7 research outputs found
Monomeric Group 13 Metal(I) Amides: Enforcing One-Coordination Through Extreme Ligand Steric Bulk
Reactions of the extremely bulky amido alkali metal complexes,
[KL′(η<sup>6</sup>-toluene)], or in situ generated [LiL′]
or [LiL″] {L′/ L″ = NÂ(Ar*)Â(SiR<sub>3</sub>),
where Ar* = C<sub>6</sub>H<sub>2</sub>Â{CÂ(H)ÂPh<sub>2</sub>}<sub>2</sub>ÂMe-2,6,4 and R = Me (L′) or Ph (L″)}
with group 13 metalÂ(I) halides have yielded a series of monomeric
metalÂ(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 indiumÂ(I) amide. Attempts to extend this study to the
preparation of the analogous aluminumÂ(I) amide, [AlL′], were
not successful. Despite this, a range of novel and potentially synthetically
useful aluminumÂ(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>Â(μ-H)ÂLiÂ(OEt<sub>2</sub>)<sub>2</sub>Â(THF)] and [{L′AlÂ(μ-H)<sub>3</sub>K}<sub>2</sub>], the neutral amido-aluminum hydride complex,
[{L′AlHÂ(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
Monomeric Group 13 Metal(I) Amides: Enforcing One-Coordination Through Extreme Ligand Steric Bulk
Reactions of the extremely bulky amido alkali metal complexes,
[KL′(η<sup>6</sup>-toluene)], or in situ generated [LiL′]
or [LiL″] {L′/ L″ = NÂ(Ar*)Â(SiR<sub>3</sub>),
where Ar* = C<sub>6</sub>H<sub>2</sub>Â{CÂ(H)ÂPh<sub>2</sub>}<sub>2</sub>ÂMe-2,6,4 and R = Me (L′) or Ph (L″)}
with group 13 metalÂ(I) halides have yielded a series of monomeric
metalÂ(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 indiumÂ(I) amide. Attempts to extend this study to the
preparation of the analogous aluminumÂ(I) amide, [AlL′], were
not successful. Despite this, a range of novel and potentially synthetically
useful aluminumÂ(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>Â(μ-H)ÂLiÂ(OEt<sub>2</sub>)<sub>2</sub>Â(THF)] and [{L′AlÂ(μ-H)<sub>3</sub>K}<sub>2</sub>], the neutral amido-aluminum hydride complex,
[{L′AlHÂ(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
Oxidative Bond Formation and Reductive Bond Cleavage at Main Group Metal Centers: Reactivity of Five-Valence-Electron MX<sub>2</sub> Radicals
Monomeric five-valence-electron bisÂ(boryl)
complexes of gallium,
indium, and thallium undergo oxidative M–C bond formation with
2,3-dimethylbutadiene, in a manner consistent with both the redox
properties expected for M<sup>II</sup> species and with metal-centered
radical character. The weaker nature of the M–C bond for the
heavier two elements leads to the observation of reversibility in
M–C bond formation (for indium) and to the isolation of products
resulting from subsequent B–C reductive elimination (for both
indium and thallium)
Oxidative Bond Formation and Reductive Bond Cleavage at Main Group Metal Centers: Reactivity of Five-Valence-Electron MX<sub>2</sub> Radicals
Monomeric five-valence-electron bisÂ(boryl)
complexes of gallium,
indium, and thallium undergo oxidative M–C bond formation with
2,3-dimethylbutadiene, in a manner consistent with both the redox
properties expected for M<sup>II</sup> species and with metal-centered
radical character. The weaker nature of the M–C bond for the
heavier two elements leads to the observation of reversibility in
M–C bond formation (for indium) and to the isolation of products
resulting from subsequent B–C reductive elimination (for both
indium and thallium)
Oxidative Bond Formation and Reductive Bond Cleavage at Main Group Metal Centers: Reactivity of Five-Valence-Electron MX<sub>2</sub> Radicals
Monomeric five-valence-electron bisÂ(boryl)
complexes of gallium,
indium, and thallium undergo oxidative M–C bond formation with
2,3-dimethylbutadiene, in a manner consistent with both the redox
properties expected for M<sup>II</sup> species and with metal-centered
radical character. The weaker nature of the M–C bond for the
heavier two elements leads to the observation of reversibility in
M–C bond formation (for indium) and to the isolation of products
resulting from subsequent B–C reductive elimination (for both
indium and thallium)
A Stable Two-Coordinate Acyclic Silylene
Simple two-coordinate acyclic silylenes, SiR<sub>2</sub>, have
hitherto been identified only as transient intermediates or thermally
labile species. By making use of the strong σ-donor properties
and high steric loading of the BÂ(NDippCH)<sub>2</sub> substituent
(Dipp = 2,6-<sup><i>i</i></sup>Pr<sub>2</sub>C<sub>6</sub>H<sub>3</sub>), an isolable monomeric species, SiÂ{BÂ(NDippCH)<sub>2</sub>}Â{NÂ(SiMe<sub>3</sub>)ÂDipp}, can be synthesized which is stable
in the solid state up to 130 °C. This silylene species undergoes
facile oxidative addition reactions with dihydrogen (at sub-ambient
temperatures) and with alkyl C–H bonds, consistent with a low
singlet–triplet gap (103.9 kJ mol<sup>–1</sup>), thus
demonstrating fundamental modes of reactivity more characteristic
of transition metal systems
A Stable Two-Coordinate Acyclic Silylene
Simple two-coordinate acyclic silylenes, SiR<sub>2</sub>, have
hitherto been identified only as transient intermediates or thermally
labile species. By making use of the strong σ-donor properties
and high steric loading of the BÂ(NDippCH)<sub>2</sub> substituent
(Dipp = 2,6-<sup><i>i</i></sup>Pr<sub>2</sub>C<sub>6</sub>H<sub>3</sub>), an isolable monomeric species, SiÂ{BÂ(NDippCH)<sub>2</sub>}Â{NÂ(SiMe<sub>3</sub>)ÂDipp}, can be synthesized which is stable
in the solid state up to 130 °C. This silylene species undergoes
facile oxidative addition reactions with dihydrogen (at sub-ambient
temperatures) and with alkyl C–H bonds, consistent with a low
singlet–triplet gap (103.9 kJ mol<sup>–1</sup>), thus
demonstrating fundamental modes of reactivity more characteristic
of transition metal systems