Reactions of Li/Cl Phosphinidenoid Complexes with 1,3,4,5‐Tetramethylimidazol‐2‐ylidene: A New Route to N‐Heterocyclic Carbene Adducts of Terminal Phosphin­idene Complexes and an Unprecedented Transformation of an Oxaphosphirane Complex

Abstract

Abstract:The reaction of Li/Cl phosphinidenoid tungsten(0) complex 2 [R = CH(SiMe 3 ) 2 ] with 1,3,4,5-tetramethylimidazol-2-ylidene (3) yielded the zwitterionic phosphaalkene complex 4. A comparative study on chloro-(5) or dichloro(organo)phosphane complexes 1 [R = CH(SiMe 3 ) 2 ] and NHC 3 revealed the formation of 4 at ambient temperature. First evidence for the forma-

Recent Advances in Imidazoliumyl‐Substituted Phosphorus Compounds

“…Quantum chemical calculations resolved a banana‐shaped ELF (electron localization function) isosurface at the P atom, indicating the presence of two lone pairs of electrons. The isolation of the monometallic and bimetallic complexes 10 – 14 additionally supports their findings …”

Transition‐Metal Carbonyl Complexes and Electron‐Donating Properties of N‐Heterocyclic‐Carbene–Phosphinidene Adducts

“…In all cases, the formation of pentacarbonyl complexes is confirmed, and they display slightly distorted octahedral geometries around the metal atoms. Similarly to those of other monometallic carbene–phosphinidene complexes,, , the phosphorus atoms reside in rather acute trigonal‐pyramidal environments, as indicated by angle sums of 329.4, 341.8, and 330.0° in 4b , 4c , and 5b , respectively. The P–M–C4 angles involving the axial carbonyl group are close to linearity for the parent phosphinidene complexes 4a and 5a [175.53(17) and 175.63(9)°, respectively], whereas a stronger deviation is observed for the sterically more congested complexes [170.24(10)° in 4b , 163.39(6)° in 4c , and 170.45(4)° in 5b ].…”

“…These results indicate that metal complexation of the carbene–phosphinidene species 1 leads to a stronger polarization of the carbon–phosphorus double bond, as illustrated by the canonical form B (Scheme ). In addition, a significant spreading of electron density over the W(CO) 5 moiety can be proposed on the basis of theoretical calculations . Notably, the coupling constants 1 J ( 31 P, 183 W) of complexes 4 are smaller than those established for [(R 3 P)W(CO) 5 ] complexes (e.g., 1 J P,W = 244 Hz for R = Ph) and increase in the order 4a < 4b < 4c (Table ).…”

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

“…Thus, addition of one equivalent of [W(CO) 5 (THF)] to 5· PH afforded monometallic 70 , which upon addition of an excess of [W(CO) 5 (THF)] led to a mixture of 70 and bimetallic 71 that was spectroscopically characterized (Scheme ) . Interestingly, these carbonyl complexes mimic carbene adducts of the transient electrophilic phosphinidenes [RP=M(CO) 5 ], such as [{ 2· PR}W(CO) 5 ] [R = CH(SiMe 3 ) 2 ] that was prepared by Streubel and co‐workers …”