Three new N-phosphinoyl-substituted aminomethanephosphonic acids have been synthesized and characterized: dimethylphosphinoylmethyl-imino-bis(methanephosphonic acid) (1), [3-(dimethylphosphinoyl)-propyl]-imino-bis(methanephosphonic acid) (2), and N-benzyl-Ndimethylphosphinoylmethyl- aminomethanephosphonic acid (3). The latter was isolated as a hydrochloride 3 ・ HCl. The acids have been prepared via Moedritzer-Irani reaction from the corresponding dimethylphosphinoyl-substituted primary and secondary aliphatic amines. Their structures have been confirmed by elemental analysis, IR, 1H, 31P{1H}, 13C{1H} NMR spectroscopy, electrospray ionization mass spectrometry, and single-crystal X-ray diffraction.

A series of thirteen new carbampyl and thiocarbampyl derivatives of N-benzyl-aminomethyl-diinethyl-phosphine oxide have been synthesized and characterized. The compounds were prepared via interaction of N-benzyl-aminomethyl-dimethyl-phosphine oxide with the corresponding isocyanates or isothiocyanates. The composition of the synthesized novel compounds was proved by elemental analysis for nitrogen and the structures were confirmed by IR, H-1-, P-31-P-31{H-1} NMR spectroscopy and by mass spectrometry.

A series of fourteen new 3-[N-substituted carbamoyl (or thiocarbamoyl)]-aminopropyl-dimethyl-phosphine oxides have been synthesized and characterized. The compounds were prepared via reaction of the 3-aminopropyl-dimethyl-phosphine oxide with the corresponding isocyanates or isothiocyanates. The composition of the compounds was proved by elemental analysis and the structures were confirmed by IR, 1 H, 31 P, 31 P{ 1 H} NMR spectroscopy and by mass spectrometry. The structures of 3[(N-phenyl-thiocarbamoyl)amino]propyl-dimethyl-phosphine oxide (5), 3[(N-4- chlorophenyl-thiocarbamoyl)amino]propyl-dimethyl-phosphine oxide (6), and 3[(N-benzyl-thiocarbamoyl) amino]propyl-dimethyl-phosphine oxide (9) have been confirmed by X-ray diffraction.

A group of hitherto unknown 1-aryl-3,3-bis(dimethyl-phosphinoylmethyl)-, 1-benzyl-3,3-bis(dimethyl-phosphinoylmethyl)- and 1-cyclohexyl-3,3-bis(dimethyl-phosphinoylmethyl) ureas and thioureas 1-10 have been synthesized, characterized, and are reported in this article. The compounds were prepared via reaction of corresponding isocyanates or isothiocyanates with the secondary phosporus-containing amine: bis(dimethyl-phosphinoylmethyl)-amine. The composition of the novel compounds was proved by elemental analysis, corresponding structures were confirmed by IR, 1 H-, 31 P-, 31 P{ 1 H}-NMR spectroscopy and by mass spectrometry.

A group of Schiff bases 1 - 18 derived from aminomethyl-dimethyl-phosphine oxide with aromatic aldehydes have been synthesized. Structure and purity of the new compounds were determined by IR, H-1 NMR and P-31(H-1) NMR spectroscopy, mass spectrometry and elemental analysis.

Dissociative electron impact ionization (70 eV) of PhPBr2 yields [C-6,H-5,P](.+) ions with the PhP connectivity, as inferred from its collisional activation mass spectrum. Neutralization-Reionization experiments on this ion indicate that its neutral counterpart, phenylphosphinidene, Ph-P, is a stable species in the dilute gas phase.

EI fragmentation of trimethylphosphine sulfide (CH3)(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 farms 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 [(CH3)(2)((CH2)-C-.)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,),P-SCH3](+.). 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- [(CH3)(2)P = S](+) (m/z 93), dimethyl-methylenephosphonium-[(CH3)(2)P = CH2](+) (m/z 75), and methyl-methylenephosphonium-ion [(CH3)HP = CH2](+) (m/z 61), respectively. The experimental findings are confirmed and complemented by the results of ab initio MO calculations. Copyright (C) 1999 John Whey & Sons, Ltd.

Dimethyl disulfide and dimethyl diselenide are known to readily undergo charge exchange with gaseous conventional radical cations containing oxygen, nitrogen, and sulfur functionalities. In sharp contrast, the radical cations of trimethylphosphine and trimethyl phosphite rapidly abstract CH3S. and CH3Se. groups from dimethyl disulfide and dimethyl diselenide, respectively, in a dual-cell Fourier-transform ion cyclotron resonance mass spectrometer, These sorts of abstraction reactions have been reported earlier only for distonic radical cations (ions with spatially separated charge and radical sites). Isomerization of the organophosphorus radical cations to their distonic forms prior to or during the reaction was ruled out by demonstrating that the connectivity in (CH3)(3)P-.+ does not change during the reaction: the CH3S. abstraction product has the structure (CH3P+-SCH3. Instead, the abstraction reactions are likely initiated by thermoneutral charge exchange. The neutral phosphorus compound then replaces a CH3S. or CH3Se. group in ionized dimethyl disulfide and ionized dimethyl diselenide, respectively, In support of this mechanism, three different neutral phosphorus compounds were shown to replace CH3S. in the radical cation of dimethyl disulfide. Phosphorus radical cations with high recombination energies were found to react with dimethyl disulfide by exclusive charge exchange, Hence, the abstraction reactions require a radical cation with a recombination energy close to the ionization energy of dimethyl disulfide (8.1 eV) and dimethyl diselenide (7.9 eV). Further, the reactions seem to be limited to phosphorus-containing ions since radical cations with nitrogen and sulfur functionalities do not undergo these reactions even when their recombination energies are close to 8.1 eV.

