Robert Knebl

From 1,3-Diphosphacyclobutadiene to 1,3,5-triphosphabenzene

Abstract Alkyl- and aryldiaminodifluorophosphoranes 1 can easily be obtained by fluorination of alkyl- and aryldiaminophosphanes with sulfur tetrafluoride, SF4 1. Peralkylated alkyldiaminodifluorophosphoranes react with one mole of n-butyllithium to form P-fluoro-ylides, a class of compounds which had not been described previously 2 . Methylbis(dimethylamino)difluorophosphorane 2, e.g., reacts with butyllithium to give methylenebis(dimethylamino)fluorophosphorane 3, a colorless liquid, b.p. 42 °C (10 Torr)2: For P-chloro-ylides such as (t-C4H9)2PCI=CHSi(CH3)3, the chloro ligand is substituted by the alkyl group upon reaction with methyl-or n-butyllithium 3,4; however, P-fluoro-ylides behave in a different way. If 2 is reacted with two moles of butyllithium, the main product is the crystalline, colorless 1,1,3,3-tetrakis(dimethylamino)-1Δ5, 3Δ5−diphosphete or 1,1,3,3-tetrakis(dimethylamino)-1Δ5, 3Δ5−diphosphacyclobutadiene 4 (chemical shift δ (P) = 48.9 ppm)5.

Polarity and polarisability of 3,3-dimethyl-1-phosphabutyne

Abstract The progress attained in the field of onecoordinated phosphorus compounds was summerised recently in review (Usp. Chim., 1985, v. 54, p. 418). Formerly we have been analysed (Izv.Akad.Nauk USSR, Ser.chim., 1984, p. 415) the polarity of P°C triple bond in phosphaalkynes on the grounds of literary date on dipole moments defined by microwave spectroscopy. In this work the dipole moment of 3,3-dimethyl-1-phosphabutyne (I) was determined in cyclohexane solution: μexp.=1,24±0,05D, α=1,250, γ=0,078, Po=31,876 cm3. Analysis of all known up to date experimental date on polarity of phosphaalkynes brings us to the conclusion about small polarity of P°C triple bond and slight sensitivity of this value (0,7±0,2D towards carbon atom) to vareing of substituent at Csp-atom. We can only note slight tendency of the increasing m(P[tbnd]C) in the phosphaalkynes RC[dbnd]P (R=H, CH3, F, CH=CH2, CN, tBu) with the growth of -I - effect of substituent R.