CPh₃ as a functional group in P-heterocyclic chemistry: elimination of HCPh₃ in the reaction of P-CPh₃ substituted Li/Cl phosphinidenoid complexes with Ph₂CO

Abstract

P-CPh3 substituted oxaphosphirane complexes 3 were prepared using Li/Cl phosphinidenoid complexes 2 (M = Cr, Mo, W) and benzaldehyde. Employing 2 and benzophenone resulted in the formation of oxaphospholane complexes 4 and 5, the former bearing a benzo[c]-1,2-oxaphospholane and the latter a novel pentacyclic P-ligand. According to DFT studies the latter P-heterocycle arises from formal dimerization of a transient benzofused 2-phosphafurane complex 8, one of the fragments undergoing water-catalyzed [1,3]H shift (4) and the other (11) formed via elimination of HCPh3.

Synthesis of the First Oxaphosphirane Iron Complexes

“…Since the first oxaphosphirane complex formation by formal cheletropic cycloaddition of a carbonyl component with a P 1 fragment coming from a in situ generated phosphinidene complex, an initial nucleophilic attack from O to the electrophilic phosphinidene P atom was assumed. [11] Only very recently, this was computationally proven [12] which was previously shown only for the reaction with imines. [13] However, the most recent and syntheticcally very useful "similar" reaction of Li/Cl phosphinidenoid complexes with carbonyl compounds has never been computationally explored, neither for the "classical" zerovalent group 6 pentacarbonyl complexes nor the herein reported reaction with tetracarbonyliron(0) fragments.…”

“…Therefore, we investigated the reaction of 3 a with acetonitrile to test our ring-expansion protocol. [11] Complex 3 a was treated with HOTf in CH 2 Cl 2 at À 30°C in the presence of acetonitrile (Scheme 4). After warming up to ambient temperature and, again cooling down to À 30°C, NEt 3 was then added, warmed up and filtered to yield the 1,3,4-oxazaphosphol-2-ene complex 12 in 42 % yield.…”

Cycloaddition of P−C Single Bonds: Stereoselective Formation of Benzo‐1,3,6,2‐trioxaphosphepine Complexes via a Ditopic van der Waals Complex

“…This can be viewed as resulting from ditopic reciprocal interaction through a) formation of a hydrogen bond (HB) with one of the C=O oxygen atoms and b) interaction of the electron‐rich metal carbonyl ligand with the electron‐deficient cyclic π‐system (Scheme ). According to previous calculations on C‐phenyl‐substituted model systems, the P−C bond cleavage is expected to be less endergonic and have a lower energy barrier in real systems (Δ E =28.90 kcal mol −1 ; Δ E ≠ =37.72 kcal mol −1 ) . Furthermore, a lower‐energy TS structure (Δ E ≠ =38.34 kcal mol −1 ) was found for the direct transformation of 1 e into 3 e in the presence of TOB (ii).…”

Coordination of N2and Other Small Molecules to the Phosphorus Centre of RPW(CO)5: A Theoretical Study on the Janus Facets of the Stabilization/Activation Problem

“…Local correlation schemes of type LPNO (local pair natural orbital) for high level single reference methods, such as CEPA (coupled electron‐pair approximation)—here the slightly modified NCEPA/1 version implemented in ORCA was used—were used for the case of nitrene ligand and for open‐shell bond fragmentation products, as DLPNO‐CCSD(T) is not implemented for unrestricted formalisms. Very close values between these two levels has been systematically reported for close‐shell systems with rmsd (root mean square deviation) typically below 0.2 kcal mol −1 ,. All electronic properties including bond strength related parameters were computed at the B3LYP/def2‐TZVPP level.…”