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EI fragmentation of trimethylphosphine sulfide (CH 3 ) 3 P(S)(1) is reported and discussed. [1] +. mainly retains the connectivity of the neutral molecule and no rearrangements to other long-lived isomeric forms occur. However, some [1] +. ions undergo a unimolecular reaction by a [1,3]-hydrogen shift from carbon to sulfur atom to produce the short-lived carbon centered ylide radical [(CH 3 ) 2 ( - CH 2 )P + -SH]. Further, isomerization of the molecular ion by an [1,2]-shift of a methyl group from phosphorus to sulfur is suggested which leads to [(CH 3 ) 2 P-SCH 3 ] +- . Compared to [1] +- the coordination number at phosphorus in the latter ion is reduced from four to three. Structures of fragment ions [C 2 ,H 6 ,P,S] + (m/z 93), [C 3 ,H 8 ,P] + (m/z 75) and [C 2 ,H 6 ,P] = (m/z 61) have been examined by collisional activation (CA) mass spectrometry. All the even-electron ions exist with a phosphonium structure as dimethylthioxophosphonium- [(CH 3 ) 2 P = S] + (m/z 93), dimethyl-methylenephosphonium-[(CH 3 ) 2 P = CH 2 ] + (m/z 75), and methyl-methylenephosphonium-ion [(CH 3 )HP = CH 2 ] + (m/z 61), respectively. The experimental findings are confirmed and complemented by the results of ab initio MO calculations.

Crystal structure analysis of (CO)5CrPH2COOH (a = 1338.2, b = 622.6, c = 1161.5 pm, β = 96,77°, P21/c, Z = 4, R = 0.0330) has shown the complex to be dimerized via hydrogen-bonds of the COOH group. Geometrical parameters of the hypothetical free ligand [H2PCOOH]2 were calculated using the HF/3-21 G*, HF/6-31G** and MP2-FU/6-31 G** basis sets. Bond lengths and bond angles of the calculated free ligand are similar to those derived from the crystal structure analysis of the coordinated ligand and are not significantly influenced by coordination and/or intermolecular interactions.

The preparation of lithiumphosphinoformates R2PCOOLi 1 (R = Ph, c-Hexyl, i-Pr, Et) and RHPCOOLi 2 (R = Ph, c-Hexyl) from R2PLi or RPHLi and CO2 is described. In the latter reaction RP(COOLi)2 3 and RPH2 are formed in addition to 2. In protic media 1–3 are rapidly decomposed with decarboxylation and formation of R2PH and RPH2, respectively. Reactions of 1 with McI, (MeO)2SO2, Me3SiCl and CS2 are similar to those of Ph2PCOONa and no significant influence of R was detected. With (MeO)2SO2 mixtures of 2 and 3 gave esters RHPCOOMe and RP(COOMe)2 while with Me3SiCl RHPCOOSiMe3 was obtained as the sole product. Ab initio MO calculations (GAUSSIAN 90 system of programs; HF/3-21G∗, HF/6-31G∗∗ and MP2/6-31G∗∗ basis sets) showed the phosphinoformic acid to be less stable than its decomposition products, from which it is separated by a high barrier of isomerization. Therefore the acid should be stable in the rarefied gas phase. Die Darstellung der Lithiumphosphinoformiate R2PCOOLi 1 (R = Ph, c-Hex, i-Pr, Et)...

An ab initio study was made of the radical anions of thioxophosphane (H-PS) and thiohydroxyphosphinidene (H-S-P). Geometries were optimized at the UHF/3-21G ∗ , UHF/6-31G ∗∗ , UHF/6-31++G ∗∗ and UMP2/6-31++G ∗∗ levels of theory. Furthermore, the transition state between [H-P-S] .− and [H-S-P] .− was determined. The calculations show that [H-P-S] .− is more stable than [H-S-P] .− , with a significant barrier to isomerization. The opposite order of stability for the corresponding cations has been found previously.

The dissociative ionization by electron impact (70 eV) of tetraphosphorus trisulfide, P4S3, yields [P3S]+ and [PZS]+0 ions whose structures have been investigated by means of Coliisionai Activation (CA) mass spectra. Using the technique of Neutralization-Reionization mass spectrometry (NRMS) it is shown that both ions can be reduced to the corresponding neutral molecules. Thus, triphosphorus sulfide and diphosphorus sulfide are viable molecules in the rarefied gas phase. The results of ab initio MO calculations were used to interpret the experimental findings. Tetrahedral (C3v) and triangular (C2v) structures are proposed for the [P,S]+ and [PZS]+0 ions respectively.

The dissociative ionization by electron impact (70 eV) of tetraphosphorus trisulfide, P4S3, yields [P3S]+ and [PZS]+0 ions whose structures have been investigated by means of Coliisionai Activation (CA) mass spectra. Using the technique of Neutralization-Reionization mass spectrometry (NRMS) it is shown that both ions can be reduced to the corresponding neutral molecules. Thus, triphosphorus sulfide and diphosphorus sulfide are viable molecules in the rarefied gas phase. The results of ab initio MO calculations were used to interpret the experimental findings. Tetrahedral (C3v) and triangular (C2v) structures are proposed for the [P,S]+ and [PZS]+0 ions respectively.

Using the technique of neutralization-reionization mass spectrometry(NRMS) we have shown that the elusive thioxophosphane H-P=S and its tautomer H-S-P, (thiohydroxy)phosphinidene, are stable molecules in the gas phase. H-S-P .+ radical cations, generated by electron impact ionization of diethylphosphine sulfide, (C 2 H 5 ) 2 HP=S, are cleanly reduced to H-S-P; whereas H-P=S .- anions, generated in a negative chemical ionization (NCI) experiment with the diethylphosphine sulfide, are readily oxidized to H-P=S

As members of the family of low-coordinated phosphorus compounds, the phosphinidenes (RP) containing subvalent phosphorus (σ1,λ1-P) are of current interest. Until now, no Organophosphiaidene RP (R=Alkyl, Aryl) is known to be stable in the condensed phase. As the results of trapping experiments are questioned, the formation of RP as intermediates is still doubtful [1]. The mass spectrometric decay of some organophosphorus compounds yields radical cations [C6,H5,P]+∗ m/z 108. For these species structures 1 and 2 are conceivable

Phosphinoformic acid is unstable like the N-analogue carbamic acid. We found however that the acid can be stabilized by coordination via P to a (CO)5Cr-moiety [1]. In accordance with the conclusions of Leiserowitz [2] about solid carboxylic acids the crystal formic acid consists of hydrogen of the Cr atom is a distorted bonds between 1.881 and 1.928 A bond of 2.335 A. The angular distortion is small as shown by a maximum deviation of about 2.3° fiom the ideal geometry. At the P atom all bonding angles involving the Cr atom are widened to a maximum of 124° and the other ones are reduced to a minimum of 95°. In the crystal structure two symmetry-related molecules are connected to each other by means of two equivalent hydrogen bonds 06… 07′ and 07… 06′ of 2.660 c length between the carboxylic groups. Because of a twofold disorder along the bond P-C6, proven by bond lengths of 1.269(2) A for C6–06 and 1.264(2) A for C6–07 as well as by the localization and refinement of two H atoms with an occupancy ...