Ligand Lability Driven by Metal-to-Borane Pseudorotation: A Mechanism for Ligand Exchange

Abstract

The discovery of systems that interact with small molecules plays a vital facilitating role in the development of devices that show sensitivity to their surroundings and an ability to quickly relay chemical and physical information. Herein, we report on the reaction of [NiCl 2 (dppe)] with decaborane that produces in usable yield a new 11-vertex nickelaborane, [7,7-(dppe)-nido-7-NiB 10 H 12 ] (1), which shows interesting reactivity and functionality toward carbon monoxide and ethylisonitrile. This contribution describes the synthesis and full structural characterization of 1 and its smallmolecule EtNC and CO adducts, 2 and 3, and delineates the dynamic molecular behavior of all of these species in solution. This information sets a foundation from which more advanced work on this and related metallaborane systems can be conceived and provides a more general reference to how NMR spectroscopy, combined with DFT calculations, can be used to analyze the precise locomotion of labile ligands around a metal center held within a borane cluster.

A simple and high-yield route to iridium, rhodium, osmium and rutheniumnido-6-metalladecaborane compounds

“…[56][57][58][59][60][61][62][63] We have recently reported that metal-to-borane rotation can have an effect on the lability of the metal-bound exo-polyhedral ligands, and hence the opening of coordination sites for ligand substitutions. 64 The isomerization of the metal exo-ligand symmetric conformer in ortho-cyclometallated [6-H-6-(PPh 3 )--6 P ,5 C -(PPh 2 -ortho-C 6 H 4 )nido-6-IrB 9 H 12 ] to its asymmetric isomer, 65 suggests that rotation of the metal vertex with respect to the { 3 -B 9 H 13 } fragment in 1, 2, 3 and 4 is a feature worthy of study. We therefore modelled the rotation of the exo-polyhedral ligand sphere by performing a DFT-calculated relaxed Potential Energy Surface (PES) scan of the system, in which the PPh 3 ligands are replaced by PH 3 in order to save computational time.…”

Dynamic metal-linker bonds in metal–organic frameworks

“…1–3 While enthalpy favours ML bond formation, entropy drives their dissociation such that all ML bonds exist to varying degrees in dynamic equilibria between bound and unbound states. This bond lability impacts the mechanisms of transition metal catalysis 4–6 and enables the self-healing behaviour observed in coordination polymers. 7–10 Among traditional solid-state materials, the earliest examples of ferroelectric phase-change behaviour were documented to involve a special class of ML phonons, 11–13 now termed soft modes.…”

Dynamic metal-linker bonds in metal-organic frameworks

“…[1][2][3] While enthalpy favours ML bond formation, entropy drives their dissociation such that all ML bonds exist to varying degrees in dynamic equilibria between bound and unbound states. This bond lability impacts the mechanisms of transition metal catalysis [4][5][6] and enables the self-healing behaviour observed in coordination polymers. [7][8][9][10] Among traditional solid-state materials, the earliest examples of ferroelectric phase-change behaviour were documented to involve a special class of ML phonons, [11][12][13] now termed soft modes.…”