Structure investigations of group 13 organometallic carboxylates.

Iwona Justyniak,Daniel Prochowicz,Piotr Goś,Wojciech Bury,Adam Tulewicz,Janusz Lewiński

doi:10.1039/c6dt03958h

Abstract

The octet-compliant group 13 organometallics with highly polarized bonds in the metal coordination sphere exhibit a significant tendency to maximize their coordination number through the formation of adducts with a wide range of neutral donor ligands or by self-association to give aggregates containing tetrahedral and higher coordinated aluminium centres, and even in some cases molecular complexes equilibrate with ionic species of different coordination numbers of the metal centre. This work provides a comprehensive overview of the structural chemistry landscape of the group 13 carboxylates. Aside from a more systematic approach to the general structural chemistry of the title compounds, the structure investigations of [R2M(μ-O2CPh)]2-type benzoate complexes (where M = B, Al and Ga) and their Lewis acid-base adducts [(R2M)(μ-O2CPh)(py-Me)] are reported. DFT calculations were also performed to obtain a more in-depth understanding of both the changes in the bonding of group 13 organometallic carboxylate adducts with a pyridine ligand.

Highlights

Many efforts have been made in developing convenient, efficient, and useful transformations taking advantage of the electron deficiency caused by the Lewis acidity on the coordination centre of group 13 organometallics.[1,2] This concerns compounds with a low three-coordinate metal centre[2] and the inherent Lewis acidity of electron-deficient metal centres and a vast number of organometallics obeying the octet rule, for which the relative Lewis acidity of a metal centre is essentially not obvious.[1]
Upon dissolution of a dimeric dichloroaluminium carboxylate [Cl2Al(μ-O2CR′)]2 followed by the addition of 4-methylpyridine a six-coordinate Lewis acid–base adduct [Cl2Al(μ-O2CR′)( presence of 4-methylpyridine (py-Me))2] with a chelating carboxylate ligand was formed, whereas the dimer [Cl2Al(μ-O2CR′)]2 equilibrated with an ion-pair [(RCO2)2Al(THF)2+][AlCl4−] in the presence of THF (Scheme 1a).[4]
Aside from the discussion of the structural chemistry landscape of the group 13 carboxylates, we focused on the structure investigations of [R2M(μ-O2CPh)]2-type benzoate complexes and their reactivity towards monodentate Lewis bases

Summary

Introduction

Many efforts have been made in developing convenient, efficient, and useful transformations taking advantage of the electron deficiency caused by the Lewis acidity on the coordination centre of group 13 organometallics.[1,2] This concerns compounds with a low three-coordinate metal centre[2] and the inherent Lewis acidity of electron-deficient metal centres and a vast number of organometallics obeying the octet rule, for which the relative Lewis acidity of a metal centre is essentially not obvious.[1].

Results

Conclusion