Isolation and chemistry of aluminum compounds containing (S)-3,3′-bis(triphenylsilyl)-1,1′-bi-2,2′-naphthoxide ligands

The reaction of the resolved, bulky binol (S)-3,3'-bis(triphenylsilyl)-2,2'-dihydroxy-1,1'-binaphthyl, (S)-H2O2C20H{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[Al-2(O2C20H10{SiPh3}(2)-3,3')(CH3)(4)], (S)-2. Compound 2 contains a [Al(mu-C)(mu-O)] core, Al-Al = 2.739(2) Angstrom, 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 similar to107degrees. 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 305degrees and 322degrees 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.