A Phosphanyl‐Phosphagallene that Functions as a Frustrated Lewis Pair

Abstract

Phosphagallenes (1 a/1 b) featuring double bonds between phosphorus and gallium were synthesized by reaction of (phosphanyl)phosphaketenes with the gallium carbenoid Ga(Nacnac) (Nacnac=HC[C(Me)N(2,6‐i‐Pr2C6H3)]2). The stability of these species is dependent on the saturation of the phosphanyl moiety. 1 a, which bears an unsaturated phosphanyl ring, rearranges in solution to yield a spirocyclic compound (2) which contains a P=P bond. The saturated variant 1 b is stable even at elevated temperatures. 1 b behaves as a frustrated Lewis pair capable of activation of H2 and forms a 1:1 adduct with CO2.

Synthesis and Reactivity of Heteroleptic Ga‐P‐C Allyl Cation Analogues

“…While homonuclear congeners of alkenes are well known, [2] heteronuclear group 13–15 compounds with M=E double bond (M=B−Tl; E=N−Bi), which are isovalence‐electronic to C−C bonded species, [3] are almost limited to borapnictenes with B−E (E=N, P, As) [4] and metallaimines with M−N (M=Al, Ga, In) double bonds [5] . Analogous π‐bonded heavier congeners are still rare and only one gallaphosphene, [6] three gallaarsenes [7] and five gallastibenes were structurally characterized [8]…”

From π‐Bonded Gallapnictenes to Nucleophilic, Redox‐Active Metal‐Coordinated Pnictanides

“…Recently, Goicoechea et al. reported the synthesis of neutral phosphanyl‐phoshagallenes with Ga−P double bond (type II ), [7] while we established a general route to gallapnictenes LGaEGa(X)L (E=As, X=Cl, Br; E=Sb, X=F, Cl, Br, I; type III ) [8] and LGaER (ER=AsCp*, SbTer; Ter=2,6‐Mes 2 C 6 H 3 ; Mes=2,4,6‐Me 3 C 6 H 2 ; type II ) [9] by reaction of gallanediyl LGa with pnictanes. While several compounds of types II and III were structurally characterized, their reactivity is almost unknown.…”

“…While several compounds of types II and III were structurally characterized, their reactivity is almost unknown. Phosphanyl‐phoshagallene [(H 2 C) 2 (NAr) 2 P]PGaL (Ar=Dip) [7] (type II ) reacted with small molecules (H 2 , CO 2 ) like a frustrated Lewis pair in 1,3 position (P‐P‐Ga) rather than at the P−Ga double bond due to the presence of the Lewis‐basic phosphanyl group. Based on results from DFT calculations, the pnictogene atoms in LGaEGa(Cl)L (E=As, Sb, type III ) are expected to exhibit nucleophilic character, whereas the π‐bonded Ga atom is electrophilic as indicated by the strongly polarized Ga−E π‐bonds (Ga 18 %, As 84 %; Ga 17 %, Sb 83 %) (Table S26) and the natural charges (Ga 1.27 e, As −1.00 e; Ga 1.12 e, Sb −0.71 e) (Table S25) [18] .…”

Von π‐gebundenen Gallapnictenen zu nukleophilen, redoxaktiven metallkoordinierten Pnictid‐Anionen

“…ein neutrales Phosphanylphoshagallen mit einer Ga‐P‐Doppelbindung (Typ II ) [7] synthetisiert, während wir durch Reaktionen des Gallanediyls LGa mit verschiedenen Pnictanen einen generellen Zugang zu Gallapnictenen der Form LGaEGa(X)L (E=As, X=Cl, Br; E=Sb, X=F, Cl, Br, I; Typ III ) [8] und LGaER (ER=AsCp*, SbTer; Ter=2,6‐Mes 2 C 6 H 3 ; Mes=2,4,6‐Me 3 C 6 H 2 ; Typ II ) [9] etablierten. Obwohl einige Verbindungen des Typs II und III strukturell und spektroskopisch charakterisiert wurden, ist deren Reaktivität nahezu unbekannt und auf Reaktionen des Phosphanylphoshagallens [(H 2 C) 2 (NAr) 2 P]PGaL (Ar=Dip) [7] (Typ II ) mit kleineren Molekülen (H 2 , CO 2 ) beschränkt. Diese reagieren aufgrund der Lewis‐basischen Phosphanylgruppe nicht an der P‐Ga‐Doppelbindung, sondern vorzugsweise als frustiertes Lewis‐Paar in 1,3‐Position.…”