Preparation and Characterization of P₂BCh Ring Systems (Ch=S, Se) and Their Reactivity with N‐Heterocyclic Carbenes

Abstract

Four-membered rings with a P BCh core (Ch=S, Se) have been synthesized by the reaction of phosphinidene chalcogenide (Ar*P=Ch) and phosphaborene (Mes*P=BNR ). The mechanistic pathways towards these rings are explained by detailed computational work that confirmed the preference for the formation of P-P, not P-B, bonded systems, which seems counterintuitive given that both phosphorus atoms contain bulky ligands. The reactivity of the newly synthesized heterocycles, as well as that of the known (RPCh) rings (n=2, 3), was probed by the addition of N-heterocyclic carbenes, which revealed that all investigated compounds can act as sources of low-coordinate phosphorus species.

N‐Heterocyclic Carbene–Phosphinidene Adducts: Synthesis, Properties, and Applications

“…Ragogna and co‐workers discovered that the related phosphinidene selenides (RP=Se) n can be used as phosphorus source and treated the phosphinidene selenide dimer (DmpP=Se) 2 (Dmp = 2,6‐dimesitylphenyl) with 4 equivalents of 1,3,4,5‐tetramethylimidazol‐2‐ylidene ( 2 ) or 1,3‐diisopropyl‐4,5‐dimethylimidazol‐2‐ylidene ( 4 ) to afford the NHC=PR adducts 2· P(Dmp) ( δ 31 P = –76.7) and 4· P(Dmp) ( δ 31 P = –75.0) in 44 and 66 % yield, respectively, together with the corresponding selenoureas (Scheme ) . The phosphinidene selenide trimer (DmpP=Se) 3 works equally well as phosphinidene synthon and yields 2· P(Dmp).…”

“…Ragogna and co‐workers reacted 4· P(Dmp) ( δ 31 P = –75.0) with the strongly Lewis acidic B(C 6 F 5 ) 3 in THF, which results in controlled ring‐opening of THF affording product 27 ( δ 31 P = –24.7; Scheme ) …”

“…Ragogna and co‐workers explored the coordination of (tht)AuCl to 4· P(Dmp) ( δ 31 P = –75.0). This reaction resulted in the formation of bis‐gold(I) chloride complex 63 ( δ 31 P = –41.9; Scheme ) which akin to 59c is monomeric in the solid state …”

Main Group Multiple Bonds for Bond Activations and Catalysis

“…Further reactivity of 38 showed that it could be used to access mixed main group element rings (Compounds 42 and 43 , Scheme 9). [73] …”

Synthesis and Structures of RhI and IrI Complexes Supported by N‐Heterocyclic Carbene‐Phosphinidene Adducts

“…N‐heterocyclic carbene‐phosphinidene adducts have found numerous applications in diverse fields such as the frustrated Lewis acid‐base pair chemistry, for example in the activation and ring‐opening of THF, and as new ligands in coordination chemistry . Furthermore, Grützmacher et al reported that treatment of the Lewis adduct of a zinc(II) complex such as [{(IMe)PPh}(ZnCl 2 (thf)]] 2 with a series of organic acceptors phenanthrene‐9,10‐quinone, diphenylketene, and trans ‐chalocone yielded the corresponding organophosphorus compounds by transfer and insertion of the PPh moiety .…”