Cyclic organophosphorus compounds—II the infrared spectra of some 1,3,2-Dioxaphosphorinanes

The IR spectra of 47 1,3,2-dioxaphosphorinanes, mostly new compounds, have been recorded and discussed. Assignments have been made to P=O, P---O---C (alkyl and aryl), P=S and P---N stretching motions. In addition,it is suggested tentatively that multiple bands found at around 1000 to 1050 cm⁻¹ and at around 1150 to 1200 cm⁻¹ may be due to ring P---O---(C) vibrations.     

Cyclic organophosphorus compounds. XVIII—the mass spectroscopy of some 2-amino-1,3,2-dioxaphosphorinans,cyclic phosphorodiamidates and phosphorodiamidothionates

Stepwise replacement of O in 1,3-dioxa-2-phospha(V)-cyclohexanes (or related ring systems) by NR (R=H or Me) leads to an increase in the stability of the hetero-ring ions produced under electron impact conditions. In the case of the 2-phenoxy derivatives, there is also an increased abundance of [M? PhO]⁺ or [M? PhOH]⁺ ions, and, for the 2-sulphides, a reduction in the abundance of [M-S]^+˙ and [M-SH]⁺ ions, with a concurrent increase in that of [M-PhS]⁺ ions. Such trends have been correlated with ultraviolet photoelectron spectral data on a qualitative basis.     

The mass spectra of some 1,3,2-oxazaborolidines

Low resolution mass spectra of a series of alkylphenyl-1,3,2-oxazaborolidines are reported. The characteristic fragmentations are shown to be an aid to the elucidation of the substituents in the 1,3,2-oxazaborolidine ring by means of a ‘substituent shift’ technique.     

The mass spectra of some 1,3,2-oxazaphospholanes

The mass spectra of six 1,3,2-oxazaphospholanes have been obtained. The compounds studied give strong m/e=M lines; the relative stability of the molecular ion correlates with the structure of the molecule. During the process of dissociative ionization, cleavage of the C-C and the P-O bonds in the ring takes place, with the molecular ion losing a R'CHO molecule. It has been shown that the molecule of an olefin is formed from the molecular ion mainly through an alkoxy group. A probable process of dissociative ionization is the loss by the molecular ion of an alkoxy group or, in the case of the 2-chloro derivative, the loss of a Cl atom.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 894–897, July, 1973.     

Rotational isomerism: XVII—solvent effects on the NMR spectra and rotamer energies of some tetrahaloethanes

The NMR spectra of 1,1-dichloro-2,2-difluoroethane ( 1 ), 1,1-dibromo-2,2-difluoroethane ( 2 ), meso and dl 1,2-dichloro-1,2-difluoroethane ( 3 ) and 1,1,2,2-tetrachloroethane ( 4 ) have been analysed in a number of solvents. The ¹⁹F spectrum of 3 in L-bornyl acetate at 56·4 and 94·1 MHz allows an unambiguous identification of the meso and dl isomers. The spectra of the d and l isomers consist of two AA′XX′ spectra with a small chemical shift difference between the d and l forms, whilst that of the meso form is an apparent AA′XX′ spectrum at 56·4 MHz but an ABXX′ spectrum at 94·1 MHz, the ¹⁹F nuclei in this isomer being anisochronous in this solvent. The observed solvent and temperature dependence of the couplings of 1, 2 , meso 3 and 4 when combined with the calculated solvation energies, allow the determination of the rotamer energies and couplings in these molecules. The rotamer energy differences (E_g – E_t) in the liquid and vapour states are 0·6 and ?0·2 kcal/mol ( 1 ); 0·4 and ?0·5 kcal/mol ( 2 ); 0·9 and 0·2 kcal/mol meso ( 3 ) and ?0·1 and ?0·8 kcal/mol ( 4 ). The ³J(HH), ³J(HF) and ³J(FF) couplings for the distinct rotamers are considered together with those of similarly constituted molecules. The general agreement demonstrates that the solvation theory may be applied to multisubstituted ethanes without any basic modifications. The trans oriented HH couplings show a linear substituent electronegativity dependence, which differs appreciably from that obtained for disubstituted ethanes, however. The gauche couplings show the influence of dihedral angle variations as well as substituent electronegativity. The rotamer ³J(FF) couplings in meso 3 are ?38·2 Hz (J_t) and ?17·4 Hz (J_g).     

