Reversible Binding of Dihydrogen in Multimetallic Complexes

Abstract

The interaction of hydrogen with metal surfaces is one of the most important and fundamental processes in the chemical industry. Hydrogen is also strongly tipped to play a central role in new challenges that are emerging in terms of climate change and energy supply, and the reversible binding of H 2 to suitable materials will play a keystone role in the realisation of the hydrogen economy. The reversible interaction of hydrogen with multimetallic centres is also an important theme in biological processes; the role of hydrogenases in the metabolism of H 2 is an example. Thus the reversible interaction of H 2 with multimetallic metal complexes is an area that spans considerable breadth. This review is concerned

Synthesis, Spectroscopy, and Hydrogen/Deuterium Exchange in High-Spin Iron(II) Hydride Complexes

“…16 It is well-established in mononuclear iron-hydride complexes. 34 In each of these cases, an open coordination site is required to bind H 2 in an η 2 binding mode.…”

Formation and Characterisation of the Silver Hydride Nanocluster Cation [Ag3H2((Ph2P)2CH2)]+ and Its Release of Hydrogen

“…The widespread use of hydrogen is hampered due to the challenge of safely storing and transporting it in its natural gaseous state 1. 2 Notwithstanding the issue of H % weight content,3 metal hydrides have long attracted attention as a storage medium for hydrogen, which can subsequently be released by heating or via irradiation with light 4…”

“…[1,2] Notwithstanding the issue of H % weight content, [3] metal hydrides have long attracted attention as a storage medium for hydrogen, which can subsequently be released by heating or via irradiation with light. [4] Silver hydrides are key intermediates in a number of reactions involving organic substrates [5] and several silver hydrides have been recently isolated and structurally characterised by X-ray crystallography. [6] In one such study, hydrogen evolution from [(LAg) 2 H] + (where L = N-heterocyclic carbene ligand 1,3bis(2,6-diisopropylphenyl)imidazolin-2-ylidene) was observed, but the precise mechanism for H 2 formation is unknown.…”

Proton‐Transfer Reactions on Hexanuclear Platinum Clusters: Reversible Heterolytic Cleavage of H2 and CH Activation Affording a Linear, Cluster‐Containing Polymer

“…Finally, it may be interesting to note that, whereas the above-mentioned remarkable examples of hindered molecular clusters, kinetically stabilised by bulky phosphines, de- scribed by Weller [15,17] and Adams [18] are able to oxidatively add (reversibly) a large number of H 2 molecules, our {Pt 6 }A 2 clusters activate the H À H bond and the C À H bond of DME by heterolytic splitting. The extension of this procedure to other ethers and to other CÀH bonds, and the possible applications to homogeneous catalysis [19e, 30] are currently under investigation.…”

“…Moreover, it must be remembered that thermally unstable dihydrogen complexes, with two bulky phosphorus ligands cis to the Pt(H 2 ) site, have been observed previously and characterised in detail in squareplanar mononuclear platinum(II) complexes, [8a, 14] but nonclassical bonding of dihydrogen in molecular clusters of transition metals has been suggested rarely and only on the basis of indirect evidence. [15] Trapping one or more kinetic intermediate (and the nature of the trapped species) in the complex pathway from 2 to 4 may depend strongly on various parameters, especially on the solvent and on the acid strength of HA. Unfortunately, as mentioned above, following the reaction with TfOH at low temperatures in apolar solvents turned out to be impossible and, therefore, we decided to investigate the (slower) reaction with weaker acids.…”