Controlling structure and reactivity in cationic Solid–State Molecular OrganoMetallic (SMOM) systems using anion templating
The role that the supporting anion has on the stability, structure and catalytic performance, in Solid-state Molecular Organ-oMetallic systems (SMOM) based upon [Rh(Cy2PCH2CH2PCy2)(η2η2-NBD)][BArX4], [1-NBD][BArX4], is reported (X = Cl, F, H; NBD = norbornadiene). The tetra–aryl borate anion is syst...
| Main Authors: | , , , , , , , |
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| Format: | Journal article |
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American Chemical Society
2018
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| _version_ | 1797102160446488576 |
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| author | McKay, A Martinez-Martinez, A Griffiths, H Rees, N Waters, J Weller, A Krämer, T Macgregor, S |
| author_facet | McKay, A Martinez-Martinez, A Griffiths, H Rees, N Waters, J Weller, A Krämer, T Macgregor, S |
| author_sort | McKay, A |
| collection | OXFORD |
| description | The role that the supporting anion has on the stability, structure and catalytic performance, in Solid-state Molecular Organ-oMetallic systems (SMOM) based upon [Rh(Cy2PCH2CH2PCy2)(η2η2-NBD)][BArX4], [1-NBD][BArX4], is reported (X = Cl, F, H; NBD = norbornadiene). The tetra–aryl borate anion is systematically varied at the 3,5–position, ArX= 3,5-X2C6H3, and the stability and structure in the solid–state compared with the previously reported [1-NBD][BArCF34] complex. Single crystal X-ray crystallography shows that the three complexes have different packing motifs, in which the cation sits on the shared face of two parallelepipeds for [1-NBD][BArCl4], is surrounded by eight anions in gyrobifastigium arrangement for [1-NBD][BArF4], or the six anions show an octahedral cage arrangement in [1-NBD][BArH4], similar to [1-NBD][BArCF34]. C-X···X-C contacts, commonly encountered in crystal–engineering, are suggested to be important in determining structure. Addition of H2 in a solid/gas reaction affords the resulting –alkane complexes, [Rh(Cy2PCH2CH2PCy2)(η2η2-NBA)][BArX4] [1-NBA][BArX4] (NBA = norbornane), which can then proceed to lose the alkane and form the zwitterionic, anion coordi-nated, complexes. The relative rates at which hydrogenation and then decomposition of –alkane complexes proceed are shown to be anion dependent. [BArCF34]– promotes fast hydrogenation and an indefinitely stable –alkane complex. With [BArH4]– hydrogenation is slow and the –alkane complex so unstable it is not observed. [BArCl4]– and [BArF4]– promote intermediate reactivity profiles, and for [BArCl4]– a single–crystal to single–crystal hydrogenation results in [1-NBA][BArCl4]. The molecular structure derived from X-ray diffraction reveals a –alkane complex in which the NBA fragment is bound through two exo Rh···H–C interactions – different from the endo selective binding observed with [1-NBA][BArCF34]. Periodic DFT calculations demonstrate that this selectivity is driven by the microenvironment dictated by the surrounding anions. [1-NBA][BArX4] are catalysts for gas/solid 1–butene isomerization (298 K, 1 atm) and their activity can be directly correlated to the stability of the –alkane complex compared to the anion–coordinated decomposition products. |
| first_indexed | 2024-03-07T06:02:00Z |
| format | Journal article |
| id | oxford-uuid:ec817a84-5da1-46f0-95b8-20d9257ff913 |
| institution | University of Oxford |
| last_indexed | 2024-03-07T06:02:00Z |
| publishDate | 2018 |
| publisher | American Chemical Society |
| record_format | dspace |
| spelling | oxford-uuid:ec817a84-5da1-46f0-95b8-20d9257ff9132022-03-27T11:18:11ZControlling structure and reactivity in cationic Solid–State Molecular OrganoMetallic (SMOM) systems using anion templatingJournal articlehttp://purl.org/coar/resource_type/c_dcae04bcuuid:ec817a84-5da1-46f0-95b8-20d9257ff913Symplectic Elements at OxfordAmerican Chemical Society2018McKay, AMartinez-Martinez, AGriffiths, HRees, NWaters, JWeller, AKrämer, TMacgregor, SThe role that the supporting anion has on the stability, structure and catalytic performance, in Solid-state Molecular Organ-oMetallic systems (SMOM) based upon [Rh(Cy2PCH2CH2PCy2)(η2η2-NBD)][BArX4], [1-NBD][BArX4], is reported (X = Cl, F, H; NBD = norbornadiene). The tetra–aryl borate anion is systematically varied at the 3,5–position, ArX= 3,5-X2C6H3, and the stability and structure in the solid–state compared with the previously reported [1-NBD][BArCF34] complex. Single crystal X-ray crystallography shows that the three complexes have different packing motifs, in which the cation sits on the shared face of two parallelepipeds for [1-NBD][BArCl4], is surrounded by eight anions in gyrobifastigium arrangement for [1-NBD][BArF4], or the six anions show an octahedral cage arrangement in [1-NBD][BArH4], similar to [1-NBD][BArCF34]. C-X···X-C contacts, commonly encountered in crystal–engineering, are suggested to be important in determining structure. Addition of H2 in a solid/gas reaction affords the resulting –alkane complexes, [Rh(Cy2PCH2CH2PCy2)(η2η2-NBA)][BArX4] [1-NBA][BArX4] (NBA = norbornane), which can then proceed to lose the alkane and form the zwitterionic, anion coordi-nated, complexes. The relative rates at which hydrogenation and then decomposition of –alkane complexes proceed are shown to be anion dependent. [BArCF34]– promotes fast hydrogenation and an indefinitely stable –alkane complex. With [BArH4]– hydrogenation is slow and the –alkane complex so unstable it is not observed. [BArCl4]– and [BArF4]– promote intermediate reactivity profiles, and for [BArCl4]– a single–crystal to single–crystal hydrogenation results in [1-NBA][BArCl4]. The molecular structure derived from X-ray diffraction reveals a –alkane complex in which the NBA fragment is bound through two exo Rh···H–C interactions – different from the endo selective binding observed with [1-NBA][BArCF34]. Periodic DFT calculations demonstrate that this selectivity is driven by the microenvironment dictated by the surrounding anions. [1-NBA][BArX4] are catalysts for gas/solid 1–butene isomerization (298 K, 1 atm) and their activity can be directly correlated to the stability of the –alkane complex compared to the anion–coordinated decomposition products. |
| spellingShingle | McKay, A Martinez-Martinez, A Griffiths, H Rees, N Waters, J Weller, A Krämer, T Macgregor, S Controlling structure and reactivity in cationic Solid–State Molecular OrganoMetallic (SMOM) systems using anion templating |
| title | Controlling structure and reactivity in cationic Solid–State Molecular OrganoMetallic (SMOM) systems using anion templating |
| title_full | Controlling structure and reactivity in cationic Solid–State Molecular OrganoMetallic (SMOM) systems using anion templating |
| title_fullStr | Controlling structure and reactivity in cationic Solid–State Molecular OrganoMetallic (SMOM) systems using anion templating |
| title_full_unstemmed | Controlling structure and reactivity in cationic Solid–State Molecular OrganoMetallic (SMOM) systems using anion templating |
| title_short | Controlling structure and reactivity in cationic Solid–State Molecular OrganoMetallic (SMOM) systems using anion templating |
| title_sort | controlling structure and reactivity in cationic solid state molecular organometallic smom systems using anion templating |
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