332844-46-9Relevant academic research and scientific papers
Neutral and cationic organometallic aluminium and indium complexes of mono-pendant arm triazacyclononane ligands
Robson, David A.,Bylikin, Sergei Y.,Cantuel, Martine,Male, Nigel A.H.,Rees, Leigh H.,Mountford, Philip,Schroeder, Martin
, p. 157 - 169 (2001)
Organometallic monomeric and dimeric, neutral and cationic, κ2- and κ4-coordinated mono-pendant arm triazacyclononane complexes of aluminium and indium have been prepared, along with three new mono-pendant arm triazacyclononane ligand precursors HL4, HL5 and HL6 (HL4 = 1-(2-hydroxy-2-methylethyl)-4,7-diisopropyl-1,4,7-triazacyclononane; HL5 = 1-(2-hydroxy-2-methylethyl)-4,7-dimethyl-1,4,7-triazacyclononane; HL6 = 1-(2-hydroxy-2,2-diphenylethyl)-4,7-diisopropyl-1,4,7-triazacyclononane). Reaction of HL4 or HL5 with AlMe3 or AlMe3·py gives the μ-alkoxide bridged dimeric complexes [Al2(κ2-L4)2Me4] and [Al2(κ2-L5)2Me4]. Reaction of HL4 with two equivalents of AlMe3 gives the monomeric compound [Al(κ2-L4·AlMe3)Me2] which can also be prepared by treating [Al2(κ2-L4)2Me4] with two equivalents of AlMe3. Reaction of HL2 with AlMe3·py gives [Al(κ2-L2)Me2], whereas AlMe3 reacts with one or two equivalents of HL1 to give exclusively [Al(κ2-L1)2Me] which contains two κ2-L1 ligands (HL1 = 1-(2-hydroxy-3,5-dimethylbenzyl)-4,7-diisopropyl-1,4,7-triazacyclononane; L2 = 1-(3,5-di-tert-butyl-2-hydroxybenzyl)-4,7-diisopropyl-1,4,7-triazacyclononane). Reaction of AlMe3 with HL6 gives low yields of the monomeric derivative [Al(κ2-L6)Me2]. The κ2-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(κ2-L4·AlMe3)Me2] or [Al(κ2-L2)Me2] using B(C6F5)3 gives the κ4-coordinated cationic derivatives [Al(κ4-L2)Me][MeB(C6F5)3 ] and [Al(κ4-L4·AlMe3)Me][MeB(C6 F5)3], and the latter undergoes reaction with pyridine or MeCN to form [Al(κ4-L4)Me][MeB(C6F5)3 ]. The cationic centres in the last three compounds are unreactive to unsaturated substrates and aprotic Lewis bases. Reaction of In(CH2Ph)3 with HL1 or HL2 affords the four-coordinate complexes [In(κ2-L1)(CH2Ph)2] and [In(κ2-L2)(CH2Ph)2] in which the L1,2 ligand is κ2 bound to In. With the sterically less demanding HL3 [1-(3,5-di-tert-butyl-2-hydroxybenzyl)-4,7-dimethyl-1,4,7-triazacyclononane], however, the six-coordinate complex [In(κ4-L3)(CH2Ph)2] is formed. The compound [In(κ2-L2)(CH2Ph)2] reacts with B(C6F5)3 to form [In(κ4-L2)(CH2Ph)][(PhCH2)B(C 6F5)3].
