A Persistent 1,2‐Dihydrophosphasilene Adduct

Abstract

The reaction of the arylchlorosilylene-NHC adduct ArSi(NHC)Cl [Ar=2,6-Trip2 -C6 H3 ; NHC=(MeC)2 (NMe)2 C] 1 with one molar equiv of LiPH2 (.) dme (dme=1,2-dimethoxyethane) affords the first 1,2-dihydrophosphasilene adduct 2 (ArSi(NHC)(H)PH). The latter is labile in solution and can undergo head-to-tail dimerization to give [ArSi(H)PH]2 3 and "free" NHC. Further stabilization of 2 by complexation with {W(CO)5 } affords the isolable 1,2-dihydrophosphasilene-tungsten complex 4 [ArSi(NHC)(H)P(H)W(CO)5 ]. Additionally, the new 1-silyl-2-hydrophosphasilene ArSi(NHC)(H)PSiMe3 5 could be synthesized and structurally characterized. DFT studies confirmed that the SiP bond in 2 and 4 is mostly zwitterionic with drastically decreased double-bond character.

Advances in Phosphasilene Chemistry

“…Selected structural parameters of 4 , calculated at different theory levels, are shown in Figure . The calculated Wiberg bond index (WBI) for the Si=P bond in H 2 Si=PH was found to be 1.97, and the bond dissociation energy (BDE) is 75.0 kcal mol −1[31] at the B97‐D/6‐31G(d) level of theory. The π‐bond energy, D π (Si=P), of 4 (36.6/35.9 kcal mol −1 ) is higher than that of the parent disilene H 2 Si=SiH 2 (27.3/25.6 kcal mol −1 ) and close to that of the parent silene H 2 Si=CH 2 (39.6/37.7 kcal mol −1 ) .…”

“… Calculated structural parameters of phospahsilenes 4 – 7 at different levels of theory, [a] B3LYP/6–31+G**; [b] HF/6‐31G*; [c] B97‐D/6‐31G(d).…”

Facile Access to Stable Silylium Ions Stabilized by N-Heterocyclic Imines

“…The difference in the steric bulk of the precursors 1 and 3 leads to different products based on the reaction kinetics. Figure 3 shows the energy profile along the reaction path calculated at the B97-D/6-31G(d) level of theory which has been successfully applied in low-valent silicon compounds [38][39][40][41][42][43][44][45][46][47]. The first step in the reaction is the abstraction of a Me group of a Me 3 Si moiety by the B(C 6 F 5 ) 3 (TS1 Dip ) with the associated energy of +18.9 kcal/mol for 2[MeB(C 6 F 5 ) 3 ] 2 .…”

S–H Bond Activation in Hydrogen Sulfide by NHC-Stabilized Silyliumylidene Ions

“…Also, we could demonstrate the recovery of silyliumylidene A from VIIIa-c by the treatment with AuI as well as chalcogen transfer reactions. dihydrophosphasilene reported by Driess and coworkers in 2015 [56,57] as well as the reaction towards diazoalkanes and azides presented by Filippou and coworkers [58] remain as the only reports regarding the reactivity of this species.…”

“…Subsequently, the mTer iPr -chlorosilylene was employed as the precursor for the preparation of a silylidyne complex Cp(CO) 2 Mo≡Si(mTer iPr ) [55]. The conversion of those chlorosilylenes with lithium diphenylphosphine and LiPH 2 to the corresponding phosphinosilylene and 1,2-dihydrophosphasilene reported by Driess and coworkers in 2015 [56,57] as well as the reaction towards diazoalkanes and azides presented by Filippou and coworkers [58] remain as the only reports regarding the reactivity of this species.…”