Monomeric Group 13 Metal(I)
Amides: Enforcing One-Coordination
Through Extreme Ligand Steric Bulk
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Abstract
Reactions of the extremely bulky amido alkali metal complexes,
[KL′(η<sup>6</sup>-toluene)], or in situ generated [LiL′]
or [LiL″] {L′/ L″ = N(Ar*)(SiR<sub>3</sub>),
where Ar* = C<sub>6</sub>H<sub>2</sub>{C(H)Ph<sub>2</sub>}<sub>2</sub>Me-2,6,4 and R = Me (L′) or Ph (L″)}
with group 13 metal(I) halides have yielded a series of monomeric
metal(I) amide complexes, [ML′] (M = Ga, In, or Tl) and [ML″]
(M = Ga or Tl), all but one of which have been crystallographically
characterized. The results of the crystallographic studies, in combination
with computational analyses, reveal that the metal centers in these
compounds are one coordinate and do not exhibit any significant intra-
or intermolecular interactions, other than their N-M linkages. One
of the complexes, [InL′], represents the first example of a
one-coordinate indium(I) amide. Attempts to extend this study to the
preparation of the analogous aluminum(I) amide, [AlL′], were
not successful. Despite this, a range of novel and potentially synthetically
useful aluminum(III) halide and hydride complexes were prepared en
route to [AlL′], the majority of which were crystallographically
characterized. These include the alkali metal aluminate complexes,
[L′AlH<sub>2</sub>(μ-H)Li(OEt<sub>2</sub>)<sub>2</sub>(THF)] and [{L′Al(μ-H)<sub>3</sub>K}<sub>2</sub>], the neutral amido-aluminum hydride complex,
[{L′AlH(μ-H)}<sub>2</sub>], and the aluminum halide complexes,
[L′AlBr<sub>2</sub>(THF)] and [L′AlI<sub>2</sub>]. Reaction
of the latter two systems with a variety of reducing agents led only
to intractable product mixtures