Three-centre dihydrogen bond with fast interchange between proton and hydride: a very active catalyst for D+–H2 exchange†

The Chemistry of New Nitrosyltungsten Complexes with Pyridyl-Functionalized Phosphane Ligands

“…The insertion of carbon dioxide into the metal hydride bond yielding the formato complex 26 was achieved by slowly bubbling a stream of CO 2 gas through a solution of 10 in THF [Equation (10)]. …”

“…[9] The pyridylphosphane ligand offers the possibility of either abstracting a proton from an external source or of activating a dihydrogen ligand coordinated to an unsaturated metal centre. [10] Therefore, this base-promoted splitting of dihydrogen through formation of a (ligandϪH ϩ )Ϫ(metalϪH Ϫ ) intermediate is of great significance with regard to catalytic ionic hydrogenations, as recently described by Noyori. [11,12] In order to design such a bifunctional system, we set out to prepare a series of cationic nitrosyltungsten and nitrosyltungsten hydride species having basic pyridyl substituents present in their coordinatrans-HW(CO) 2 (NO)(Ph 2 Ppy) 2 (10), trans,trans-HW(CO) 2 (N-O)(Ph 2 Ppic) 2 (12), trans,trans-HW(CO) 2 (NO)(Ph 2 -tBupy) 2 (15), cis/trans-HW(CO) 2 (NO)(Me 2 Ppy) 2 (17), and cis/trans-HW(CO) 2 (NO)(Me 2 P-tert-Bupy) 2 (19), respectively.…”

“…[10] Therefore, this base-promoted splitting of dihydrogen through formation of a (ligandϪH ϩ )Ϫ(metalϪH Ϫ ) intermediate is of great significance with regard to catalytic ionic hydrogenations, as recently described by Noyori. [11,12] In order to design such a bifunctional system, we set out to prepare a series of cationic nitrosyltungsten and nitrosyltungsten hydride species having basic pyridyl substituents present in their coordinatrans-HW(CO) 2 (NO)(Ph 2 Ppy) 2 (10), trans,trans-HW(CO) 2 (N-O)(Ph 2 Ppic) 2 (12), trans,trans-HW(CO) 2 (NO)(Ph 2 -tBupy) 2 (15), cis/trans-HW(CO) 2 (NO)(Me 2 Ppy) 2 (17), and cis/trans-HW(CO) 2 (NO)(Me 2 P-tert-Bupy) 2 (19), respectively. Reactivity experiments with acetic acid, hydroiodic acid, carbon dioxide, and acetylenedicarboxylic acid were performed, and were found to afford trans-W(CO)(NO)(Ph 2 Ppy) 2 (η 2 -CH 3 CO 2 ) (24), trans,trans-IW(CO) 2 (NO)(Ph 2 Ppy) 2 (25), trans-W(HCO 2 )(CO) 2 (NO)(Ph 2 Ppy) 2 (26), and trans-W{η 2 -(Z)-C(CO 2 Me)=CH[C(O)OMe]}(CO)(NO)(Ph 2 Ppic) 2 (27), respectively.…”

A theoretical study of three and four proton donors on linear HX···BeH2···HX and bifurcate BeH2···2HX trimolecular dihydrogen-bonded complexes with X = CN and NC

“…According to Jalón and co-workers [31], the ''electronegative'' capacity of H -d in BeH 2 was demonstrated in a theoretical description of the trimolecular dihydrogenbonded complex BeH 2 ÁÁÁ2HCl [32], but now, our idea is concentrated in a computational study elaborated to verify whether HCN and HNC are able acids to form trimolecular dihydrogen-bonded complexes not only by evaluating the terminal (1) hydride of BeH 2 (BeH 2 ÁÁÁ2HCN and BeH 2 ÁÁÁ2HNC) as proton acceptor center, but also two (2) hydrides simultaneously (NCHÁÁÁBeH 2 ÁÁÁHCN and CNHÁÁÁBeH 2 ÁÁÁHNC), as illustrated in Scheme 1. Thus, a natural question arises: how can we show that these dihydrogen-bonded complexes are formed in a minimum potential energy surface?…”

Hydridic reactivity of W(CO)(H)(NO)(PMe3)3 – Dihydrogen bonding and H2 formation with protic donors

“…In conjunction with catalysis, such as ''ionic hydrogenations" proceeding with proton and hydride transfers [32][33][34][35][36][37], the significance of particularly dihydrogen bonding is still a matter of dispute. Intramolecular hydrogen bonding of the hydride ligand was first discovered in the solid state in the groups of Morris and Crabtree [9][10][11], while the groups of Shubina and Berke provided spectroscopic, thermodynamic and structural evidence for intermolecular MHÁÁÁHX bonding in solution [12][13][14][15][16].…”