Download or read book Mono and Trimetallic Cobalt II and Monometallic Cobalth III Amine bis phenolate Complexes written by Uttam Kumar Das and published by . This book was released on 2010 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Synthesis and Reactivity Studies of Mono Bi and Trimetallic Complexes Supported by Oxidatively resistant Polyanionic Ligands written by Julia Megan Stauber and published by . This book was released on 2017 with total page 296 pages. Available in PDF, EPUB and Kindle. Book excerpt: Investigations of the oxidatively-resistant hexacarboxamide cryptand, mBDCA-5t-H6, to support mono-, bi-, and trimetallic complexes are presented. Selective single metal ion insertion into the cryptand was achieved to generate the mono-Co(II) and Zn(II) complexes that contain proximal hydrogen-bonding networks enforced by the carboxamide N–H groups of the pre-organized second-coordination sphere. The cobalt(II) complex serves as a selective colorimetric turn-on fluoride sensor and represents a unique example of a transition-metal based fluoride sensor where fluoride binding takes place directly at the transition metal. The binding of fluoride is synergistic involving hydrogen-bond donors from the second-coordination sphere together with metal(II) ion coordination. Isolation of the mono-metallic Co and Zn complexes allowed for the preparation of their transition and main group metal heterobimetallic variants. Hetero- and homobimetallic complexes of cobalt(II) and zinc(II) are presented, and the reactivity of the homobimetallic complexes with O2, O−2 , and H2O2 is discussed. The cryptand was also explored as a supporting ligand for cofacially arranged divalent group 14 ions (Ge, Sn, Pb). Reaction of the di-tin(II) complex with elemental sulfur or selenium generates di-tin polychalcogenide complexes containing [mu]–E and bridging [mu]– E5 ligands (E = Se, S), where the sulfur-containing product acts reversibly as a source of S3 ∙− in DMF solution. The di-tin(II) complex also serves as a bidentate ligand for the preparation of trimetallic Sn2/M complexes (M = Ag(I), Au(I), Pd(0)). Reactivity studies of the Sn2/Pd(0) complex with substrates including CS2, S8, and 1AdC≡P are described. Terminal titanyl complexes supported by oxidatively-resistant tri- and tetrametaphosphates were prepared as molecular models of heterogeneous oxidation catalysts. These complexes react with hydrogen peroxide to produce the corresponding peroxotitanium( IV) metaphosphates, and represent rare examples of titanium oxo and peroxo systems supported by an all-oxygen ligand environment.

Download or read book Cobalt and Chromium Amino bis phenolate Complexes for Epoxide Homopolymerization and Copolymerization with Carbon Dioxide written by Kenson Ambrose and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Chemical transformations of CO2 into useful materials have received significant attention in the past as it is a potential C1 feedstock of very high abundance. This attention originates from the increased abundance of CO2 in the earth's atmosphere due to anthropogenic processes such as fossil fuel combustion. The use of CO2 as a C1 feedstock will not lead to a decrease in atmospheric CO2 concentrations but rather as an alternative starting material to petroleum derived small molecules. Metal-catalyzed reactions of CO2 with epoxides into either polycarbonate via copolymerization or cyclic carbonates via cycloaddition are potentially lucrative methods for CO2 use. In this work, Co(II)/(III) complexes bearing tripodal amino-bis(phenolate) ligands were synthesized and characterized by NMR, MALDI-TOF mass spectrometry, elemental analysis and X-ray diffraction, then investigated for catalytic activity toward CO2 and epoxide coupling in the presence of the following co-catalysts: TBAB (tetrabutylammonium bromide), PPNCl (bis(triphenylphosphine)iminium chloride) or DMAP (4-dimethylaminopyridine). Co(III) complexes also contained ancillary ligands such as [2,4-DNP]− (2,4-dinitrophenolate), OAc− (acetate) and −O2CCF3 (trifluoroacetate) and showed selectivity toward cyclic carbonate production. A Co(II) complex, however, contained coordinated KOAc (observed via X-ray diffraction and elemental analyses) and was selective toward polycarbonate production where OAc− served as a minor initiator during the copolymerization process, as determined by end-group analysis using MALDI-TOF mass spectrometry. The coordinated KOAc is believed to play an important role in overall catalyst activity as other reported catalysts with similar structure, but not containing KOAc, showed little to no copolymerization. Cr(III) complexes bearing slightly different amino-bis(phenolate) ligands were also synthesized and investigated as catalyst for reactions of CO2 with epoxides. A Cr(III) complex with a ligand containing tert-butyl groups in the ortho and para positions of the phenolate O-donors, was highly active toward CHO (cyclohexene oxide) ring-opening homopolymerization to produce high molecular weight PCHO (poly(cyclohexene oxide)) without the use of a co-catalyst and even in the presence of CO2. Modification of this complex by introducing methyls into the ortho and para positions of the phenolate donors switched activity to CHO/CO2 copolymerization, with high selectivity and CO2 incorporation. This complex showed the fastest rate of CO2/epoxide copolymerization with PPNN3 as a co-catalyst, when monitored using in situ FTIR spectroscopy. Kinetics studies of the CHO/CO2 copolymerization process showed a first order dependence on catalyst concentration.

Download or read book Synthesis and Characterization of Cobalt II Nickel II and Copper II Complexes with 3 3 bis p X benzoylacetoneiminato bis trimethylene amine Ligands written by Yu-Ying Chen and published by . This book was released on 1979 with total page 128 pages. Available in PDF, EPUB and Kindle. Book excerpt: