Download or read book Synthesis Electrochemical and Electrocatalytic Properties of Transition Metal Complexes Based on Cyclohexane supported Bis imino Pyridines written by Simon Child and published by . This book was released on 2017 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Synthesis Electronic Delocalization and Applications of Octahedral Bis imino pyridine Group 13 Metal Complexes written by Amela Arnold (Drljevic) and published by . This book was released on 2020 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation discusses the synthesis, characterization and electronic delocalization of bis(imino)pyridine (I2P) complexes of the Group 13 metals Al, Ga and In. This work aims to understand the electronic communication between redox-active ligands bridged by a main group metal and apply this research for storing multiple electrons in nonaqueous redox-flow battery applications. The introduction to this dissertation details the background on redox-active ligands, mixed valency and redox flow batteries. A future outlook on this field is presented. The work presented here has contributed to our understanding of delocalization of charge in organic molecules, and how delocalization is affected by increasing charge, appending electron-donating or withdrawing functional groups or varying the metal bridge. Evidence for a symmetric nonaqueous redox flow battery is presented. In Chapter 2, ligand-based mixed valency is introduced. Water stable organic mixed valence (MV) compounds were prepared by reaction of reduced bis(imino)pyridine ligands (I2P) with the trichloride salts of Al, Ga, and In. Coordination of two tridentate ligands to each ion affords octahedral complexes that are accessible with five ligand charge states: [(I2P0)(I2P−)M]2+, [(I2P−)2M]+, (I2P−)(I2P2−)M, [(I2P2−)2M]−, [(I2P2−)(I2P3−)M]2−, and for M = Al only, [(I2P3−)2M]3−. In solid-state structures the anionic members of the redox series are stabilized by intercalation of Na+ cations within the ligands. The MV members of the redox series, (I2P−)(I2P2−)M and [(I2P2−)(I2P3−)M]2−, show characteristic intervalence transitions, in the near-infrared region between 6800 - 7400 and 7800 - 9000 cm-1, respectively. Cyclic voltammetry (CV), NIR spectroscopic, and X-ray structural studies support the assignment of Class II for compounds [(I2P2−)(I2P3−)M]2− and Class III for M = Al and Ga in (I2P−)(I2P2−)M. All compounds containing a singly reduced I2P− ligand exhibit a sharp, low energy transition in the region 5100 - 5600 cm−1 that corresponds to a [pi]* - [pi]* transition. CV studies demonstrate that the electron transfer events in each of the redox series, Al, Ga, and In span 2.2, 1.4 and 1.2 V, respectively. In Chapter 3, ligand-based mixed valent (MV) complexes of Al(III) incorporating electron donating (ED) and electron withdrawing (EW) substituents on bis(imino)pyridine ligands (I2P) are presented. The MV states (I2P−)(I2P2−)Al and [(I2P2−)(I2P3−)Al]2− prepared containing EW groups are both assigned as Class II/III. The MV states prepared with incorporation of ED functional groups are Class III and Class II/III in the (I2P−)(I2P2−)Al and [(I2P2−)(I2P3−)Al]2− charge states, respectively. The assignments of the delocalized electronic structures were made using cyclic voltammetry (CV), and near infra-red (NIR) spectroscopy. The MV ligand charge states (I2P−)(I2P2−)Al and [(I2P2−)(I2P3−)Al]2− show intervalence charge transfer (IVCT) transitions at 6850-7740 and 7410-9780 cm−1, respectively. Alkali metal cations in solution had no effect on the IVCT bands of [(I2P2−)(I2P3−)Al]2− complexes containing ED -PhNMe2 substituents or EW -PhF5 substituents on the I2P ligands. Localization of charge in [(I2P2−)(I2P3−)Al]2− was observed when -PhOMe substituents are included on the I2P ligands, so that those complexes are Class II/III with K+ and Class III with K:(18-crown-6)+. In Chapter 4, the application of these redox-active octahedral Al(III) complexes as analytes for symmetric nonaqueous redox flow batteries is presented. Redox flow batteries (RFBs) operate by storing electrons on soluble molecular anolytes and catholytes, however large increases in the energy density of RFBs could be achieved if multiple electrons could be stored in each molecular analyte. Others have suggested and employed various transition element - redox active ligands combinations to realize multi-electron storage in anolytes, and a challenge with those efforts has been the analyte's stability over extended charging and discharging of multi-electron cycles. We reported an organoaluminum analyte in which four electrons can be stored on organic ligands, and for which charging and discharging cycles performed in a symmetric nonaqueous RFB configuration remain stable for over 100 cycles at 70% state of charge and 97% Coulombic efficiency. Stability is promoted by the kinetic inertness of the anolyte to trace water in solvents and by the redox stability of the Al(III) ion to the applied current. Proof-of principle experiments performed with an asymmetric NRFB configuration further demonstrate that up to four electrons can be stored in the cell with no degradation of the analyte over multiple cycles that show 96% Coulombic efficiency.

