and published by . This book was released on 2014 with total page 67 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis describes the synthesis, electronic and structural properties, and reactivity of Group 5 metal complexes incorporating the [ONO] ligand platform. A study of the electronic and structural properties of the Group 5 metal complexes incorporating the [ONO] ligand is performed. Once the electronic properties of the complexes are known, the reactivity of the complexes is compared. Chapter 1 describes a brief history of redox-active ligands. The previously published results of redox-active ligands acting as an electron source are discussed. In Chapter 2, the synthesis and electronic and structural properties of metal dichlorides and trichlorides of Group 5 metal complexes incorporating the [ONO] ligand and comparing the metal-ligand cooperativity are performed. In Chapter 3, the synthesis and reactivity of [ONO]NbMe2 and the reactivity of reduced species of [ONO]V(L)n are discussed.

Book Polynuclear Iron oxygen Complexes

Download or read book Polynuclear Iron oxygen Complexes written by Kingsley Leonard Taft and published by . This book was released on 1993 with total page 672 pages. Available in PDF, EPUB and Kindle. Book excerpt: