Stoichiometric and catalytic solid-gas reactivity of rhodium bis-phosphine complexes

Sebastian D. Pike; Tobias Kraemer; Nicholas H. Rees; Stuart A. Macgregor; Andrew S. Weller

doi:10.1021/om5013133

Stoichiometric and catalytic solid-gas reactivity of rhodium bis-phosphine complexes

Sebastian D. Pike, Tobias Kraemer, Nicholas H. Rees, Stuart A. Macgregor^*, Andrew S. Weller

^*Corresponding author for this work

Research output: Contribution to journal › Article › peer-review

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Abstract

The complexes [Rh(iBu<inf>2</inf>PCH<inf>2</inf>CH<inf>2</inf>PiBu<inf>2</inf>)L<inf>2</inf>][BArF<inf>4</inf>] [L<inf>2</inf> = C<inf>4</inf>H<inf>6</inf>, (C<inf>2</inf>H<inf>4</inf>)<inf>2</inf>, (CO)<inf>2</inf>, (NH<inf>3</inf>)<inf>2</inf>; ArF = 3,5-C<inf>6</inf>H<inf>3</inf>(CF<inf>3</inf>)<inf>2</inf>] have been synthesized by solid-gas reactivity via ligand exchange reactions with, in some cases, crystallinity retained through single-crystal to single-crystal transformations. The solid-state structures of these complexes have been determined, but in only one case (L<inf>2</inf> = (NH<inf>3</inf>)<inf>2</inf>) is the cation ordered sufficiently to enable its structural metrics to be determined by single crystal X-ray diffraction. The onward solid-state reactivity of some of these complexes has been probed. The bis-ammonia complex [Rh(iBu<inf>2</inf>PCH<inf>2</inf>CH<inf>2</inf>PiBu<inf>2</inf>)(NH<inf>3</inf>)<inf>2</inf>][BArF<inf>4</inf>] undergoes H/D exchange at bound NH<inf>3</inf> when exposed to D<inf>2</inf>. The bis-ethene complex [Rh(iBu<inf>2</inf>PCH<inf>2</inf>CH<inf>2</inf>PiBu<inf>2</inf>)(C<inf>2</inf>H<inf>4</inf>)<inf>2</inf>][BArF<inf>4</inf>] undergoes a slow dehydrogenative coupling reaction to produce a material containing a 1:1 mixture of the butadiene complex and a postulated mono-ethene complex. The mechanisms of these processes have been probed by DFT calculations on the isolated Rh cations. All the solid materials were tested as heterogeneous catalysts for the hydrogenation of ethene. Complexes with weakly bound ligands (e.g., L<inf>2</inf> = (C<inf>2</inf>H<inf>4</inf>)<inf>2</inf>) are more active catalysts than those with stronger bound ligands (e.g., L = (CO)<inf>2</inf>). Surface-passivated crystals, formed through partial reaction with CO, allow for active sites to be probed, either on the surface or the interior of the single crystal.

Original language	English
Pages (from-to)	1487-1497
Number of pages	11
Journal	Organometallics
Volume	34
Issue number	8
Early online date	9 Mar 2015
DOIs	https://doi.org/10.1021/om5013133
Publication status	Published - 27 Apr 2015

ASJC Scopus subject areas

Organic Chemistry
Physical and Theoretical Chemistry
Inorganic Chemistry

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@article{3b218c33c585464f9bb772b92ffc16b9,

title = "Stoichiometric and catalytic solid-gas reactivity of rhodium bis-phosphine complexes",

abstract = "The complexes [Rh(iBu2PCH2CH2PiBu2)L2][BArF4] [L2 = C4H6, (C2H4)2, (CO)2, (NH3)2; ArF = 3,5-C6H3(CF3)2] have been synthesized by solid-gas reactivity via ligand exchange reactions with, in some cases, crystallinity retained through single-crystal to single-crystal transformations. The solid-state structures of these complexes have been determined, but in only one case (L2 = (NH3)2) is the cation ordered sufficiently to enable its structural metrics to be determined by single crystal X-ray diffraction. The onward solid-state reactivity of some of these complexes has been probed. The bis-ammonia complex [Rh(iBu2PCH2CH2PiBu2)(NH3)2][BArF4] undergoes H/D exchange at bound NH3 when exposed to D2. The bis-ethene complex [Rh(iBu2PCH2CH2PiBu2)(C2H4)2][BArF4] undergoes a slow dehydrogenative coupling reaction to produce a material containing a 1:1 mixture of the butadiene complex and a postulated mono-ethene complex. The mechanisms of these processes have been probed by DFT calculations on the isolated Rh cations. All the solid materials were tested as heterogeneous catalysts for the hydrogenation of ethene. Complexes with weakly bound ligands (e.g., L2 = (C2H4)2) are more active catalysts than those with stronger bound ligands (e.g., L = (CO)2). Surface-passivated crystals, formed through partial reaction with CO, allow for active sites to be probed, either on the surface or the interior of the single crystal.",