Download or read book Synthesis and Properties of Transition Metal Complexes written by Jay W. Wrathall and published by . This book was released on 1962 with total page 334 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Facile Preparation of Bis imino pyridine Complexes Via Mechanochemistry and Inorganic Synthons Via Benign Reductants written by Thomas E. Shaw IV and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis is comprised of two key themes: (i) leveraging mechanochemical synthetic methods for the green preparation of bis(imino)pyridine ligands and associated first row transition metal coordination complexes, and (ii) the preparation and characterization of both historic and novel mid-valent inorganic synthons via the use of dimethylphenylsilane as a stoichiometric reducing agent. The first portion of this thesis highlights the utilization of solvent-free vibratory ball-milling in lieu of traditional, solvent-based refluxes. A variety of both bis(imino)pyridine ligands and complexes were formed in drastically reduced timeframes with solvent-economical work-up procedures. This methodology was also leveraged for the isolation of acetyl(imino)pyridine ligands which, in turn, provided direct access to an unsymmetrical bis(imino)pyridine ligand in good yield. The second portion of this thesis is centered on the preparation of ether-coordinated, mid-valent, early transition metal chloride precursors. First, well-established, reproducible syntheses and characterization libraries were developed for the classic molybdenum(IV) and tungsten(IV) chloride diethyl ether- and dimethoyxethane-coordinated synthons. Then, the utilization of commercially available dimethylphenylsilane as a stoichiometric reducing agent provided direct access to single crystals of the classic edge-sharing bioctahedral dimer Mo2Cl6(dme)2, whose single crystal x-ray structure and electronic structure had remained ambiguous for nearly 40 years. This work laid the foundation for the preparation of intriguingly reactive, uncoordinated, mid-valent binary chlorides of the heavier Group 5 and Group 6 transition metals. Utilization of the acquired binary chlorides resulted in both less expensive, easier routes to traditional synthons and the formation of novel, ether-coordinated complexes of niobium and tantalum. Synthesis, characterization, and computational studies are presented and discussed.

