Synthesis and Characterization of Thermally Robust Amidinato Group 13 Hydride Complexes

The reactivity of two sterically bulky amidines, ArNC(R)N(H)Ar (Ar=2,6‐diisopropylphenyl; R=H (HFiso); tBu, (HPiso)) towards LiMH4, M=Al or Ga, [AlH3(NMe3)], and [GaH3(quin)] (quin=quinuclidine) has been examined. This has given rise to a variety of very thermally stable aluminum and gallium hydride...

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Veröffentlicht in:Chemistry : a European journal 2005-07, Vol.11 (15), p.4482-4491
Hauptverfasser: Cole, Marcus L., Jones, Cameron, Junk, Peter C., Kloth, Marc, Stasch, Andreas
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Sprache:eng
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Zusammenfassung:The reactivity of two sterically bulky amidines, ArNC(R)N(H)Ar (Ar=2,6‐diisopropylphenyl; R=H (HFiso); tBu, (HPiso)) towards LiMH4, M=Al or Ga, [AlH3(NMe3)], and [GaH3(quin)] (quin=quinuclidine) has been examined. This has given rise to a variety of very thermally stable aluminum and gallium hydride complexes. The structural motif adopted by the prepared complexes has been found to be dependent upon both the amidinate ligand and the metal involved. The 1:1 reaction of HFiso with LiAlH4 yielded dimeric [{AlH3(μ‐Fiso)Li(OEt2)}2]. Amidine HFiso reacts in a 1:1 ratio with [AlH3(NMe3)] to give the unusual hydride‐bridging dimeric complex, [{AlH2(Fiso)}2], in which the Fiso− ligand is nonchelating. The equivalent reaction with the bulkier amidine, HPiso, yielded a related hydride‐bridging complex, [{AlH2(Piso)}2], in which the Piso− ligand is chelating. In contrast, the treatment of [GaH3(quin)] with one equivalent of HFiso afforded the four‐coordinate complex [GaH2(quin)(Fiso)], in which the Fiso− ligand acts as a localized monodentate amido–imine ligand. The 2:1 reactions of HFiso with [AlH3(NMe3)] or [GaH3(quin)] gave the monomeric complexes [MH(Fiso)2], which are thermally robust and which exhibit chelating amidinate ligands. In contrast, HPiso did not give 2:1 complexes in its reactions with either of the Group 13 trihydride precursors. For sake of comparison, the reactions of [AlH3(NMe3)] and [GaH3(quin)] with the bulky carbodiimide ArNCNAr and the thiourea Ar(H)NC(S)N(H)Ar were examined. These last reactions afforded the five‐coordinate thioureido complexes, [MH{N(Ar)C[N(H)(Ar)]S}2], M=Al or Ga. Variety is the spice of life: The reactions of two bulky amidines with aluminum and gallium hydride complexes have produced a series of amidinato Group 13 hydride complexes which display good thermal stability and a variety of structural motifs.
ISSN:0947-6539
1521-3765
DOI:10.1002/chem.200500278