Abstract 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:

The structure of the gaseous long-lived radical cation generated upon electron ionization of trimethylphosphine oxide, (CH3)3PO, has been investigated by using ion-molecule reactions in a Fourier transform ion cyclotron resonance mass spectrometer. A radical cation with the connectivity of trimethylphosphine oxide is expected to react by facile electron transfer with triethylamine, pyridine and dimethyl disulfide since all these reactions are highly exothermic. However, no electron transfer reactions were observed. Instead, the radical cation transfers a proton to triethylamine and to pyridine, i.e., acts as a Brønsted acid. Further, the radical cation abstracts CH3S from dimethyl disulfide and hence demonstrates behavior characteristic of a distonic ion with a carbon radical center. This reactivity is unprecedented for a radical cation such as (CH3)3P+-O with the odd spin located at an oxygen atom. These experimental results indicate that the initially generated radical cation (CH3)3P+-O undergoes unimolecular isomerization to (CH3)2P+(OH)CH2 within a millisecond time frame. Ab initio molecular orbital calculations carried out at the unrestricted second-order Møller-Plesset (UMP2/6-31G** + ZPVE) level of theory support this conclusion by predicting that (CH3)2P+(OH)CH2 lies 23 kcal mol−1 lower in energy than (CH3)3P+-O. The energy barrier for unimolecular [1,3]-hydrogen atom migration in (CH3)3P+-O is estimated to be 24 kcal mol−1. This study demonstrates that the PO moiety provides a very strong driving force for hydrogen shifts in phosphorus containing radical cations.

The reactivity of the prototypical phosphorus-containing ylidion (alpha-distonic ion) (CH2PH3+)-C-. has been investigated in the gas phase by using a dual cell Fourier-transform ion cyclotron resonance mass spectrometer. The ion (CH2PH3+)-C-. and its more stable conventional isomer CH3PH2.+ show distinctly different reactivities toward neutral reagents. This observation contrasts the facile interconversion of the analogous sulfur- and oxygen-containing distonic ions (CH2SH2+)-C-. and (CH2OH2+)-C-. with their conventional isomers CH3OH.+ and CH3SH.+, respectively, within collision complexes in the gas phase. Bracketing experiments yield a proton affinity of 190.4 +/- 3 kcal mol(-1) for the phosphorus atom in (CH2PH2)-C-.. Together with a calculated heat of formation for (CH2PH2)-C-., this value yields a heat of formation of 217 +/- 3 kcal mol(-1) (at 298 K) for the distonic ion (CH2PH3+)-C-..

Using the technique of neutralization-reionization mass spectrometry (NRMS) it could be shown that the elusive phosphorotrithious acid (HS)(3)P is a stable molecule in the rarefied gas phase. A triple propene elimination from the molecular ions of the dipropyl ester of propylphosphonotrithioic acid, PrP(S)(SPr)(2), (70 eV EI) yields m/z 130 radical cations of composition ''[H3PS3](.+)''. Analysis of their collisional activation (CA) mass spectrum using thermochemical data shows that these ''[H3PS3](.+)'' ions have the structure [(HS)(3)P](.+) rather than that of the tautomer [(HS)(2)P(=S)H](.+). Subjected to a NRMS experiment, these ions retain their structure and are cleanly reduced to (HS)(3)P. The results are entirely compatible with ab initio MO-calculations executed at the HF/3-21G* and HF/6-31G** levels of theory (GAUSSIAN 92 system of programs). The calculations predict that [(HS)(3)P](.+) and [(HS)(2)P(=S)H](.+) and their respective neutral counterparts are local minima which are separated by high potential energy barriers. Neutral (HS)(3)P is calculated to be lower in energy than its tautomer (HS)(2)P(=S)H but upon ionization this order of stability is reversed.

Starting from Mo(CO)6 and disulfanes R2P(S)-S-S-P(S)R2 the “trimetallic” tetranuclear clusters Mo2WCuS4I(R2PS2)4 3 (R = Et (a), Pr (b)) were obtained via the dinuclear compounds Mo2S4(R2PS2)2 1 and the trinuclear complexes Mo2WS4(R2PS2)4 2. The crystal structure of 3b shows a cubane-type core Mo2WCuS4. Both Mo atoms and the W atom are chelated by a dithiophosphinato ligand. One Mo and the W atom are bridged by the fourth ligand. The coordination of W and Mo2 is octahedral, of Mo1 trigonal bipyramidal, and of Cu tetrahedral.

