A detailed rotational analysis of the 1-fluorophosphaethene, CH2PF, microwave spectrum in the range 26.5–40.0 GHz has been made. The analysis yields A0 = 28482.29(6), B0 = 8890.31(1), and C0 = 6760.13(1) MHz. Transitions of the 13CH2PF isotopically substituted species have also been detected and a reliable structure has been determined: r(CP) = 1.644(5) Å, r(PF) = 1.598(5) Å, and ∠CPF = 104.16(20)°. The dipole moment components have been measured: μA = 1.355(4) and μB = 0.156(31) Debye.

The chlorinated phosphaethene, CH2PCl, which is an unstable molecule, has been detected by microwave spectroscopy when CH3PCl2 or Me2SiCH2PCl2 is pyrolyzed in flow systems. Six isotopic modifications, including all feasible singly substituted species, have been studied yielding sufficient data for a reliable structure determination to be carried out. Quadrupole and dipole moment data have also been obtained. For 12CH231P35Cl the spectroscopic parameters are A0 = 22 712.5(3.3) MHz, B0 = 4667.318(6) MHz, C0 = 3865.535(7) MHz, χAA = −41.04(1) MHz, χBB = 19.32(2) MHz, χCC = 21.72(2) MHz. The derived structural parameters are r(CP) = 1.660 ± 0.007, r(PCl) = 2.060 ± 0.003, r(CHc) = 1.090 ± 0.015, r(CHt) = 1.078 ± 0.005; ∠(CPCl) = 103.0 ± 0.7, ∠(HcCP) = 124.6 ± 0.3, ∠(HtCP) = 116.6 ± 0.6, ∠(HCH) = 118.8 ± 0.4.

A detailed assignment and accurate analysis of the R-band microwave spectrum of phosphaethene CH2PH, has been carried out and the rotational constants A0= 138 503·20(21), B0= 16 418·105(26), and C0= 14 649·084(28) were derived together with all five quartic centrifugal distortion coefficients; this simplest phospha-alkene has been obtained by pyrolysis of SiMe3CH2PH2(at 710 °C) as well as of (CH3)2PH and CH3PH2(at 1000°C), though less efficiently.

The microwave spectrum of the new linear triatomic molecule C-fluorophosphaethyne FCP which is produced when CF3PH2 vapor passes over solid KOH at room temperature and ca. 20 μmHg pressure has been studied. Transitions belonging to the two isotopic variants 19F12C31P and 19F13C31P have been analyzed and the resulting structural data are r(FC) = 1.285 ± 0.005 Å and r(CP) = 1.541 ± 0.005 Å. The study has yielded the following spectroscopic parameters for 19F12C31P: B0 = 5257.80 ± 0.03 MHz, α2 = −11.95 ± 0.05 MHz, q2 = 4.478 ± 0.002 MHz, and μ = 0.279 ± 0.001 Debye.

The conditions for the isolation of 1-phosphapropyne, CH3CP, recently detected by microwave spectroscopy in the products of the gas-phase pyrolysis of PEtCl2, have been studied by photoelectron spectroscopy. Although CH3CP is not the major product it can be trapped and separated from other reaction products under controlled conditions and subsequently revaporised. The He(I) photoelectron spectrum of CH3CP has been assigned and compared with that of FCP and HCP and the related nitrogen analogues.

The J = 4 ← 3 and J = 3 ← 2 rotational transitions of 1-phosphapropyne, CH3CP, between 26.5 and 40 GHz have been studied by microwave spectroscopy. The spectrum shows the characteristic vibration-rotation satellite patterns associated with a C3v symmetric rotor. Apart from the most abundant isotope variant, the species 12CD312C31P, 12CD2H12C31P, 12CH2D12C31P, 13CH312C31P, 12CH313C31P, 13CD312C31P, and 12CD313C31P have also been studied. For 12CH312C31P the rotational constants B0 = 4991.339 ± 0.003 MHz, DJ = 0.823 ± 0.092 kHz, DJK = 66.59 ± 0.18 kHz have been determined. From these data the following structural parameters have been derived: rs(CH) = 1.107 ± 0.001 Å, ∠s(HCC) = 110.30 ± 0.09°, rs(CC) = 1.465 ± 0.003 Å, r0(CP) = 1.544 ± 0.004 Å. The dipole moment has been determined as 1.499 ± 0.001 D by analysis of the Stark effect of the J = 3 ← 2, |K| = 1 line. The vibrational satellites (vs = 1, 2, and 3) have been studied and various vibration-rotation parameters derived.

AbstractDurch langsames Überleiten von Trifluormethylphosphin (I) über festes KOH bei Raumtemp. und einem Druck von etwa 30 "m Hg (40 cm lange Glasspirale mit l cm Durchmesser) wird je nach Fließgeschwindigkeit das Phosphaethen (II) oder ‐ethin (III) in guten Ausbb.

Diethylketomalonate (DEKM) reacts with triethylsilyl, tri-n-butylstannyl and tricyclohexylplumbyl radicals to give adduct radicals detectable by ESR. This is the first observation of the addition of a lead-centred radical to a carbonyl group. The hydrogen atom adduct of DEKM exhibits line broadening effects attributed to rotational isomerism of the hydroxyl group. The dynamics of this process have been determined.

The addition of lead-centred radicals to five α-dicarbonyl compounds has been investigated by e.s.r. In a number of cases satellite hyperfine lines from 207Pb have been detected. The structures of the adduct radicals are discussed in terms of their e.s.r. spectra; comparison is made with analogous adducts formed by other group 4B radicals.

Chemischer InformationsdienstVolume 7, Issue 44 Preparative Organic Chemistry ChemInform Abstract: THE DETECTION OF UNSTABLE MOLECULES BY MICROWAVE SPECTROSCOPY- PHOSPHA-ALKENES CF2 = PH, CH2 = PCL, AND CH2 = PH M. J. HOPKINSON, M. J. HOPKINSONSearch for more papers by this authorH. W. KROTO, H. W. KROTOSearch for more papers by this authorJ. F. NIXON, J. F. NIXONSearch for more papers by this authorN. P. C. SIMMONS, N. P. C. SIMMONSSearch for more papers by this author M. J. HOPKINSON, M. J. HOPKINSONSearch for more papers by this authorH. W. KROTO, H. W. KROTOSearch for more papers by this authorJ. F. NIXON, J. F. NIXONSearch for more papers by this authorN. P. C. SIMMONS, N. P. C. SIMMONSSearch for more papers by this author First published: November 2, 1976 https://doi.org/10.1002/chin.197644137Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume7, Issue44November 2, 1976 RelatedInformation

The reactive molecule 1-phosphapropyne, CH3CP, which is the phosphorus analogue of methylcyanide CH3CN, has been detected by microwave spectroscopy in the pyrolysis products of ethyldichlorophosphine CH3CH2PCl2. The J = 3 ← 2 and J = 4 ← 3 symmetric top transitions have been assigned and a value of B0 = 4991.339 ± 0.010 MHz obtained. These results indicate that alkyl substituted analogues of phospha-acetylene, HCP can be produced by the pyrolysis of the appropriately substituted dichlorophosphine.

ESR spectra have been obtained for the fluorenyl and indenyl radicals, and their isotropic proton hfcc have been compared with the predictions of semi-empirical MO calculations.