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Controlled Synthesis of Carbon Nanotubes Using Chemical Vapor Deposition Methods
Published in Ahmed Busnaina, Nanomanufacturing HANDBOOK, 2017
Rao et al. report the growth of carbon nanotubes through the vapor phase delivery of metal-organic catalyst precursors.49 In their experiment, various metal-organic catalysts such as ferrocene, cobaltocene, or nickelocene, containing both the transition metals (Fe, Co, and Ni) and hydrocarbon species, were used in a reductive atmosphere to produce carbon nanotubes. Based on the above result, a simple and economic way for producing bulk quantities of carbon nanotubes was developed by Andrews et al. using CVD through the catalytic decomposition of a ferrocene [Fe(C5H5)2)–xylene (C8H10)] mixture at 675°C over quartz substrate in a tube reactor.50
Synthesis and electronic structure of a series of first-row transition-metal pyrazine(diimine) complexes in two oxidation states
Published in Journal of Coordination Chemistry, 2022
Daniela Sanchez Arana, Jaylan R. Billups, Bruno Donnadieu, Sidney E. Creutz
The putative manganese(II) pyrazine(diimine) complex (DiPPPZDI)MnBr2 was prepared from the reaction of MnBr2(THF)2 and DiPPPZDI in toluene at 70 °C over 48 h. The resulting complex, isolated as a pale yellow-orange solid, is sparingly soluble in toluene or benzene and highly soluble in dichloromethane. The 1H NMR spectrum in CD2Cl2 shows only extremely broad resonances between −20 to +30 ppm. Unfortunately, the compound seems to have only limited stability, and even under inert atmosphere and in non-coordinating solvents such as toluene or dichloromethane decomposition becomes quickly evident, with increasing amounts of free ligand becoming detectable by NMR along with the precipitation of an insoluble solid. Upon attempting to dissolve the compound in coordinating solvents such as THF, an immediate color change from yellow-orange to nearly colorless is observed with concomitant precipitation of a white solid, which may be MnBr2(THF)2. These stability issues have prevented us from fully characterizing analytically pure samples of the compound. We do observe that the compound is readily reduced by cobaltocene in toluene or diethyl ether, giving a new, deep red paramagnetic species (see Supporting Information); this suggests that the redox potential of the compound is not more negative than about −1.3 V versus Fc/Fc+ [30]. This reduced product has not yet been isolated in pure form or characterized in detail.