Synthesis and Structure of an Aluminium-Nitrogen Heteronorbornane with Bulky tButyl Substituents and the Crystal Structure of Tri(tbutyl)aluminium

Abstract

The reaction of bis(lithiomethyl-methylamino)methane with ditbutylaluminium chloride leads to the formation of 3,3,6,6-tetra-tbutyl-1,4-dimethyl-3,6-dialumina-1,4-diaza-norbornane by simultaneous formation of two metal-carbon and two metal nitrogen bonds accompanied by two ring closure reactions. The compound was identified by an NMR analysis (1H, 13C, 27Al) and by determination of its crystal structure. Despite the high steric demand of the tbutyl groups, the norbornane-basket structure is favoured over potential isomers containing three-membered rings and over polymeric aggregation. The crystal structure of tri(tbutyl)aluminium has been determined. tBu3Al crystallizes as a monomer, with the molecules interconnected by weak secondary Al···C contacts (2.95 Å) leading to a slight deviation of the AlC3 units from a planar coordination geometry at the Al atoms