Reaction of Mo3S4(R2PS2)4 1 (a: R = Et, b: R = Pr) with HgI2 in THF yields the diamagnetic title complexes [Mo3S4(R2PS2)4HgI2]3. The crystal structure of [3a (H2O)] . 2CH2Cl2 shows the complexes to consist of a triangular array of Mo atoms which are bridged by mu2-S atoms and capped by a mu3-S atom. Each of the Mo atoms is chelated by a dithiophosphinato ligand Et2PS2- and in addition two Mo atoms are bridged by a Et2PS2- ligand while the H2O molecule is bonded weakly to the third Mo atom. Thus, all Mo atoms reveal a distorted octahedral coordination sphere. HgI2 is ''peripherally'' bonded to the cluster via two S atoms, one of which belongs to a chelating ligand and the other one to the bridging ligand. Space group P1BAR, lattice constants a = 12.157(2), b = 15.284(3), c = 16.049(3) angstrom, alpha = 115.56(1), beta = 107.35(1), and gamma = 94.62(1)degrees; Z = 2, d(calc) = 2.23 mg/mm3; 4236 observed reflections, R = 0.068. In organic solvents complexes 3 are strong electrolytes. VT-P-31 NMR data suggest a stepwise dissociation of 3 with formation of [Mo3S4(R2PS2)3]+[(R2PS2)HgI2]- and elimination of the bridging ligand from the cluster.

Reactions of clusters Mo3S4L4 (2) (L=R2P(S)S−; R=Et (a), Pr (b)) with MI2 (M=Zn, Cd, Hg) in the presence of pyridine yieided ionic clusters [Mo3S4L3py3]+[MI3py]− (M=Zn (9), Cd (10); R=Et (a), Pr (b)) and [Mo3S4L3py3]+[HgI3]− (11) (L=Pr2P(S)S−), respectively. The cluster cations consist of a triangular array of Mo atoms which are bridged by three S atoms and capped by the fourth S atom. Each of the Mo atoms is chelated by one L and coordinated by one pyridine. 9a crystallizes in the monoclinic space group P21 with Z=2 formula units in the unit cell of dimensions a=1120.9(2), b=1756.3(3), c=1447.3(2) pm, β=105.31(1)°, Dc=1.98 mg/ mm3. The crystal structure was refined to R = 0.04 using 5599 observed reflections and consists of [Mo3S4(Et2PS)3py3]+[ZnI3py]−. The coordination number of the Mo atoms is 8. The average distance MoMo is 276.6(2) pm. The Zn atom is coordinated tetrahedrally with average distance ZnI of 259.0(2) and ZnN of 208.8(11) pm.

The syntheses of tetranuclear complexes Mo2W2S4L6 3 and Mo2Co2S4L2(CO)2(CH3CN)2 4 (L = R2PS2-; a: R = Et, b: R = Pr) containing the cubane-type Mo2M2S4 core are reported. While in 4 both Mo atoms are chelated by L, the dithiophosphinato group acts as a chelating and bridging ligand in 3. It is shown that there exist four isomers of 3 which differ not only in the function of L but also in the kind of metals which are chelated and bridged. Magnetic and NMR spectroscopic data are given. The structure of a mixed crystal of the two beta-isomers of 3a containing three bridging and three chelating ligands L is reported: orthorhombic space group Pbca Z = 8 and lattice parameters a = 2186.6(7), b = 2264.0(7), and c = 2386.7(6) pm.

The diamagnetic tetranuclear cluster complexes Mo3CuS4I(R2PS2)4.C5H5N 2 (a: R = Et, b: R = Pr) are obtained by reaction of Mo3S4L4 (L = R2PS2-) 1 with Cul and pyridine. Each Mo atom of the cubane-type Mo3CuS4 core is chelated by L. Two of the Mo atoms are bridged by the fourth L, while a pyridine ligand completes the coordination sphere of the third Mo atom, and iodine is bonded to the Cu atom. Magnetic, NMR- and MS-spectroscopic data are given. 2b crystallizes in the monoclinic space group P2(1)/n with Z = 4 and lattice parameters a = 21,164(7), b = 10,653(3), c = 25,455(8)angstrom, and beta = 106,25(3)-degrees.

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 diamagnetic tetranuclear cluster complexes Mo3CuS4I(R2PS2)4•C5H5N 2 (a: R=Et, b: R=Pr) are obtained by reaction of Mo3S4L4 (L = R2PS2-) 1 with CuI and pyridine. Each Mo atom of the cubane-type Mo3CuS4 core is chelated by L. Two of the Mo atoms are bridged by the fourth L, while a pyridine ligand completes the coordination sphere of the third Mo atom, and iodine is bonded to the Cu atom. Magnetic, NMR- and MS-spectroscopic data are given. 2b crystallizes in the monoclinic space group P21/n with Z = 4 and lattice parameters a = 21,164(7), b = 10,653(3), c = 25,455(8)Å, and β = 106,25(3)°.