Alane bonds interaction

The reaction between a Lewis acid R3M and a Lewis base ER3 is of fundamental interest in main group chemistry. Synthetic and computational chemists have investigated the influence of both the Lewis acid and the base on the solid state structure and the thermodynamic stability of the corresponding adduct, that is usually expressed in terms of the dissociation enthalpy De. This led to a sophisticated understanding of the nature of dative bonding interactions. In particular, reactions of boranes, alanes and gallanes MR3 with amines and phosphines ER3, typically leading to adducts of the type R3M <— ER3, have been studied.10... 

According to the Haaland model, an increase of the Lewis acid-base interaction is accompanied by a decrease of both the R—Al—R bond angles and the Al—R bond distances. However, comparisons are possible only for adducts containing the same alane to exclude any steric or electronic effects of... 

Steric interactions between bulky substituents such as t-Bu, leading to larger C-E-C bond angles, obviously affect the Lewis basicity caused by the increased -character of the electron lone pair. However, the strength of the Lewis acid-base interaction within an adduct as expressed by its dissociation enthalpy does not necessarily reflect the Lewis acidity and basicity of the pure fragments, because steric (repulsive) interactions between the substituents bound to both central elements may play a contradictory role. In particular, adducts containing small group 13/15 elements are very sensitive to such interactions as was shown for amine-borane and -alane adducts... 

Catalyst mixtures with discrete rare-earth metal components featuring preformed Ln - H bonds have not been employed in diene polymerization. Therefore, in this section the interaction of purely inorganic aluminohydrides (alanes) with organolanthanide compounds will be only briefly addressed, as well as the utilization of borohydrides in the fabrication of polydienes. 

Complexes with one and two amines are common. For example, bis-(trimethylamine) alane, A1H3(N(CH3)3)2, is a white crystalline solid with a low vapor pressure. Using ammonia as a model for trimethylamine, apply orbital interaction analysis to describe the bonding in the 1 1 and 1 2 complexes. Theoretical studies on the ammonia complexes of AIH3 have led to the conclusion that there is little dative bonding (as judged by the amount of charge transfer) (Marsh, C. M, B. Schaefer III, H. F., J. Phys. Chem., 1995, 99, 14309-14315). Comment on the theoretical results. 

By the interaction of sulfur dioxide and trialkyl alanes, when the A1—C bond is added across the S—0 bond, alkyl sulfinates of aluminum are obtained (231, 313). The analogous reaction with 3 moles of sulfur trioxide leads to alkyl sulfonates (19) ... 

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