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Title: Metal encapsulating carbon nanostructures from oligoalkyne metal complexes

Abstract

Carbon nanotubes, onions, and related closed-shell carbon particles have commanded extensive recent attention because of their potential applications as unique electronic, magnetic, and mechanically robust materials. When filled with metals, such nanocapsules have additional promise as magnetic particles, contrasting agents, protecting cloaks, and catalysts and in other applications. Among the various methods for their preparation, the transition metal (especially Fe, Co, and Ni) catalyzed pyrolysis of small organic molecules has shown promise for larger scale production and in structural control. While the use of organometallic complexes as solid catalyst precursors or copyrolytic gaseous ingredients has been reported, all of these studies have been limited to gas-phase experiments at relatively high temperatures. There is very little literature that deals with the organic solid-state generation of carbon nanotubes. The latter suffers from extreme conditions, poor yields, or not readily modifiable starting materials. Development of synthetic organic approaches to closed shell large carbon structures is desirable but in its infancy. Here the authors present a significant step in its progress.

Authors:
; ; ; ;
Publication Date:
Research Org.:
Univ. of California, Berkeley, CA (US); Lawrence Berkeley National Lab., CA (US)
Sponsoring Org.:
USDOE; National Science Foundation (NSF)
OSTI Identifier:
20013690
DOE Contract Number:
AC03-76SF00098
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of the American Chemical Society; Journal Volume: 121; Journal Issue: 44; Other Information: PBD: 10 Nov 1999
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; CARBON; TUBES; USES; PYROLYSIS; TRANSITION ELEMENTS; ENCAPSULATION

Citation Formats

Dosa, P.I., Erben, C., Iyer, V.S., Vollhardt, K.P.C., and Wasser, I.M. Metal encapsulating carbon nanostructures from oligoalkyne metal complexes. United States: N. p., 1999. Web. doi:10.1021/ja9924602.
Dosa, P.I., Erben, C., Iyer, V.S., Vollhardt, K.P.C., & Wasser, I.M. Metal encapsulating carbon nanostructures from oligoalkyne metal complexes. United States. doi:10.1021/ja9924602.
Dosa, P.I., Erben, C., Iyer, V.S., Vollhardt, K.P.C., and Wasser, I.M. 1999. "Metal encapsulating carbon nanostructures from oligoalkyne metal complexes". United States. doi:10.1021/ja9924602.
@article{osti_20013690,
title = {Metal encapsulating carbon nanostructures from oligoalkyne metal complexes},
author = {Dosa, P.I. and Erben, C. and Iyer, V.S. and Vollhardt, K.P.C. and Wasser, I.M.},
abstractNote = {Carbon nanotubes, onions, and related closed-shell carbon particles have commanded extensive recent attention because of their potential applications as unique electronic, magnetic, and mechanically robust materials. When filled with metals, such nanocapsules have additional promise as magnetic particles, contrasting agents, protecting cloaks, and catalysts and in other applications. Among the various methods for their preparation, the transition metal (especially Fe, Co, and Ni) catalyzed pyrolysis of small organic molecules has shown promise for larger scale production and in structural control. While the use of organometallic complexes as solid catalyst precursors or copyrolytic gaseous ingredients has been reported, all of these studies have been limited to gas-phase experiments at relatively high temperatures. There is very little literature that deals with the organic solid-state generation of carbon nanotubes. The latter suffers from extreme conditions, poor yields, or not readily modifiable starting materials. Development of synthetic organic approaches to closed shell large carbon structures is desirable but in its infancy. Here the authors present a significant step in its progress.},
doi = {10.1021/ja9924602},
journal = {Journal of the American Chemical Society},
number = 44,
volume = 121,
place = {United States},
year = 1999,
month =
}
  • The reactions of transition-metal hydrides with metal alkynyl compounds are virtually unexplored. The only previous systematic study is Lukehart's synthesis of bridging vinylidene complexes from formal addition of a Pt-H bond across the carbon-carbon triple bond of several metal alkynyl compounds. Davison and Selegue have shown that unsaturated carbon ligands bonded to late transition metals generally undergo ..beta..-attack by electrophiles and ..cap alpha..-attack by nucleophiles. This suggested that metal vinylidene complexes might be formed by proton transfer from metal hydrides to metal alkynyl complexes. This communication reports the first kinetic and thermodynamic measurements on this type of reaction and providesmore » evidence that certain ruthenium alkynyl complexes are remarkably strong carbon-centered bases.« less
  • The mechanism describing the displacement of a paramagnetic metal complex by (1) an identical complex or (2) a greatly dissimilar radical is reviewed. In the first system, a concerted homolytic displacement has been well established as the path; in the second system, a 2-stage process in which and electron transfer followed by a heterolytic displacement may take place. Appropriate experiments to provide data needed to select the correct mechanism are discussed. 1 table.
  • Zeolite-supported ruthenium catalysts for the hydrogenation of carbon monoxide and carbon dioxide have been prepared by sorbing Ru(CO)/sub 5/ (molecular diameter 6.3 /angstrom/) onto Na-Y zeolite and Linde 5A molecular sieve. Although the metal carbonyl is not absorbed into the pores of the molecular sieve, it is readily absorbed into the pores and supercages of the Na-Y zeolite. Slow, temperature-programmed heating of the Ru/sub 3/(CO)/sub 12/ in Na-Y to 350/degree/C under a flow of hydrogen results in decarbonylation and formation of a CO hydrogenation catalyst that produces a very atypical (for ruthenium) hydrocarbon distribution truncated at about C/sub 10/. Themore » unusual product distribution presumably arises because the catalyst sites are situated within the zeolite supercages. Thus the metal is highly dispersed and/or the growing hydrocarbon chains are subject to geometrical limitations on their growth. Consistent with this hypothesis, ruthenium carbonyl clusters immobilized on the external surfaces of Na-Y zeolite, Linde 5A molecular sieve, and /gamma/-alumina all exhibit typical, nonselective hydrocarbon product distributions. The same supported ruthenium carbonyl clusters are also extremely active catalysts for the selective hydrogenation of CO/sub 2/(H/sub 2/:CO/sub 2/ = 4:1) to methane. At a lower H/sub 2/:CO/sub 2/ ratio (1:1), however, Na-Y supported Ru/sub 3/(CO)/sub 12/ catalyzes the hydrogenation of CO/sub 2/ to higher hydrocarbons as well (up to C/sub 16/). It is proposed that CO/sub 2/ is reduced to CO and that hydrogenation of both proceeds by the same mechanism. 21 references, 2 figures, 4 tables.« less
  • The hierarchically porous nitrogen-doped carbon materials, derived from nitrogen-containing isoreticular metal-organic framework-3 (IRMOF-3) through direct carbonization, exhibited excellent electrocatalytic activity in alkaline solution for oxygen reduction reaction (ORR). This high activity is attributed to the 10 presence of high percentage of quaternary and pyridinic nitrogen, the high surface area as well as good conductivity. When IRMOF-3 was carbonized at 950 °C (CIRMOF-3-950), it showed four-electron reduction pathway for ORR and exhibited better stability (about 78.5% current density was maintained) than platinum/carbon (Pt/C) in the current durability test. In addition, CIRMOF-3-950 presented high selectivity to cathode reactions compared to commercial Pt/C.