Download or read book Design and Synthesis of a Series of Redox Active Tetrazine and Triazine Based Transition Metal Complexes written by Yixin Zhang and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The use of two different chelating redox active ligands, 2,6-bis(6-methyl-1,2,4,5-3-yl) pyridine (BTZP) and 2,6-bis-(5,6-dialkyl-1,2,4-triazin-3-yl)-pyridine (BTP) in heterometallic first row and second row transition metal chemistry has yielded two new families of redox active metal complexes. These complexes were found to exhibit interesting electrochemical and magnetic properties. In this thesis, Chapter 1 lays the foundation for the research presented within. This section covers the fundamentals of the ligand design, ligand synthesis and related coordination chemistry literature review. Chapters 2 and 3 report the results of the current thesis. In Chapter 2, the synthesis and characterization of a family of discrete molecules and supramolecular arrangements, employing the ligand BTZP, is presented. All of the complexes presented in Chapter 2 are successfully synthesized and characterized with electrochemical and magnetic studies. According to the electrochemical data, it is found that the classic "terpy-like" complexes with [Co(BTZP) 2]2+ formula fosters more stability in the redox process. In Chapter 3, a family of transition metal complexes with [M(BTP) 2]2+ (M=Fe or Co) inorganic cores were obtained through the employment of the ligand BTP with various anions. In addition, dimeric molecules with [CoX4(BTP)2] formula were also obtained by solvothermal synthesis. The complexes were also electrochemically characterized, with all the complexes capable of being reduced, while only [CoII(BTP)2] (ClO4)2 showed reversible redox process. Similar with BTZP, the series of BTP based complexes are also characterized through magnetic measurement. Only cobalt-based BTP complexes are paramagnetic, with [CoII(BTP)2]2+ being spin crossover active when BF4- and ClO4- are present. However, the presence of NCS- and halides lead to either antiferromagnetic interactions and ferromagnetic interactions dominating at different temperature regimes.

Download or read book Rational Design Synthesis and Characterization of Amide Functionalized Pyridine and Benzimidazole Transition Metal Complexes written by Samuel S. K. Asem and published by . This book was released on 2011 with total page 576 pages. Available in PDF, EPUB and Kindle. Book excerpt: This study expands our efforts to make a new class of Pt (II) compounds analogous to cisplatin and its derivatives using sterically hindered ligands. Pt compounds in this series have been synthesized using specially designed pyridine and benzimidazole ligands. These heterocycles, amide functionalized at position 2 with aryl and alkyl pendants, rapidly change their mode of coordination depending on the pH of the medium. These ligands, synthesized using condensation chemistry, also coordinate to Co(II), Ni(H), Cu(lI), and Zn(1I) generally as anionic bis-chelates through the benzimidazole nitrogen and the carbonyl oxygen, creating a four-coordinate complex with the exception of an unusual trigonal bipyramidal Zn(H) complex. I H NMR temperature studies reveal that these ligands interconvert between imide and amide isomers and that electron withdrawing pendants favor amide isomers. Crystal structures of Co(II) and Ni(1I) complexes of N-( I-methylbenzimidazol-2-yl)cyclohexanecarboxamide, for example, show two ligands bind per metal ion when reacted with acetate and nitrate salts. The bischelates of these Ni(1I) complexes also show expansions of their coordination spheres from four to five-coordinate. Furthermore, these Ni(II) bis-chelated complexes possess square planar or distorted 4-coordinate geometries. The synthesis and properties of several new Pt (II) complexes containing these ligands will be presented. A second generation and novel complex class containing metal-binding, linker and recognition domains is reported. Both classes of Pt complexes were obtained using a synthetic methodology which favors the cis isomers. The second generation complex crystallizes in the monoclinic space group P2dn with lattice dimensions a = 17.7393(5) A, b = 11.4632(3) A, c = 19.3959(5) A and ~ = 99.794(3)°. These complexes have been characterized using physical methods that include X-ray crystallography, IH &13C NMR, Mass spectrometry, UV and IR spectroscopies. Complexes similar in structure to cisplatin and carboplatin show varying cytotoxic properties toward different cancer cell lines. Additionally, some of these new Pt complexes show comparable and promising cytotoxicity against prostate cancer cell lines.

