Experimental and Computational Studies of Ruthenium Complexes Bearing Z-Acceptor Aluminum-Based Phosphine Pincer Ligands

Connie J. Isaac; Cameron I. Wilson; Arron L. Burnage; Fedor Miloserdov; Mary F. Mahon; Stuart A. Macgregor; Michael K. Whittlesey

doi:10.1021/acs.inorgchem.2c03665

Experimental and Computational Studies of Ruthenium Complexes Bearing Z-Acceptor Aluminum-Based Phosphine Pincer Ligands

Connie J. Isaac, Cameron I. Wilson, Arron L. Burnage, Fedor Miloserdov, Mary F. Mahon, Stuart A. Macgregor, Michael K. Whittlesey

Department of Chemistry

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Abstract

Reaction of [Ru(C ₆H ₄PPh ₂) ₂(Ph ₂PC ₆H ₄AlMe(THF))H] with CO results in clean conversion to the Ru-Al heterobimetallic complex [Ru(AlMePhos)(CO) ₃] (1), where AlMePhos is the novel P-Al(Me)-P pincer ligand (o-Ph ₂PC ₆H ₄) ₂AlMe. Under photolytic conditions, 1 reacts with H ₂to give [Ru(AlMePhos)(CO) ₂(μ-H)H] (2) that is characterized by multinuclear NMR and IR spectroscopies. DFT calculations indicate that 2 features one terminal and one bridging hydride that are respectively anti and syn to the AlMe group. Calculations also define a mechanism for H ₂addition to 1 and predict facile hydride exchange in 2 that is also observed experimentally. Reaction of 1 with B(C ₆F ₅) ₃results in Me abstraction to form the ion pair [Ru(AlPhos)(CO) ₃][MeB(C ₆F ₅) ₃] (4) featuring a cationic [(o-Ph ₂PC ₆H ₄) ₂Al] ⁺ligand, [AlPhos] ⁺. The Ru-Al distance in 4 (2.5334(16) Å) is significantly shorter than that in 1 (2.6578(6) Å), consistent with an enhanced Lewis acidity of the [AlPhos] ⁺ligand. This is corroborated by a blue shift in both the observed and computed ν _COstretching frequencies upon Me abstraction. Electronic structure analyses (QTAIM and EDA-ETS) comparing 1, 4, and the previously reported [Ru(ZnPhos)(CO) ₃] analogue (ZnPhos = (o-Ph ₂PC ₆H ₄) ₂Zn) indicate that the Lewis acidity of these pincer ligands increases along the series ZnPhos < AlMePhos < [AlPhos] ⁺. copy; 2022 American Chemical Society.

Original language	English
Pages (from-to)	20690-20698
Number of pages	9
Journal	Inorganic Chemistry
Volume	61
Issue number	50
Early online date	7 Dec 2022
DOIs	https://doi.org/10.1021/acs.inorgchem.2c03665
Publication status	Published - 19 Dec 2022

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@article{39289a88414a418f9d2ae4c18fc1fb74,

title = "Experimental and Computational Studies of Ruthenium Complexes Bearing Z-Acceptor Aluminum-Based Phosphine Pincer Ligands",

abstract = "Reaction of [Ru(C 6H 4PPh 2) 2(Ph 2PC 6H 4AlMe(THF))H] with CO results in clean conversion to the Ru-Al heterobimetallic complex [Ru(AlMePhos)(CO) 3] (1), where AlMePhos is the novel P-Al(Me)-P pincer ligand (o-Ph 2PC 6H 4) 2AlMe. Under photolytic conditions, 1 reacts with H 2to give [Ru(AlMePhos)(CO) 2(μ-H)H] (2) that is characterized by multinuclear NMR and IR spectroscopies. DFT calculations indicate that 2 features one terminal and one bridging hydride that are respectively anti and syn to the AlMe group. Calculations also define a mechanism for H 2addition to 1 and predict facile hydride exchange in 2 that is also observed experimentally. Reaction of 1 with B(C 6F 5) 3results in Me abstraction to form the ion pair [Ru(AlPhos)(CO) 3][MeB(C 6F 5) 3] (4) featuring a cationic [(o-Ph 2PC 6H 4) 2Al] +ligand, [AlPhos] +. The Ru-Al distance in 4 (2.5334(16) {\AA}) is significantly shorter than that in 1 (2.6578(6) {\AA}), consistent with an enhanced Lewis acidity of the [AlPhos] +ligand. This is corroborated by a blue shift in both the observed and computed ν COstretching frequencies upon Me abstraction. Electronic structure analyses (QTAIM and EDA-ETS) comparing 1, 4, and the previously reported [Ru(ZnPhos)(CO) 3] analogue (ZnPhos = (o-Ph 2PC 6H 4) 2Zn) indicate that the Lewis acidity of these pincer ligands increases along the series ZnPhos < AlMePhos < [AlPhos] +. copy; 2022 American Chemical Society.",

author = "Isaac, {Connie J.} and Wilson, {Cameron I.} and Burnage, {Arron L.} and Fedor Miloserdov and Mahon, {Mary F.} and Macgregor, {Stuart A.} and Whittlesey, {Michael K.}",

note = "Funding Information: This project has received funding from the European Union{\textquoteright}s Horizon 2020 research and innovation programme under the Marie Sk{\l}odowska-Curie grant agreement no. 792674 (FMM) and EPSRC (DTP studentships to C.J.I. and A.L.B.). We thank Dr. John Lowe for NMR assistance, Dr. Ulrich Hintermair and Dr. Ruth Webster for access to their ATR-IR and ReactIR systems, respectively, and Dr. Tom Hood for the help with the ReactIR experiments. Publisher Copyright: {\textcopyright} 2022 American Chemical Society. All rights reserved.",

year = "2022",

month = dec,

day = "19",

doi = "10.1021/acs.inorgchem.2c03665",

language = "English",

volume = "61",

pages = "20690--20698",

journal = "Inorganic Chemistry",

issn = "0020-1669",

publisher = "American Chemical Society",

number = "50",

}

TY - JOUR

T1 - Experimental and Computational Studies of Ruthenium Complexes Bearing Z-Acceptor Aluminum-Based Phosphine Pincer Ligands

AU - Isaac, Connie J.

