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Isolation and Chemistry of Aluminum Compounds Containing (S)-3,3‘-Bis(triphenylsilyl)-1,1‘-bi-2,2‘-naphthoxide Ligands

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journal contribution
posted on 29.04.2003, 00:00 by Au Ji Ru Son, Matthew G. Thorn, Phillip E. Fanwick, Ian P. Rothwell
The reaction of the resolved, bulky binol (S)-3,3‘-bis(triphenylsilyl)-2,2‘-dihydroxy-1,1‘-binaphthyl, (S)-H2O2C20H10{SiPh3}2-3,3‘ (1), with a variety of alkyl and amide compounds has been investigated. Reaction of 1 with [Al2Me6] initially proceeds only in a 1:1 ratio to produce dinuclear [Al2(O2C20H10{SiPh3}2-3,3‘)(CH3)4], (S)-2. Compound 2 contains a [Al(μ-C)(μ-O)] core, Al−Al = 2.739(2) Å, with the binaphthoxide ligand oxygen atoms occupying terminal and bridging positions. In the presence of pyridine, 2 reacts further with 1 to produce [Al(O2C20H10{SiPh3}2-3,3‘)(CH3)(py)], (S)-4. The ethyl analogue of 4, [Al(O2C20H10{SiPh3}2-3,3‘)(CH3)(py)], (S)-5, was obtained from [Et2AlCl]. Both 4 and 5 were shown to adopt tetrahedral geometries in the solid state with O−Al−O angles of ∼107°. Reaction of [LiAl(NMe2)4] with 1 produced a dinuclear compound, [LiAl(O2C20H10{SiPh3}2-3,3‘)(NHMe2)(NMe2)2], (S)-6, containing a terminal and bridging amido group. The lithium-bound HNMe2 ligand could be substituted by pyridine to produce [LiAl(O2C20H10{SiPh3}2-3,3‘)(NC6H5)(NMe2)2], (S)-7. In the solid state the formally three-coordinated lithium atoms in 6 and 7 are pyramidalized. The sum of the three angles for the LiN2O core is 305° and 322° for 6 and 7, respectively. This is due to an interaction of the lithium with one arene ring of an SiPh3 group. In 6 the carbon atoms involved are an ipso- and ortho-carbon, while for 7 the ortho- and meta-carbon atoms of a Ph−Si ring are in close contact.