Neutral and cationic organometallic aluminium and indium complexes of mono-pendant arm triazacyclononane ligands
Organometallic monomeric and dimeric, neutral and cationic, κ 2- and κ 4-coordinated mono-pendant arm triazacyclononane complexes of aluminium and indium have been prepared, along with three new mono-pendant arm triazacyclononane ligand precursors HL...
| Main Authors: | , , , , , , |
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| Format: | Journal article |
| Language: | English |
| Published: |
2001
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| Summary: | Organometallic monomeric and dimeric, neutral and cationic, κ 2- and κ 4-coordinated mono-pendant arm triazacyclononane complexes of aluminium and indium have been prepared, along with three new mono-pendant arm triazacyclononane ligand precursors HL 4, HL 5 and HL 6 (HL 4 = 1-(2-hydroxy-2-methylethyl)-4,7-diisopropyl-1,4,7-triazacyclononane; HL 5 = 1-(2-hydroxy-2-methylethyl)-4,7-dimethyl-1,4,7-triazacyclononane; HL 6 = 1-(2-hydroxy-2,2-diphenylethyl)-4,7-diisopropyl-1,4,7-triazacyclononane) . Reaction of HL 4 or HL 5 with AlMe 3 or AlMe 3·py gives the μ-alkoxide bridged dimeric complexes [Al 2(κ 2-L 4) 2Me 4 ] and [Al 2(κ 2-L 5) 2Me 4 ]. Reaction of HL 4 with two equivalents of AlMe 3 gives the monomeric compound [Al(κ 2-L 4·AlMe 3)Me 2 ] which can also be prepared by treating [Al 2(κ 2-L 4) 2Me 4 ] with two equivalents of AlMe 3. Reaction of HL 2 with AlMe 3·py gives [Al(κ 2-L 2)Me 2], whereas AlMe 3 reacts with one or two equivalents of HL 1 to give exclusively [Al(κ 2-L 1) 2Me] which contains two κ 2-L 1 ligands (HL 1 = 1-(2-hydroxy-3,5-dimethylbenzyl)-4,7-diisopropyl-1,4,7-triazacyclononane ; L 2 = 1-(3,5-di-tert-butyl-2-hydroxybenzyl)-4,7-diisopropyl-1,4,7-triazacyclon onane). Reaction of AlMe 3 with HL 6 gives low yields of the monomeric derivative [Al(κ 2-L 6)Me 2]. The κ 2-coordination mode of the triazacyclononane ligands in all these compounds is unique in the chemisty of these ligands. The crystal structures of four of them are discussed. Methyl group abstraction from [Al(κ 2-L 4·AlMe 3)Me 2 ] or [Al(κ 2-L 2)Me 2] using B(C 6F 5) 3 gives the κ 4-coordinated cationic derivatives [Al(κ 4-L 2)Me][MeB(C 6F 5 ) 3] and [Al(κ 4-L 4-AlMe 3)Me][MeB(C 6 F 5) 3], and the latter undergoes reaction with pyridine or MeCN to form [Al(κ 4-L 4)Me][MeB(C 6F 5 ) 3]. The cationic centres in the last three compounds are unreactive to unsaturated substrates and aprotic Lewis bases. Reaction of In(CH 2Ph) 3 with HL 1 or HL 2 affords the four-coordinate complexes [In(κ 2-L 1)(CH 2Ph) 2] and [In(κ 2-L 2)(CH 2Ph) 2] in which the L 1,2 ligand is κ 2 bound to In. With the sterically less demanding HL 3 [1-(3,5-di-tert-butyl-2-hydroxybenzyl)-4,7-dimethyl-1,4,7-triazacyclonon ane], however, the six-coordinate complex [In(κ 4-L 3)(CH 2Ph) 2] is formed. The compound [In(κ 2-L 2)(CH 2Ph) 2] reacts with B(C 6F 5) 3 to form [In(κ 4-L 2)(CH 2Ph)][(PhCH 2 )B(C 6F 5) 3]. © The Royal Society of Chemistry 2001. |
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