Download or read book Reduced Bis Imino pyridine Iron and Manganese Complexes written by Sarah Kathleen Russell and published by . This book was released on 2011 with total page 313 pages. Available in PDF, EPUB and Kindle. Book excerpt: The synthesis, electronic structures and reactivity of bis(imino)pyridine iron and manganese complexes were investigated. A series of dimeric bis(imino)pyridine iron dinitrogen compounds was prepared by reduction of the corresponding iron dihalide complexes with sodium naphthalenide. The dinitrogen compounds were shown to have electronic structures similar to the monomeric bis(imino)pyridine iron bis(dinitrogen) compound, (iPrPDI)Fe(N2). Evaluation of the catalytic olefin hydrogenation activity of the new dinitrogen compounds revealed a significant improvement in rate over (iPrPDI)Fe(N2), which was attributed to the smaller substituents on the bis(imino)pyridine aryl groups. The reactivity of the bis(imino)pyridine iron dinitrogen compounds with diazoalkanes was investigated. For all of the iron dinitrogen compounds, diazoalkane N-N bond cleavage was observed with monosubstituted diazoalkanes. Addition of diphenyldiazomethane to smaller bis(imino)pyridine iron dinitrogen compounds furnished bis(imino)pyridine iron carbene complexes. A combination of 1H NMR, Mössbauer and X-ray absorption spectroscopies, SQUID magnetometry and X-ray diffraction was used to propose several possible electronic structures for the bis(imino)pyridine iron carbene complexes. The spectroscopic data most strongly supported an electronic structure having an intermediate spin iron(III) center and a one-electron reduced bis(imino)pyridine chelate. The bis(imino)pyridine iron carbene complexes underwent carbene transfer to carbon monoxide and aryl azides, but not cyclopropanation or olefin metathesis reactions. The bis(imino)pyridine iron dinitrogen compounds were also found to be competent catalysts for carbon-carbon bond forming catalysis. Addition of ethylene to butadiene in the presence of 5 mol% iron catalyst resulted in a [2[pi] + 2[pi]] cycloaddition to furnish vinylcyclobutane, while addition of ethylene to isoprene under the same conditions resulted in 1,4hydrovinylation to yield 5-methyl-1,4-hexadiene. Under similar reaction conditions, [(MePDI)Fe(N2)]2([mu]2-N2) also catalyzed the cycloisomerization of 1,5-hexadiene. Finally, syntheses of variations of the bis(imino)pyridine iron dinitrogen compounds were investigated. Reduction of a bis(aldimino)pyridine iron dibromide did not afford an iron dinitrogen compound, but instead gave a diiron compound. Modeling variable temperature SQUID data for this compound provided experimental evidence for the redox activity of the bis(aldimino)pyridine ligand. The reduction of a bis(imino)pyridine manganese dichloride also did not afford a dinitrogen complex, but instead resulted in a bis(tetrahydrofuran) compound.

Download or read book Synthesis and Characterization of Transition Metal Complexes of 2 2 pyridyl benzimidazole and 2 6 bis benzimidazolyl pyridine written by Frank L. Messana and published by . This book was released on 1999 with total page 80 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Synthesis Characterization and Reactivity Study of Bis Imino N Heterocyclic Carbene Transition Metal Complexes written by Jameel Raddah Al-Thagfi and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Synthesis of Early Transition Metal Complexes Supported by Pyrrolyl and Indolyl Based Ligands written by Christopher R. Yeisley and published by . This book was released on 2013 with total page 68 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Synthesis Characterization and Applications of Pyridine and Pyridol based Azamacrocyclic Transition Metal Complexes written by Hannah May Johnston and published by . This book was released on 2018 with total page 298 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Preparing and Characterizing Bis imino pyridine Complexes of Nickel Iron and Cobalt for Electrocatalytic Hydrogen Evolution written by Samuel J. Underwood and published by . This book was released on 2016 with total page 63 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Bis imino pyridine Iron and Cobalt Complexes written by Amanda Catherine Bowman and published by . This book was released on 2010 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The synthesis, reactivity and electronic structures of a series of bis(imino)pyridine iron and cobalt complexes was investigated. A series of monomeric bis(imino)pyridine cobalt dinitrogen complexes was investigated using a combination of 1H NMR and infrared spectroscopies, X-ray