Hydrogen atom storage upon Z-class borane ligand functions: an alternative approach to ligand cooperation

Abstract

Ligand cooperation has become an important strategy in the development of new transition metal based transformations. By using this approach some remarkable new catalytic transformations have been achieved, all in the space of only a few years. The purpose of this tutorial review is to explore the potential utilisation of ligands containing borohydride and borane functionalities as reversible hydrogen atom stores. At the heart of this review will be a discussion on hydrogen transfer reactions and the transformation between borohydride and borane moieties. An outline of the various synthetic routes to metal-borane (metallaboratrane) complexes will be provided together with a discussion of their further reactivity including key transformations such as 1,2 additions across the metal-boron bond and 'recharging' the borane functional group back to borohydride. Finally, an evaluation of the potential future applications of such reactivity will be provided.

Synthesis, characterization and catalytic activity of gold complexes with pyridine-based selone ligands

“…Reports about transition metal complexes with imidazoline-2-chalcogenone ligands have been reported within past few years [44][45][46][47][48][49]. And the catalytic activities of these complexes are comparable with the most efficient metal-NHC complexes for organic transformation [50][51][52].…”

Reactivity of [M2(μ‐Cl)2(cod)2] (M=Ir, Rh) and [Ru(Cl)2(cod)(CH3CN)2] with Na[H2B(bt)2]: Formation of Agostic versus Borate Complexes

“…[D 6 ]Benzene and [D 8 ]toluene were dried over sodium metal. The 1 H, 13 C, and 11 BNMR spectra were recorded on aB ruker 400 and 500 MHz instruments. The external reference for the 11 BNMR spectroscopy, [Bu 4 N(B 3 H 8 )] was synthesized according to the reported method.…”

“…Furthermore, we report the synthesis and X-ray structureso ft he metal analogues of 1,5-cyclooctadiene [(Mcod) 2 (bt) 2 ] 1 and 2 (1:M= Ir; 2:M= Rh). 13 CNMR spectra show the existence of typical peaks associated with cod and the 2-mercaptobenzothiazolyl ligands. The solid-stateX -ray structure analyses of 1 and 2 (Figure 1) show the presence of an eight-membered dimetallahetero bicyclic ring, [(h 4 -COD)MSC=NM(h 4 -COD)SC=N]( M = Ir and Rh) in which the metals are in ap seudoo ctahedral arrangement.…”

“…have observed a reversible transformation between borylene and bis(σ‐borane) functionalities via reversible hydrogen release . Apart from the structural aspects of these ligands, these metal borane complexes have been utilized in catalysis and hydrogenation of olefins …”

“…[11] Apart from the structural aspectso ft hese ligands, [12] these metal borane complexesh ave been utilized in catalysis and hydrogenation of olefins. [13,14] As part of our currenti nteresti nt he synthesis of electronprecise transition-metal boron complexes, we have recently reported an umber of agostic s-borane/borate complexes of ruthenium, rhodium,i ridium,a nd molybdenum using different synthetic approaches. [15,16] For example, the reaction of [(Cp*Ru) 2 B 3 H 9 ]( Cp* = h 5 -C 5 Me 5 )w ith 2-mbz (2-mercapto-benzothiazole) yielded bis(s)borate[ Cp*RuBH 3 (L)],a nd agostic complexes[ Cp*RuBH 2 (L) 2 ]( L = C 7 H 4 NS).…”