The mass spectrum and the ion molecule reactions of phosphirane and of mixtures of phosphirane with NH3 , NH2D, NHD2 and ND3 have been studied by ion cyclotron resonance spectrometry. Almost all important product ions are formed by PH-group transfer reactions, where ethene is generated as the neutral particle. Only two of the more abundant ions, the protonated molecule, H2P(CH2)2+ and the ion m/e=63, P2H+, are formed via other reaction pathways. Secondary, tertiary and quarternary product ions with the general formula R(PH)n+ (R: phosphirane fragment, n-1, 2, 3) have been detected.
The molecular ion is proved to have a cyclic structure. Two possible structures of the product ions with two and three phosphorus atoms are discussed: a structure with an open phosphorus chain, leaving the phosphirane ring intact and a ring extended structure, produced by a ring extension reaction of the PH-group.
Several rate constants of the ion molecule reactions of the phosphirane molecular ion are given.
The ion-molecule reactions of thiothionylfluoride have been studied by ion cyclotron resonance spectrometry. The major secondary ions are S2F3+ , S3F+ , and S3F2+. In a consecutive reaction of S3F2+ the tertiary ion S4F2+ is formed. The rate constant of the IMR with the greatest yield S2F2+ + SSF2 → S3F2+ + SF was estimated to k = 2 · 10-9 cm 3 molecule -1 sec -1 . The results were compared with the mass spectrum of thiothionylfluoride. They permit conclusions on chemical reactions of lower sulphurfluorides.
Nuclear magnetic resonance measurements were carried out on neutron activated 20F(T1/2=11s) nuclei in a single crystal of KZnF3. The quadrupolar splitted NMR spectrum, detected via the 20F β-radiation asymmetry, could be observed using a radio frequency modulation technique. The quadrupole coupling constant was determined to e2 q Q/h= + (12.0 ± 1.5) MHz at room temperature. The sign of e2 q Q was obtained from a simultaneous γ-ray anisotropy measurement on the succeeding 20Ne transition. Utilising a calculated field gradient of the fluorine atom, an fQ = 4.6% is determined. This value is compared with literature data of similar compounds.
The mass spectra and the ion molecule reactions of methylphosphine, dimethylphosphine and dimethyldeuterophosphine have been studied by ion cyclotron resonance spectrometry. About 50 ion molecule reaction are observed for each compound. The product ions can be classified as ions with two phosphorus atoms: P2R5+, P2R3+, P2R2+ and P2R+ (R = CH3 or H), as phosphonium and phosphinium ions and ions resulting from collision dissociations and charge exchange reactions. Tertiary ions with three phosphorus atoms like CH3P3H2+ (from CH3PH2) and (CH3)4P3H2 (from (CH3)2PH) have also been detected. The mechanisms of the ion molecule reactions, rearrangements, P -H- and C-H-reactivities and product ion structures are discussed, using in the case of dimethylphosphine the results obtained with the deuterated compound. Rate constants of formation of the more abundant product ions from the molecular ion and the CH3P+ ion, both odd electron particles, have been determined. The reactions with dimethylphosphine have much smaller rate constants than the reactions with methylphosphine.
The gas phase ion chemistry of the simplest known phosphorus ylide, trimethylmethylenephosphorane, has been studied in the mass range m/e=2 - 186 and the pressure range 10-7-10-4 Torr. The most abundant product ion, m/e = 104, (CH3)2C2H5PCH2'+ is formed by a methylene group transfer reaction of the molecular ion. Almost all of the other product ions formed from the molecular ion can be subsumed under the general formula (CH3)3PCHPRn+ (R = H, CH3; n=1,2,3). The reactions indicate that the molecular ion has lost its ylide character almost completely. The protonated molecule is formed almost exclusively by a reaction of the fragment ion m/e = 75. This reaction and the CH3PH group transfer reaction indicate a cyclic structure (CH3) HP(CH2)2+ for this ion. A cyclic structure is also assumed for the ion m/e = 73, PC3H6+, which undergoes P and PH transfer reactions. The reactions of the ion m/e = 47 are consistent with the structure CH3PH+. The ICR and mass spectra are given, some metastable decompositions are discussed.
The low temperature IR stretching vibrations of difluorodisulfane (FSSF) and thiothionylfluoride (SSF2), in the solid phase and in a cyclohexane matrix, of the mixtures FSSF -SSF2, FSSF-OSF2 and SSF, -OSF2, and of solid difluorotrisulfane (FS3F) have been investigated. While SSF, forms no distinct oligomers, a dimer with absorption bands at 635 and 682 cm-1 has been detected in the case of FSSF. These differences between FSSF and SSF, are rationalized by the different S-F bond lengths. A structure of the FSSF dimer similar to that of the sulfur tetrafluoride dimer is proposed. The low temperature spectrum of FS3F shows 3 bands in the frequency range between 460 and 1000 cm-1: 590, 605 and 680 cm-1, due to associated molecules. FS3F decomposes on warming. The main decomposition products containing fluorine are FSSF and SSF2. Mechanisms for the rearrangement and decomposition of the three compounds studied are discussed.
The theoretical IR-frequencies of sulphurdifluoride are computed from force constants, which are evaluated by means of molecules with S-F-bonds: ν1 = 795 ± 10cm-1, ν2 = 430± 5cm-1, ν3= 830 ± 10cm-1.