Proton-hydride interaction

It should be noted, however, that chemists had thought inmitively about proton-hydride interactions long before their formulation as dihydrogen bonds. For... 

The concept of the proton-hydride interaction or dUiydrogen bonding (DHB) was generalized by Morris ... 

From 1995, we and Morris group found a long series of metal hydrides in which a transition metal M-H bond acts as the weak base (proton acceptor) in a hydrogen bond with OH or NH protons ( = A-H) as the weak acid partners. This was shown by the short H-H distance ca. 1.8 A) and by studies that identified the A-H-H-M interaction strength as ca. 4-8 kcal moP Classical hydrogen bonds, A-H-B, require a lone pair on the base, B, and both A and B are electronegative. In A-H-H-M, the lone pair of the weak base, B, is apparently replaced by the M-H (x-bond, and both M and H are much more electropositive than the N, O or F atoms common in the classical type, so we have a new class of hydrogen bond. Morris has used an alternative descriptive term, proton-hydride interaction. 

A combination of computational and experimental approaches gives an understanding of the proton-hydride interaction. This new type of hydrogen bond, the dihydrogen bond, is shown to influence the physical properties and reactivities of a number of main group and transition metal compounds. It seems to be important in cases of protonation of hydrides by acids HA. 

In a number of recent studies, metal hydrides have been shown to act as the weak base (proton acceptor) component of a hydrogen bond. Classical hydrogen bonds [2a] of type A-H -B, show a weak electrostatic attraction between a weak acid, AH, and a weak base, B, requiring the presence of a lone pair on the base, B. Both A and B are electronegative atoms or groups. In the dihydrogen bond, A-H--H-M, the role of the weak base is taken by M-H. As Morris [2b] has noted, these interactions can also be considered as arising from an attractive interaction between a proton and a hydride hence the alternative term, proton-hydride interaction. 

Unlike classical hydrogen bonds,A-H...B, where A and B are electronegative atoms or groups, in A-H...H-M, M and H are much less electronegative than the N, O, or F atoms common in the classical type. Morris " used an alternative descriptive term proton-hydride interaction. 

A combination of computational and experimental approaches gives an understanding of the proton-hydride interaction in the This new type of hydrogen... 

A new intramolecular proton-hydride interaction was independently discovered by Crabtree and Morris in iridium complexes and its relevance in mediating the heterolytic splitting of H2 assisted by a base has been proposed. " Scheme 138 illustrates this intriguing H-bonding. 

Protonic-hydridic interactions are also referred as dihydrogen bonding . 

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