crystallography, EPR spectroscopy, solution and solid state magnetic measurements and density functional theory. The neutral bis(imino)pyridine cobalt dinitrogen complexes have doublet ground states and are best described as low-spin cobalt(I) centers with an unpaired electron on the singly reduced chelate, while the anionic bis(imino)pyridine cobalt dinitrogen complexes are also best described as low-spin cobalt(I) centers with dianionic chelates. These investigations established that reduction of monochloride precursors occurs at the metal center, in contrast to the related bis(imino)pyridine iron bis(dinitrogen) complex, (iPrPDI)Fe(N2)2, where reduction of the chelate is observed. A series of bis(imino)pyridine iron imide complexes was also investigated. A combination of Xray crystallography, variable temperature SQUID magnetization data and Mössbauer spectroscopy was used to elucidate the electronic structures of these complexes. In contrast to the previously reported N-aryl substituted bis(imino)pyridine iron imide complexes, where an iron(III) metal center and a singly reduced chelate was observed, an iron(IV) metal center and a triplet diradical chelate was observed for N-alkyl substituted bis(imino)pyridine iron imide complexes. For (iPrPDI)FeN(2Ad) (iPrPDI = 2,6-(2,6-iPr2-C6H3-N=CMe)2C5H3N), thermal spin crossover from S = 0 to S = 1 was observed when warming from 15 K to 200 K. (ArPDI)FeNR compounds with an S = 0 ground state promoted C-H bond activation of both imine methyl groups of the bis(imino)pyridine ligand. The C-H bond activation with (iPrPDI)FeN(CyOct) was firstorder in iron with a rate constant of k = 3.4(2)x10-5 s-1 at 25 °C and a primary kinetic isotope effect of 3.3(2), consistent with a rate-determining step of intramolecular C-H bond activation. In contrast, no C-H bond activation of the ligand was observed for the iron imide complexes that are S = 1 at 23 °C. The reactivity of bis(imino)pyridine iron imide compounds with hydrogen, silanes, terminal alkynes and organic azides, and the electronic structures of the resulting iron complexes, was also investigated.

Download or read book Electrochemical and Catalytic Properties of Transition Metal schiff Base Complexes written by and published by . This book was released on 2001 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Synthesis and Characterization of Transition Metal Complexes as Well as Their Application in the Formation of Metal based Materials and the Investigation of Their spectro electrochemical Behavior written by Andrea Preuß and published by . This book was released on 2020 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Early Transition Metal Complexes of Pyridine Derivatives written by Eugene Chong and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Metals and Metal Based Electrocatalytic Materials for Alternative Energy Sources and Electronics written by Jasmina Stevanovic and published by Nova Science Publishers. This book was released on 2019 with total page 542 pages. Available in PDF, EPUB and Kindle. Book excerpt: The important role of metals, their oxides and catalytically-interactive supports in contemporary investigations related to rational construction of next-generation devices as alternative energy sources and hi-tech electronics is ambitiously presented throughout this book. The topics involve: Carbonaceous and non-typical platinum-based nanostructured electrode materials as promising candidates for anodic reactions in low-temperature fuel cells. Ruthenium oxide as electroactive material, presented through its innovative synthesis routes involving microwave heating and ultrasonic spray pyrolysis, with the focus on its performances as an electrochemical supercapacitor, but also as a part of multicomponent electrode coating in electrocatalysis of chlorine and oxygen evolution. Alkaline water electrolysis as the simplest method for hydrogen production especially when using renewable energy sources, offering the advantage of simplicity and environmentally clean technology with zero emission of greenhouse gases. New frontiers in electroconductive composite materials and biopolymers combined with noble metal nanoparticles that can be used in nanoelectronics and medical nanotechnologies. The possibilities for the operational improvement of an aluminum-air battery presented through alternative modifications of an Al-anode by alloying with magnesium and electromagnetic bulk structure homogenization. The improvements of copper-based materials as well as the research toward sustainable production of copper itself as an important component for further development of electronic devices.