author = "Pike, {Sebastian D.} and Tobias Kraemer and Rees, {Nicholas H.} and Macgregor, {Stuart A.} and Weller, {Andrew S.}",

year = "2015",

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doi = "10.1021/om5013133",

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pages = "1487--1497",

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TY - JOUR

T1 - Stoichiometric and catalytic solid-gas reactivity of rhodium bis-phosphine complexes

AU - Pike, Sebastian D.

AU - Kraemer, Tobias

AU - Rees, Nicholas H.

AU - Macgregor, Stuart A.

AU - Weller, Andrew S.

PY - 2015/4/27

Y1 - 2015/4/27

N2 - The complexes [Rh(iBu2PCH2CH2PiBu2)L2][BArF4] [L2 = C4H6, (C2H4)2, (CO)2, (NH3)2; ArF = 3,5-C6H3(CF3)2] have been synthesized by solid-gas reactivity via ligand exchange reactions with, in some cases, crystallinity retained through single-crystal to single-crystal transformations. The solid-state structures of these complexes have been determined, but in only one case (L2 = (NH3)2) is the cation ordered sufficiently to enable its structural metrics to be determined by single crystal X-ray diffraction. The onward solid-state reactivity of some of these complexes has been probed. The bis-ammonia complex [Rh(iBu2PCH2CH2PiBu2)(NH3)2][BArF4] undergoes H/D exchange at bound NH3 when exposed to D2. The bis-ethene complex [Rh(iBu2PCH2CH2PiBu2)(C2H4)2][BArF4] undergoes a slow dehydrogenative coupling reaction to produce a material containing a 1:1 mixture of the butadiene complex and a postulated mono-ethene complex. The mechanisms of these processes have been probed by DFT calculations on the isolated Rh cations. All the solid materials were tested as heterogeneous catalysts for the hydrogenation of ethene. Complexes with weakly bound ligands (e.g., L2 = (C2H4)2) are more active catalysts than those with stronger bound ligands (e.g., L = (CO)2). Surface-passivated crystals, formed through partial reaction with CO, allow for active sites to be probed, either on the surface or the interior of the single crystal.

AB - The complexes [Rh(iBu2PCH2CH2PiBu2)L2][BArF4] [L2 = C4H6, (C2H4)2, (CO)2, (NH3)2; ArF = 3,5-C6H3(CF3)2] have been synthesized by solid-gas reactivity via ligand exchange reactions with, in some cases, crystallinity retained through single-crystal to single-crystal transformations. The solid-state structures of these complexes have been determined, but in only one case (L2 = (NH3)2) is the cation ordered sufficiently to enable its structural metrics to be determined by single crystal X-ray diffraction. The onward solid-state reactivity of some of these complexes has been probed. The bis-ammonia complex [Rh(iBu2PCH2CH2PiBu2)(NH3)2][BArF4] undergoes H/D exchange at bound NH3 when exposed to D2. The bis-ethene complex [Rh(iBu2PCH2CH2PiBu2)(C2H4)2][BArF4] undergoes a slow dehydrogenative coupling reaction to produce a material containing a 1:1 mixture of the butadiene complex and a postulated mono-ethene complex. The mechanisms of these processes have been probed by DFT calculations on the isolated Rh cations. All the solid materials were tested as heterogeneous catalysts for the hydrogenation of ethene. Complexes with weakly bound ligands (e.g., L2 = (C2H4)2) are more active catalysts than those with stronger bound ligands (e.g., L = (CO)2). Surface-passivated crystals, formed through partial reaction with CO, allow for active sites to be probed, either on the surface or the interior of the single crystal.

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U2 - 10.1021/om5013133

DO - 10.1021/om5013133

M3 - Article

SN - 0276-7333

VL - 34

SP - 1487

EP - 1497

JO - Organometallics

JF - Organometallics

IS - 8

ER -

Stoichiometric and catalytic solid-gas reactivity of rhodium bis-phosphine complexes

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