Doubly charged ion mass spectra of organophosphorus compounds

Doubly charged ion mass spectra have been obtained for 11 organophosphorus compounds. Methane has been used as a target gas to increase the probability of single electron transfer collisions in the first field-free region of an Hitachi RMU-7L mass spectrometer. In general, the spectra of organophosphorus compounds do not exhibit molecular ions but are dominated by fragment ions, many of which must be formed by rearrangement processes. A geometry-optimized self-consistent field molecular orbital method has been employed to compute energies and structural parameters for prominent ions. In addition, a diabatic curve crossing model has been used to examine the single electron transfer reactions responsible for intense ions in the doubly charged ion mass spectra. Appearance energies measured for ions prominent in the 2E spectra of organophosphorus compounds have ranged from 23 to 38 eV.     

Hydride migration in the mass spectra of some 2-phenyl-1,3,2-dioxsilacycloalkanes

The mass spectra of a series of 2-phenyl-1,3,2-dioxasilacycloaklanes all contain a peak at $\text{m}\text{e}$ P–78, which we suggest arises from hydride migration from the ring.     

The mass spectra of some pyrazole compounds

The mass spectra of ten pyrazole compounds have been determined. Fragmentation schemes have been derived by means of the metastable defocusing method. The predominant process is cleavage of the nitrogen-nitrogen bond resulting in expulsion of HCN. The process second in prominence is the loss of a nitrogen molecule after initial removal of a hydrogen radical or a substituent, giving the species [C₃H₂R]⁺, probably a cyclopropenyl ion. In general, the fragmentation pattern is strongly influenced by the substituent.     

On the mass spectra of some alkyl digermanium compounds

This paper reports the monoisotopic mass spectra of the compounds (CH₃)Ge? Ge(CH₃)₃,(C₂H₅)₃Ge? Ge(C₂H₅)₃ and (CH₃)₃Ge? Ge(C₂H₅)₃. With the aid of metastable ion transitons and appearance potentials the fragmentation patterns can be given. The dominant reactions are explained in terms of the valence of the metal atom. According to the valence rule the possibility of forming an ion in which two germanium atoms are bonded to five other groups (alkyl or hydrogen) determines greatly the spectra, while successive elimination of the methyl groups appears to be difficult and elimination of the ethyl groups is a predominant process.     

Pyrones: V—The mass spectra and fragmentation mechanisms of some 3(5)-methoxy-4-pyrones

The mass spectra of methyl kojate (2-hydroxymethyl-5-methoxy-4H-pyran-4-one), two deuterated analogues and 14 related 3(5)-methoxy-4-pyrones have been studied. These compounds fragment according to a common mechanism, initiated by primary rearrangement of the molecular ion(s). Guidelines which indicate the presence of 3(5)-methoxy-4-pyrones and allow structural determinations to be made from their mass spectra are presented. For the majority of substituents studied, the nature of the substituent has no major effect upon the fragmentation pattern; the cyano group does. The hydroxy counterparts of the above compounds are readily converted for analysis by simple methylation.     

Negative ion mass spectrometry—I: The spectra of some stabilised alkylidenetriphenyl-phosphoranes

The 70 eV negative ion mass spectra of a series of phosphoranes exhibit significant peaks for ions resulting from skeletal rearrangements. The primary fragmentation reactions of the molecular anions, which involve reduction of the phosphorus from the penta- to the ter-valent state, have been rationalised in terms of the relative stabilities of the products formed. The processes occurring are in some cases analogous to and in other cases complementary to, those previously observed in the positive ion spectra of similar compounds.     

The mass spectra of some chlorinated pesticidal compounds

The mass spectra of nine bridged polycyclic chlorinated pesticidal compounds have been investigated, and fragmentation modes to account for the more abundant ions are postulated. The principal features of the spectra are ions corresponding to a set of retro-Diels-Alder decompositions, ions resulting from successive losses of Cl, HCl, or both, ions produced by combinations of a retro-Diels-Alder process with a preliminary or subsequent loss of Cl or HCl, and ions whose processes of formation more specifically involve the epoxide group.     

