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 M. Miloserdov, Mary F. Mahon, Stuart A. Macgregor, Michael K. Whittlesey

Research output: Contribution to journalArticlepeer-review

4 Citations (Scopus)
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Abstract

Reaction of [Ru(C6H4PPh2)2(Ph2PC6H4AlMe(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-Ph2PC6H4)2AlMe. Under photolytic conditions, 1 reacts with H2 to 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 H2 addition to 1 and predict facile hydride exchange in 2 that is also observed experimentally. Reaction of 1 with B(C6F5)3 results in Me abstraction to form the ion pair [Ru(AlPhos)(CO)3][MeB(C6F5)3] (4) featuring a cationic [(o-Ph2PC6H4)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 νCO stretching frequencies upon Me abstraction. Electronic structure analyses (QTAIM and EDA-ETS) comparing 14, and the previously reported [Ru(ZnPhos)(CO)3] analogue (ZnPhos = (o-Ph2PC6H4)2Zn) indicate that the Lewis acidity of these pincer ligands increases along the series ZnPhos < AlMePhos < [AlPhos]+.

Original languageEnglish
Pages (from-to)20690-20698
Number of pages9
JournalInorganic Chemistry
Volume61
Issue number50
Early online date7 Dec 2022
DOIs
Publication statusPublished - 19 Dec 2022

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