SYNTHESES AND MOLECULAR-STRUCTURES OF MULTINUCLEAR ALUMINUM COMPLEXES RN+2ALNL2 (N=3,4 L=DIAMINE, TRIAMINE) CONTAINING PENTACOORDINATE ALUMINUM ATOMS

Reactions of Al2R'4[N(C2H5)2]2 (R' = CH3, C2H5) with ethylenediamine or N,N'-dimethylethylenediamine yield air-sensitive trialuminium products [AlR'2]2[RNCH2 CH2NR]2[AlR'] (1a: R'= CH3, R = H; 1b: R'= CH3, R = CH3; 2a: R'= C2H5, R = H; 2b: R'= C2H5, R = CH3). Reactions of Al2R'4[N(C2H5)2]2 with diethylenetriamine, [(NH2CH2CH2)2NH], yield air-sensitive tetraaluminium products, (AlR'2)2 [(HNCH2CH2)2N]2(AlR')2 (3: R'= CH3; 4: R'= C2H5). The polyaluminium complexes are well characterized. Some structures have been determined by X-ray crystallography. For both 1a and 1b the penta-coordination sphere around the central aluminium conforms to a square-pyramidal configuration and the tetra-coordination for the outer two aluminium atoms is a tetrahedral configuration. Complex 4 has two central aluminium atoms with a penta-coordinate square-pyramidal configuration and the outer aluminium atoms in a tetrahedral configuration.