The elimination of metal(I) hydride in the mass spectra of some metal(II) compounds

Metal(I) hydrides are eliminated as neutral species in the electron impact ionization mass spectra of copper(II) and palladium(II) complexes of ethylene-N,N′-3-benzoylprop-2-en-2-amine. Deuterium labelling shows that the hydrogen atom of the metal(I) hydride is derived predominantly from the ethylene bridge both for ion source reactions and for metastable ion transitions. Evidence supporting the proposed rationalization for elimination of metal(I) hydride is provided by the observation of an analogous reaction in the mass spectrum of (ethylene-N,N′-salicylaldiminato)copper(II). The mass spectrum of ethylene-d₄-N,N′-3-benzoylprop-2-en-2-amine shows an unusual rearrangement to give [C₇H₅D₂]⁺ ions involving a formal phenyl-to-methylene transfer.     

The mass spectra of some chlorinated aromatic pesticidal compounds

Mass spectral studies of some chlorinated aromatic pesticidal compounds are reported. The compounds studied include substituted diphenyl derivatives of methane, ethene and methanol. The diphenylmethanes are characterized by a relatively intense peak at m/e 165. Comparison of their low voltage spectra with 9-dichloromethylfluorene indicates that this ion has a fluorenyl ion structure. The structure of the base peak (m/e 246) of the diphenylethenes was investigated by comparing competitive metastable transitions with 9-dichloromethylenefluorene and utilizing defocusing metastables. Additional studies of model compounds suggest that the m/e 246 ion is very complex and is probably comprised of a number of structures. The mass spectra of the diphenylmethanols are significantly different from the other two groups. The hydroxyl group markedly affects the fragmentation process for these compounds; the characteristic peak is presumably the chlorobenzoyl ion and is probably precursor for other fragment ions. Mass spectral correlations of pesticidal compounds of similar structure are needed to obtain enough background to facilitate interpretation of the mass spectra of their metabolites. Furthermore, such studies make feasible the identification of characteristic product ions formed by rearrangement processes during ionization of organic molecules in the gas phase. This information can be a nucleus for correlating the other significant mass spectral data of an unknown compound. Intensive studies of carbamates,¹ organophosphorus² and bridged polycyclic chlorinated pesticidal³ compounds were invaluable in identifying metabolites of the aforementioned pesticides.^4,5,6 The compounds in this Work are chlorinated aromatic pesticidal compounds which consist of a diphenylemthane, a diphenylethylene, or a diphenylmethanol structure. The compounds p,?-DDE were briefly discussed by Jorg, Houriet and Spiteller.⁷ The compounds examined are listed in Table 1. Treatment of data. The mass spectra of the pesticides are presented as bar graphs in Figs 1 to 12 It a metastable peak is observed, the metastable transition is indicated by m^* on the figures and also by (m^*) when confirmed or identified using the defocusing technique.⁸ Since the relative abundances of the metastable peaks for these compounds are very small (<0.1%) on special effort was made to establish their presence unless they wre pertinent.     

Electron impact mass spectra of 5,5-bis(carboethoxy)-1,3-dioxanes

Electron impact-induced fragmentations of 2-substituted 5,5-bis(carboethoxy)-l,3-dioxanes were studied by exact mass measurements and metastable ion analysis. The substituent R on C(2) of the heterocyclic ring has little influence on the principal cleavage reactions. Elimination of CH₂O/CO and C₂H₄O/C₂H₄/C₂H₅OH are common fragmentations for ions containing the 1,3-dioxane moiety or the OC₂H₅ group, respectively. The abundant ions at m/z 173 and 127 serve as structural probes for the class of compounds studied. Primary fragmentations implying the ester function are of little importance.     

Organoboron compounds: XXVI. A mass spectral study of some 2-phenyl-1,3,2-diazaboracycloalkanes

The mass spectra of the 2-phenyl-1,3,2-diazaboracycloalkanes contain peaks at m/e 91, 89, 65 and 63 which we assign to the tropylium, boratropylium, cyclopentadienyl and boracyclopentadienyl ions.