Ethylene oligomerization in metal–organic frameworks bearing nickel(<scp>ii</scp>) 2,2'-bipyridine complexes [electronic resource].
- Published:
- Washington, D.C. : United States. Dept. of Energy. Office of Basic Energy Sciences, 2017.
Oak Ridge, Tenn. : Distributed by the Office of Scientific and Technical Information, U.S. Dept. of Energy - Physical Description:
- pages 351-367 : digital, PDF file
- Additional Creators:
- United States. Department of Energy. Office of Basic Energy Sciences
United States. Department of Energy. Office of Scientific and Technical Information - Access Online:
- www.osti.gov
- Summary:
- <p>Here, the metal–organic frameworks Zr<sub>6</sub>O<sub>4</sub>(OH)<sub>4</sub>(bpydc)<sub>6</sub>(<bold>1</bold>; bpydc<sup>2–</sup>= 2,2'-bipyridine-5,5'-dicarboxylate) and Zr<sub>6</sub>O<sub>4</sub>(OH)<sub>4</sub>(bpydc)<sub>0.84</sub>(bpdc)<sub>5.16</sub>(<bold>2</bold>; bpdc<sup>21458983 </sup>= biphenyl-4,4'-dicarboxylate) were readily metalated with Ni(DME)Br<sub>2</sub>(DME = dimethoxyethane) to produce the corresponding metalated frameworks<bold>1</bold>(NiBr<sub>2</sub>)<sub>6</sub>and<bold>2</bold>(NiBr<sub>2</sub>)<sub>0.84</sub>. Both nickel(<sc>ii</sc>)-containing frameworks catalyze the oligomerization of ethylene in the presence of Et<sub>2</sub>AlCl. In these systems, the pore environment around the active nickel sites significantly influences their selectivity for formation of oligomers over polymer. Specifically, the single-crystal structure of<bold>1</bold>(NiBr<sub>2</sub>)<sub>5.64</sub>reveals that surrounding metal–linker complexes enforce a steric environment on each nickel site that causes polymer formation to become favorable. Minimizing this steric congestion by isolating the nickel(<sc>ii</sc>) bipyridine complexes in the mixed-linker framework<bold>2</bold>(NiBr<sub>2</sub>)<sub>0.84</sub>markedly improves both the catalytic activity and selectivity for oligomers. Furthermore, both frameworks give product mixtures that are enriched in shorter olefins (C<sub>4–10</sub>), leading to deviations from the expected Schulz–Flory distribution of oligomers. Although these deviations indicate possible pore confinement effects on selectivity, control experiments using the nickel-treated biphenyl framework Zr<sub>6</sub>O<sub>4</sub>(OH)<sub>4</sub>(bpdc)<sub>6</sub>(NiBr<sub>2</sub>)<sub>0.14</sub>(<bold>3</bold>(NiBr<sub>2</sub>)<sub>0.14</sub>) reveal that they likely arise at least in part from the presence of nickel species that are not ligated by bipyridine within<bold>1</bold>(NiBr<sub>2</sub>)<sub>5.64</sub>and<bold>2</bold>(NiBr<sub>2</sub>)<sub>0.84</sub>.</p>
- Subject(s):
- Note:
- Published through SciTech Connect.
02/22/2017.
Faraday Discussions 201 ISSN 1359-6640; FDISE6 AM
Miguel I. Gonzalez; Julia Oktawiec; Jeffrey R. Long.
Univ. of Minnesota, Minneapolis, MN (United States) - Funding Information:
- FG02-12ER16362
SC0008688
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