Reactions of the Disilane Me₃SiSiCl₃ with P‐Chlorophosphaalkenes: Transient and Persistent Per‐Silylated Phosphaalkenes

Abstract

Reactions of P-chlorophosphaalkenes (RMe 2 Si) 2 C=PCl (1a: R = Me; 1b: R = Ph) with the disilane Me 3 SiSiCl 3 (5) furnish diphosphenes (Cl 3 Si)(RMe 2 Si) 2 C-P=P-C(SiCl 3 )(SiMe 2 R) 2 (4a: R = Me; 4b: R = Ph) by Me 3 SiCl elimination. The structure of the new compound 4b was confirmed by X-ray diffraction; it displays crystallographic inversion symmetry. Monitoring the reactions with 31 P-and 29 Si-NMR spectroscopy detected P-(trichlorosilyl)phosphaalkenes (RMe 2 Si) 2 C=PSiCl 3 (2a, R = Me; 2b, R = Ph) as the primary intermediates from reductive P-silylation of 4a, 4b, and P- [(trichlorosilyl)phosphanyl]phosphaalkenes (RMe 2 Si) 2 C=P-P(SiCl 3 )C(SiCl 3 )(SiMe 2 R) 2 (3a: R = Me; 3b: R = Ph) as unsymmetric dimerisation products that

Dichlorosilylene Transfer to a P‐Fluorophosphaalkene: The Route to a C‐Dichlorofluorosilyl‐Functionalized Dialkyldiphosphene

“…Several attempts in further experiments to reproduce the detection of the “ δ P = –169.4 ppm species” failed. There was, however, no hint in the NMR spectra for the initially expected species (Me 3 Si) 2 C=PSiCl 2 F ( 7a ), which would be analogous to previously observed compounds (RMe 2 Si) 2 C=PSiCl 3 (R = Me, i Pr, Ph) from the above‐mentioned reactions of P ‐chlorophosphaalkenes (type II in Scheme ). 31 P NMR spectra of the reaction mixtures confirm that the species exhibiting the two AMXY patterns ( 8a , 8b ) are consumed very slowly at room temperature in favor of the AA′XX′ pattern of the final product 6 .…”

“…For the intended SiCl 2 transfer to the P ‐fluorophosphaalkene (Me 3 Si) 2 C=PF ( 1 ), the reagents Me 3 GeSiCl 3 and Me 3 SiSiCl 3 , were chosen because of their higher reactivity and better selectivity, compared with Si 2 Cl 6 .…”

“…By using the unsymmetric disilane Me 3 SiSiCl 3 and P ‐chlorophosphaalkenes with different C ‐silyl group patterns (C‐SiPhMe 2 , C‐Si i PrMe 2 ) as starting materials, the connectivities of the non‐isolable type II P ‐(trichlorosilyl)phosphaalkenes and type III P ‐[(trichlorosilyl)phosphanyl]phosphaalkenes were confirmed unequivocally from reaction mixtures with the help of 29 Si and 31 P NMR spectroscopic data . Explaining the mechanisms of the reaction steps leading from P ‐chlorophosphaalkenes and Me 3 SiSiCl 3 to compounds of types II (monomer) and III (unsymmetric dimer), however, is still a challenge.…”

“…Intermediates and products identified by NMR spectroscopy from reactions of 1,1,1‐trichloro‐2,2,2‐trimethyldisilane with P ‐chlorophosphaalkenes …”

“…The first part of our investigation reports synthetic experiments by using SiCl 2 transfer reagents Me 3 MSiCl 3 (M = Si, Ge) for reactions with 1 (i), and the second section (ii) presents quantum chemical calculations on the formation of type III ‐like unsymmetric dimers (Me 3 Si) 2 C=PP[C(SiCl 2 X)(SiMe 3 ) 2 ]SiCl 2 X (X = F, Cl), which were detected by NMR spectroscopy in the course of the SiCl 2 transfer reactions from Me 3 MSiCl 3 (M = Si, Ge) to 1 (this work) and to (Me 3 Si) 2 C=PCl ( 1′ ) , …”