ChemInform Abstract: ELECTROPHILIC SUBSTITUTION AT THE TWO‐COORDINATE PHOSPHORUS ATOM. P‐SILYL‐, P‐GERMYL‐, AND P‐STANNYL‐SUBSTITUTED METHYLENEPHOSPHINES

Abstract

Die Reaktion des Phosphins (I) mit Trialkyl‐chlor‐silanen (II) verläuft umkehrbar.

Phosphaalkenes with Inverse Electron Density

“…Treatment of 8b with equimolar amounts of Ph 3 GeCl and Ph 3 SnCl in benzene at 40°C irreversibly afforded Ph 3 GePϭC(NEt 2 ) 2 (25) and Ph 3 SnPϭC(NEt 2 ) 2 (26), respectively (Scheme 14). [23] The replacement of the silyl function in 8a by a di-tertbutylphosphanyl group with formation of tBu 2 PϪPϭ C(NMe 2 ) 2 (27) was effected with an equimolar amount of tBu 2 PCl in diethyl ether. [9b] Scheme 14.…”

“…Here the compound with the highest degree of shielding at phosphorus is Ph 3 SiPϭC(NMe 2 ) 2 (δ ϭ Ϫ85.1). [23] An increasing low-field shift as a function of X is observed as follows: 7d (X ϭ H; δ 31 P ϭ Ϫ62.6) Ͼ 8a (Me 3 Si; Ϫ47.1) Ͼ 23a [TpЈ(CO) 2 MoϵC; 62.3] Ͼ 7c (tBu; 91.9) Ͼ 29a [Cp*(CO) 2 Fe; 135.5]. Particularly interesting is the replacement of the hydrogen atom at phosphorus by functional groups, which are able to withdraw electron density from phosphorus by π-delocalization as observed in MeO 2 CPϭC(F)NMe 2 (43) (δ 31 P ϭ Ϫ23.4) [30] vs. (E,Z)-HPϭC(F)NMe 2 (39a) (δ 31 P ϭ Ϫ90.0 and Ϫ99.9) [29] or in (Me 2 N)CϭPϪC(S)SSiMe 3 (32) (δ 31 P ϭ 145) [21] vs. 7d.…”

Phosphaalkenes with Inverse Electron Density

“…Bis(amino)methylene(trimethylsilyl)phosphane 8a underwent transsilylation when treated with equimolar amounts of chlorotriphenylsilane in benzene at 20°C for 3 h. [23] In contrast to this, the reactions of the phosphaalkenes with trialkylchlorosilanes were reversible as indicated by the action of (Et 2 N) 2 CϭPSiMe 3 (8b) with 1.2 equiv. of Me 2 Et-SiCl at 20°C, which led to an 1:2 equilibrium mixture of starting material and (Et 2 N) 2 CϭPSiMe 2 Et.…”

“…of Me 2 Et-SiCl at 20°C, which led to an 1:2 equilibrium mixture of starting material and (Et 2 N) 2 CϭPSiMe 2 Et. [23] The replacement of the silyl function in 8a by a di-tertbutylphosphanyl group with formation of tBu 2 PϪPϭ C(NMe 2 ) 2 (27) was effected with an equimolar amount of tBu 2 PCl in diethyl ether. [23] The replacement of the silyl function in 8a by a di-tertbutylphosphanyl group with formation of tBu 2 PϪPϭ C(NMe 2 ) 2 (27) was effected with an equimolar amount of tBu 2 PCl in diethyl ether.…”

“…Ϫ85.1 [23] [Cp*(CO) 2 FeϪPϭC(NMe 2 ) 2 ] 29a 135.5 202.4 97.0 [25] (E)ϪMe 3 SiPϭC(Ph)NMe 2 14a 54.3 204.7 65.2 [16] (Z)ϪMe 3 SiPϭC(tBu)NMe 2 14b 68.7 219.7 94.1 [16] (E)ϪPhϪPϭC(Ph)N(Ph)SiMe 3 (E)-16a 144 205 50 [17] (Z)ϪPhϪPϭC(Ph)N(Ph)SiMe 3 (Z)-16a 225 193 47 [17] PhϪP a ϭC a ϪN(SiMe 3 )C(OSiMe 3 )(Ph)P b Ph(C a ϪP b ) 18 112.7 197.3 60.6 [18] PhPϭC a N a (Me)…”