Recent advances in the chemistry of the phosphaethynolate and arsaethynolate anions

Abstract

Over the past decade, the reactivity of 2-phosphaethynolates (OCP¯), a heavier analogue of the cyanate anion, is the subject of momentous interest in modern organometallic chemistry. Its use as a...

Synthesis and Reactivity of N-Heterocyclic Carbene Coordinated Formal Germanimidoyl-Phosphinidenes

“…The one-pot reaction of chlorogermylene M s Fluid t Bu -GeCl ( 1 , where M s Fluid t Bu is a bulky hydrindacene substituent), NaPCO­(dioxane) 2.5 , and 1,3-diisopropyl-4,5-dimethyl-imidazolin-2-ylidene (NHC i Pr ) under ambient conditions in a dry nitrogen atmosphere afforded NHC-stabilized germylidenylphosphinidene M s Fluid t Bu -GeP­(NHC i Pr ) ( 2 ) in a 69% yield as an orange crystalline solid (Scheme ). The 31 P NMR signal was observed at δ 226.2 ppm (Table ), close to that of a similar core structure TerGeP­(IDipp) (δ 216.8 ppm; Ter = 2,6-Mes 2 C 6 H 3 , IDipp = C­([N-(2,6- i Pr 2 C 6 H 4 )­CH] 2 ) reported by Inoue and co-workers, and within the range reported for phosphagermenes (175–416 ppm)…”

Deciphering the Differences in Ambident Reactivity between the Cyanate, Thiocyanate Ions, and their P‐ and As‐Containing Analogues

“…[45] Indeed, the chemical reactivity of the [PCO] À anion has been explored extensively: In general, the [PCO] À anion can participate in various reactions, including cycloadditions, P À -transfer reactions, and nucleophilic substitutions (S N ). [46][47][48] To our knowledge, only one study deals delicately with nucleophilic substitutions toward C-centred electrophiles (Scheme 1): The [PCO] À anion has been shown to react exclusively on its P centre with simple organic electrophiles, such as i PrÀ I or Tr*À Cl (Tr* = 4,4',4''-trimethoxytriphenylmethyl); however, the initially formed phosphaketenes undergo subsequent cycloaddition reactions. [49] Later, the ambident character of the [PCO] À ion was proven by its reaction with i Pr 3 SiÀ OTf: At room temperature, this reaction leads predominantly to the Osilylated kinetic product, i Pr 3 SiÀ OÀ C�P, which then isomerises to the thermodynamically favoured P-silylated product ( i Pr 3 SiÀ P=C=O).…”

“…(Figure 1B), has also attracted significant interest, [27–44] accelerated by the recent development of straightforward synthetic methods leading to the sodium salt of this anion [45] . Indeed, the chemical reactivity of the [PCO] − anion has been explored extensively: In general, the [PCO] − anion can participate in various reactions, including cycloadditions, P − ‐transfer reactions, and nucleophilic substitutions (S N ) [46–48] …”

Understanding the Mechanism of Diels–Alder Reactions with Anionic Dienophiles: A Systematic Comparison of [ECX]− (E = P, As; X = O, S, Se) Anions

“…During the past decade, the chemistry of the 2-phosphaethynolate ([PCO] − ) anion has gained significant interest from both the experimental and theoretical points of view. − On the basis of its first documentation by Becker et al in 1992, this anion was synthesized in the form of a lithium salt, Li­[OCP] . Even though the potential of low-coordinate phosphorus compounds was clear at that time, the chemistry of the [PCO] − anion remained practically unexplored for a long time, most likely because of the low stability of the lithium salt.…”