Crystalline Complexes of Pyr_12O1TFSI-Based Ionic Liquid Electrolytes

This study examines the formation of previously unreported crystalline phases of <i>N</i>-methoxyethyl-<i>N</i>-methylpyrrolidinium bis­(trifluoromethanesulfonyl)­imide (Pyr_12O1TFSI). The melting point of pristine Pyr_12O1TFSI, determined by conductivity measurements, is between −20 and −17.5 °C. Formation of this crystalline phase is difficult and only occurs under specific conditions. Pyr_12O1TFSI readily forms 1:1 phases with both NaTFSI and Mg­(TFSI)_2. The results of single crystal structure determinations are presented. The Na⁺ crystalline phase provides clear evidence that the Pyr_12O1⁺ cation can coordinate some metal ions, but this coordinative interaction does not occur with all metal cations, e.g., Mg²⁺, and in all states of matter, e.g., Na⁺-IL solutions. The TFSI^– ions are found in two different aggregate solvates in the Pyr_12O1TFSI:NaTFSI 1:1 phase and in contact ion pair and aggregate solvates in the Pyr_12O1TFSI:Mg­(TFSI)₂ 1:1 phase. The Pyr_12O1TFSI:Mg­(TFSI)₂ crystalline phase gives insight into the local structure of the liquid electrolyte, where it is likely that a maximum of approximately 30% of the total TFSI^– can likely be coordinated in a bridging geometry, and the rest are in a bidentate coordination geometry. This ratio is determined from both the crystal structure and the Raman spectroscopy results

Cooperative Ge–N Bond Activation in Hydrogallation Products of Alkynyl(diethylamino)germanes (Et₂N)_<i>n</i>Ge(CC^<i>t</i>Bu)_4–<i>n</i>

Treatment of the alkynyl­(diethylamino)­germanes Et₂NGe­(CC^<i>t</i>Bu)₃ (<b>1</b>) and (Et₂N)₂Ge­(CC^<i>t</i>Bu)₂ (<b>2</b>) with dialkylelement hydrides ^<i>t</i>Bu₂MH (M = Al, Ga) afforded in high yields the hydrometalation products (^<i>t</i>BuCC)₂(Et₂N)­Ge­[C­(M^<i>t</i>Bu₂)C­(H)^<i>t</i>Bu] (<b>3</b>), (^<i>t</i>BuCC)­(Et₂N)­Ge­[C­(M^<i>t</i>Bu₂)C­(H)^<i>t</i>Bu]₂ (<b>4</b>) and (^<i>t</i>BuCC)­(Et₂N)₂Ge­[C­(Ga^<i>t</i>Bu₂)C­(H)^<i>t</i>Bu] (<b>6</b>). The Lewis acidic aluminum and gallium atoms showed a close contact to the nitrogen atoms of the amino groups attached to germanium, which resulted in relatively long Ge–N bonds and short Al–N or Ga–N distances. The structures of these molecules and the strengths of the interactions were investigated by dispersion-corrected density functional theory. This activation of the Ge–N bonds caused an unprecedented reactivity of compounds <b>4b</b> and <b>6</b>. <b>4b</b> reacted with PhCCH under mild conditions and elimination of HNEt₂ to give the mixed dialkynyl compound (^<i>t</i>BuCC)­(PhCC)­Ge­[C­(Ga^<i>t</i>Bu₂)C­(H)^<i>t</i>Bu]₂ (<b>5</b>), while facile insertion of RNCX into a Ge–N bond of <b>6</b> led to the formation of the six-membered Ge–C–Ga–X–C–N heterocycles <b>7</b> (R = Ph, Et; X = O, S)

Cooperative Ge–N Bond Activation in Hydrogallation Products of Alkynyl(diethylamino)germanes (Et₂N)_<i>n</i>Ge(CC^<i>t</i>Bu)_4–<i>n</i>

Treatment of the alkynyl­(diethylamino)­germanes Et₂NGe­(CC^<i>t</i>Bu)₃ (<b>1</b>) and (Et₂N)₂Ge­(CC^<i>t</i>Bu)₂ (<b>2</b>) with dialkylelement hydrides ^<i>t</i>Bu₂MH (M = Al, Ga) afforded in high yields the hydrometalation products (^<i>t</i>BuCC)₂(Et₂N)­Ge­[C­(M^<i>t</i>Bu₂)C­(H)^<i>t</i>Bu] (<b>3</b>), (^<i>t</i>BuCC)­(Et₂N)­Ge­[C­(M^<i>t</i>Bu₂)C­(H)^<i>t</i>Bu]₂ (<b>4</b>) and (^<i>t</i>BuCC)­(Et₂N)₂Ge­[C­(Ga^<i>t</i>Bu₂)C­(H)^<i>t</i>Bu] (<b>6</b>). The Lewis acidic aluminum and gallium atoms showed a close contact to the nitrogen atoms of the amino groups attached to germanium, which resulted in relatively long Ge–N bonds and short Al–N or Ga–N distances. The structures of these molecules and the strengths of the interactions were investigated by dispersion-corrected density functional theory. This activation of the Ge–N bonds caused an unprecedented reactivity of compounds <b>4b</b> and <b>6</b>. <b>4b</b> reacted with PhCCH under mild conditions and elimination of HNEt₂ to give the mixed dialkynyl compound (^<i>t</i>BuCC)­(PhCC)­Ge­[C­(Ga^<i>t</i>Bu₂)C­(H)^<i>t</i>Bu]₂ (<b>5</b>), while facile insertion of RNCX into a Ge–N bond of <b>6</b> led to the formation of the six-membered Ge–C–Ga–X–C–N heterocycles <b>7</b> (R = Ph, Et; X = O, S)

Al/P-Based Frustrated Lewis Pairs: Limitations of Their Synthesis by Hydroalumination and Formation of Dialkylaluminum Hydride Adducts

Aluminum–phosphorus-based frustrated Lewis pairs (Al/P FLPs) are valuable reagents for the dipolar activation or coordination of small molecules or ionic compounds. They are accessible by hydroalumination of alkynylphosphines. However, as reported in this article, the application of this simple method for the synthesis of a broad variety of different compounds is limited to sterically shielded systems. Hydroalumination of Mes₂PCCPh with small dialkyl- or diarylaluminum hydrides HAlR₂ (R = Me, <i>i</i>Bu, Ph) afforded unique adducts in which an HAlR₂ molecule was coordinated by the Al/P FLP Mes₂PC­(CHPh)­AlR₂ via an Al–P and an Al–H–Al 3c bond. A new Al/P FLP was obtained with equimolar quantities of dineopentylaluminum hydride. The less shielded alkynylphosphine Ph₂PCCPh yielded a hydride adduct with HAlNp₂ and an alkyne adduct with HAl<i>t</i>Bu₂. The latter compound resulted from triple-bond activation and had a five-membered AlPC₃ heterocycle in which a CC bond was bonded to the P and Al atoms of an Al/P FLP. Both compounds were isolated in high yields by application of the appropriate stoichiometric ratios of the starting materials