AU - Wilson, Cameron I.

AU - Burnage, Arron L.

AU - Miloserdov, Fedor

AU - Mahon, Mary F.

AU - Macgregor, Stuart A.

AU - Whittlesey, Michael K.

N1 - Funding Information: This project has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement no. 792674 (FMM) and EPSRC (DTP studentships to C.J.I. and A.L.B.). We thank Dr. John Lowe for NMR assistance, Dr. Ulrich Hintermair and Dr. Ruth Webster for access to their ATR-IR and ReactIR systems, respectively, and Dr. Tom Hood for the help with the ReactIR experiments. Publisher Copyright: © 2022 American Chemical Society. All rights reserved.

PY - 2022/12/19

Y1 - 2022/12/19

N2 - Reaction of [Ru(C 6H 4PPh 2) 2(Ph 2PC 6H 4AlMe(THF))H] with CO results in clean conversion to the Ru-Al heterobimetallic complex [Ru(AlMePhos)(CO) 3] (1), where AlMePhos is the novel P-Al(Me)-P pincer ligand (o-Ph 2PC 6H 4) 2AlMe. Under photolytic conditions, 1 reacts with H 2to give [Ru(AlMePhos)(CO) 2(μ-H)H] (2) that is characterized by multinuclear NMR and IR spectroscopies. DFT calculations indicate that 2 features one terminal and one bridging hydride that are respectively anti and syn to the AlMe group. Calculations also define a mechanism for H 2addition to 1 and predict facile hydride exchange in 2 that is also observed experimentally. Reaction of 1 with B(C 6F 5) 3results in Me abstraction to form the ion pair [Ru(AlPhos)(CO) 3][MeB(C 6F 5) 3] (4) featuring a cationic [(o-Ph 2PC 6H 4) 2Al] +ligand, [AlPhos] +. The Ru-Al distance in 4 (2.5334(16) Å) is significantly shorter than that in 1 (2.6578(6) Å), consistent with an enhanced Lewis acidity of the [AlPhos] +ligand. This is corroborated by a blue shift in both the observed and computed ν COstretching frequencies upon Me abstraction. Electronic structure analyses (QTAIM and EDA-ETS) comparing 1, 4, and the previously reported [Ru(ZnPhos)(CO) 3] analogue (ZnPhos = (o-Ph 2PC 6H 4) 2Zn) indicate that the Lewis acidity of these pincer ligands increases along the series ZnPhos < AlMePhos < [AlPhos] +. copy; 2022 American Chemical Society.

AB - Reaction of [Ru(C 6H 4PPh 2) 2(Ph 2PC 6H 4AlMe(THF))H] with CO results in clean conversion to the Ru-Al heterobimetallic complex [Ru(AlMePhos)(CO) 3] (1), where AlMePhos is the novel P-Al(Me)-P pincer ligand (o-Ph 2PC 6H 4) 2AlMe. Under photolytic conditions, 1 reacts with H 2to give [Ru(AlMePhos)(CO) 2(μ-H)H] (2) that is characterized by multinuclear NMR and IR spectroscopies. DFT calculations indicate that 2 features one terminal and one bridging hydride that are respectively anti and syn to the AlMe group. Calculations also define a mechanism for H 2addition to 1 and predict facile hydride exchange in 2 that is also observed experimentally. Reaction of 1 with B(C 6F 5) 3results in Me abstraction to form the ion pair [Ru(AlPhos)(CO) 3][MeB(C 6F 5) 3] (4) featuring a cationic [(o-Ph 2PC 6H 4) 2Al] +ligand, [AlPhos] +. The Ru-Al distance in 4 (2.5334(16) Å) is significantly shorter than that in 1 (2.6578(6) Å), consistent with an enhanced Lewis acidity of the [AlPhos] +ligand. This is corroborated by a blue shift in both the observed and computed ν COstretching frequencies upon Me abstraction. Electronic structure analyses (QTAIM and EDA-ETS) comparing 1, 4, and the previously reported [Ru(ZnPhos)(CO) 3] analogue (ZnPhos = (o-Ph 2PC 6H 4) 2Zn) indicate that the Lewis acidity of these pincer ligands increases along the series ZnPhos < AlMePhos < [AlPhos] +. copy; 2022 American Chemical Society.

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U2 - 10.1021/acs.inorgchem.2c03665

DO - 10.1021/acs.inorgchem.2c03665

M3 - Article

SN - 0020-1669

VL - 61

SP - 20690

EP - 20698

JO - Inorganic Chemistry

JF - Inorganic Chemistry

IS - 50

ER -

Experimental and Computational Studies of Ruthenium Complexes Bearing Z-Acceptor Aluminum-Based Phosphine Pincer Ligands

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