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

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 1, 4, 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]+.

Study the Chemical Bonding of Heterometallic Trinuclear Cluster Containing Cobalt and Ruthenium: [(Cp*Co) (CpRu)2 (μ3-H) (μ-H)3] using QTAIM Approach

“…Finally, the calculated ellipticities for the M-C bonds showed that the ellipticities average values of Co-Cp* interactions 1.317 are in most cases higher than the Ru-Cp bonds (ranging from 0.647-0.992). Large calculated values for the ellipticities indicated that the M-C bonds have a л character and are consistent with earlier research based on the MO theory 41 . Delocalization Indices.…”

A Theoretical Investigation of Chemical Bonding of a Heterometallic Trinuclear Cluster Containing Iridium and Ruthenium: [(Cp*Ir) (CpRu)2 (μ3-H) (μ-H)3] by QTAIM Approach

“…-Cp* interactions (1.561) are in most cases lower than the Ru-Cp bonds (1.258-2.031). The M-C bonds have a л character, according to computed large values for the ellipticities, which is compatible with past findings based on the MO theory43 .…”

“…These numbers are consistent with the values that have previously been published in the literature 42 . Finally, the calculated ellipticities for the M-C bonds showed that the ellipticities average The delocalization index, δ(A, B), is one of the best tools to estimate the number of delocalized electron pairs between two atoms 43,44 . Therefore, as listed in Table 2, we calculated these indices as a tool to analyze a multicenter bonding in this cluster from one side and to describe different M…M interaction modes from another side 38 .…”

Photochemical H2 activation by an Zn–Fe heterometallic: a mechanistic investigation

“…To the best of our knowledge, photolytic reactivity is limited to two examples involving the addition of H 2 to Ru-Zn and Ru-Al heterometallic complexes. 11,12 These ndings contrast the rich chemistry of single-site transition metal complexes, where examples of photochemical H 2 activation are more common. Under photolytic conditions, 18-electron transition metal carbonyl complexes are prone to ligand dissociation to generate coordinatively unsaturated intermediates that can react with H 2 .…”

“…To the best of our knowledge, photolytic reactivity is limited to two examples involving the addition of H 2 to Ru–Zn and Ru–Al heterometallic complexes. 11,12…”