Phosphine-Stabilized Germylidenylpnictinidenes as Synthetic Equivalents of Heavier Nitrile and Isocyanide in Cycloaddition Reactions with Alkynes

Abstract

The reactions of chlorogermylene MsFluind tBu-GeCl 1, supported by a sterically encumbered hydrindacene ligand MsFluind tBu, with NaPCO­(dioxane)2.5 and NaAsCO­(18-c-6) in the presence of trimethylphosphine afforded trimethylphosphine-stabilized germylidenyl-phosphinidene 2 and -arsinidene 3, respectively. Structural and computational investigations reveal that the Ge–E′ bond (E′ = P and As) features a multiple-bond character. 2 and 3 exhibit diverse reactivity toward trimethylsilylacetylene and 4-tetrabutylphenylacetylene. Specifically, 2 underwent cycloadditions with both alkynes affording the first six-membered aromatic phosphagermabenzen-1-ylidenes 4 and 5, respectively, through the heavier isocyanide intermediate MsFluind tBu-PGe. In contrast, 3 could serve as a synthetic equivalent of heavier isocyanides and nitriles when treated with trimethylsilylacetylene and 4-tetrabutylphenylacetylene yielding arsagermene 6 and arsolylgermylene 7, respectively. The reaction mechanisms for the cycloadditions were investigated through density functional theory calculations. The reactivity studies highlight the potential of 2 and 3 in accessing heavy main-group element-containing heterocycles.

Structural Snapshots in Reversible Phosphinidene Transfer: Synthetic, Structural, and Reaction Chemistry of a Sn═P Double Bond

“…Inoue and Tan have recently reported the syntheses of germanium and tin compounds (e.g., II ) that show short E 14 –P bonds and can be described in terms of a resonance contribution involving an EP double bond . In this context, Inoue and co-workers were able to characterize a zwitterionic stannaphosphene by reacting compound II with B­(C 6 F 5 ) 3 .…”

A germanimidoyl chloride: synthesis, characterization and reactivity

“…Herein, we report the synthesis, characterization and reactivity of the first germanimidoyl chloride M s Fluind tBu -Ge(Cl)QNMes (2) (Scheme 1, where M s Fluind tBu is a bulky hydrindacene skeleton). 26 The reactions of 2 with Ar 0 Li (Ar 0 = 3,5-t Bu 2 C 6 H 3 ) furnished germanimine M s Fluind tBu -Ge(Ar 0 )QNMes (5). Treatment of 2 with MeLi afforded the amide lithium salt M s Fluind tBu -Ge(Me) 2 -N(Mes)Li(thf) (6).…”

“…20 The distances of Ge1-Cl1 (2.2043(12) Å) and Ge1-C1 (1.931(4) Å) are both slightly shorter than those found in the precursor M s Fluind tBu -GeCl (Ge-Cl: 2.2500(6) Å; Ge-C: 2.007(2) Å). 26 To gain better insights into the electronic structure of 2, we performed density functional theory calculations. The structure was optimized at the oB97XD/6-31G(d) level of theory.…”

“…The targeted germanimidoyl chloride M s Fluind t Bu -Ge(Cl)NMes ( 2 ) was synthesized through the reaction of M s Fluind t Bu -GeCl ( 1 ) 26 and 1 molar equivalent of mesityl azide (MesN 3 ) with concomitant elimination of N 2 (Scheme 1). Compound 2 was isolated as orange crystals in 73% yield.…”

“…20 The distances of Ge1–Cl1 (2.2043(12) Å) and Ge1–C1 (1.931(4) Å) are both slightly shorter than those found in the precursor M s Fluind t Bu -GeCl (Ge–Cl: 2.2500(6) Å; Ge–C: 2.007(2) Å). 26…”