(Iminomethylidene)phosphines (RP:C:NR)

Abstract

There has been much recent interest in compounds incorporating P=C2,3 and p=p4 double bonds. Furthermore, the stable (2,2-dimethylpropylidyne)phosphine, (CH 3 hCC=P, featuring a PC triple bond has been prepared. 5 However, previous attempts to isolate cumulenes possessing a two-coordinate phosphorus atom, RP=C=X, have failed,2,3,6 except in a single case, the preparation of the stable and sterically protected (CH 3 hCP=C=NC We now wish to report a general method of preparation of unstable (iminomethylidene)phosphines (monophosphorus analogues of carbodiimides), their direct observation by IR and mass spectrometry, and their initial chemical reactions.The required starting materials, (iminomethyl)phosphines 1, exist in equilibrium with carbamoylphosphines [(CH 3 hSiP(R)-CON(Ph)Si(CH 3 hl and smaller amounts of alkylidenephosphines RP=C(OSi(CH 3 h)N(Ph)Si(CH 3 h 8 In analogy with the reaction used in the preparation of (CH3)3CO=P,5 the compounds 1 could be expected to eliminate hexamethyldisiloxane and thus give rise to the desired (iminomethylidene)phosphines, RP= C=NPh (Scheme I). (2) Appel, R.; Knoll, F.; Ruppert, L Angew. Chern. 1981,93,771; Angew. Chern., Int. Ed. Engl. 1981,20,731. Chern. Soc. 1981, 103,4587. Cowley, A. H.;Newman, T. H.; Pakulski, M. Ibid. 1982, 104, 5820. Bertrand, G.;Couret, c.;Escudie, J.;Majid, S.; Majoral, J.-P. Tetrahedron Lett. 1982, 23, 3567. Couret

Heavy Allenes and Cumulenes ECE‘ and ECCE‘ (E = P, As, Si, Ge, Sn; E‘ = C, N, P, As, O, S)

“…When the steric hindrance is not important enough, the main reaction of phosphaazaallene is a very easy head-to-tail dimerization by the PdC double bonds 85,86,95 (eq 27, Schemes 12 and 13). This is well understood from the large difference in the HOMO-LUMO energy separation between the PdC and CdN bonds, which induces a strong stabilizing interaction when the two CdP double bonds approach each other.…”

Flash Vacuum Pyrolysis: Techniques and Reactions

“…(31)]. [127] Ethenedithione S=C=C=S was generated from three different precursors by FVP (Scheme 12). [128] The reactions were monitored by on-line mass spectrometry (Figure 7), and the products were isolated in Ar matrix at 12 K for IR and UV spectroscopy using the cryostat in Figure 5.…”

Flash‐Vakuumpyrolyse – Techniken und Reaktionen

“…(31)]. [127] Ethendithion, S = C = C = S, wurde durch FVP aus drei verschiedenen Ausgangsstoffen generiert (Schema 12). [128] Die Reaktionen wurden durch Online-Massenspektrometrie verfolgt (Abbildung 7) und die Produkte in einer Ar-Matrix bei 12 Ku nter Einsatz des Kryostaten von Abbildung 5z ur IRund UV-spektroskopischen Charakterisierung isoliert.…”