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The [pi]-bonding chemistry between phosphinidene and phosphonium ion was studied by computational methods. It was shown that the protonated species behave more like the heavy carbene for their weak [pi]-bonding character.

The synthesis, structures and the pseudorotation of the derivatives of Cyclotetraphosphinophosphonium ions are described. The frameworks of the cations in the solid state are found to be the snapshots of different conformational isomers within the solution-phase pseudorotation process.

A study was conducted to examine the necessity of the covalent connection between the phosphodianion and triose sugar portions of the substrate by carving up glyceraldehyde 3-phosphate (GAP) into the minimal neutral two-carbon sugar glycolaldehyde and phosphite dianion pieces. Based on the result it was proposed that the interactions of the closed flexible loops of TIM and OMPDC with the substrate phosphodianion group represent a common strategy that enables efficient recruitment of the intrinsic binding energy of a small remote binding determinant for transition state stabilization.

The first sequential one-pot double dearomatization of bis(N-benzyl-P,P-diphenylphosphinamides) is described via an anionic cyclization. The analysis provides a facile route of accessing the multifunctional systems with the antitumor properties, as the doubly phosphorylated systems prove to be active against a series of cancer line cells.

The binding of the most common metal cations of cytoplasm ([Li.sup.+], [Na.sup.+], [K.sup.+], [Mg.sup.2+] and [Ca.sup.2+] to a model molecule having an intramolecular hydrogen-bonding network, myo-inositol-2-monophosphate was studied. The results revealed a strong coupling between the conformational preference of these components and the interactions with metal ions, the environmental pH, and the dielectric strenght of the surrounding medium.

Ab initio calculations are performed to determine the structures and binding energies of open and cyclic complexes formed from the [sp.sup.2] [[H.sub.2]C=PH and HP=PH (cis and trans)] and [sp.sup.3] [P[H.sub.2](C[H.sub.3]) and P[H.sub.3]) hybridized phosphorus bases and their corresponding protonated ions. The experimental measurements of [super 2h][J.sub.p-p] are able to differentiate between open and cyclic complexes.

The structure, spectra, and rearrangement mechanisms of P[H.sub.2][F.sub.3], the first member of the P[H.sub.n][F.sub.5-n] series and a prototype for molecules that undergo rotational isomerism, are analyzed. The results have identified the spectral fingerprints that could distinguish various rotational isomers that could form a powerful basis for the characterization of various rotational isomers of P[H.sub.2][F.sub.3] when used along with high resolution measurements.

The transmission electron microscopy and atomic force microscopy was used to study the nature of strain relaxation in GaP films grown on (100), (311)A, and (311)B GaAs by molecular beam epitaxy. Energy consideration in thin films containing a dislocation indicates that the minimum energy position for the misfit dislocation is located in the softer substrate near the interface.

A study was conducted to investigate the formation of compositional modulation and atomic ordering in InGaP films. The results indicate that the surface diffusion is the main driving mechanism for compositional modulation on InGaP films grown by CBE and surface reconstruction shows a strong effect on both compositional modulation and the Cu[Pt.sub.[beta]] atomic ordering phenomena.

The high-level ab initio electronic structure theory is used to calculate the heats of formation of diphosphene (cis- and trans-[P.sub.2][H.sub.3]), phopshinophosphinidene (singlet and triplet [H.sub.2]PP) and diphosphine ([P.sub.2][H.sub.4]), and those of the [P.sub.2]H and [P.sub.2][H.sub.3] radicals ensuing from PH bond cleavages. The calculated results for the hydrogenation reactions have shown that substitution of an organic substituent for H improves the energetics, suggesting that secondary diphosphines and diphosphenes are potential candidates for use in a chemical hydrogen storage system.

Synthetic, X-ray structural and reactivity studies of Cp*[Ru.sup.IV] complexes containing bidentate dithiocarbonate, xanthate, carbonate, and phosphinate ligands (Cp*=[eta.sup.5]-[C.sub.5][Me.sub.5] was carried out. The observed reversible one step four-electron redox reactions in the [Ru.sup.II] complex [[Ru(DTC)(CO)(PP[h.sub.3])([mu]-SPh)].sub.2] indicates that electron-rich Ru(DTC) complexes are potential candidates as multielectron catalysis.

One-step redox reaction of the appropriate N-alkyl, N-cycloalkyl and N-aryl substituted [alpha]-diimines which afforded N-heterocyclic phosphenium ions was investigated. A redox reaction of this type was found to be involved in the reaction of an N-heterocyclic germylene with P[Cl.sub.3] and As[Cl.sub.3] to form the [[Ge[Cl.sub.5]].sup.-] salts of the corresponding phosphenium and arsenium cations.

A novel method is described for the synthesis of phosphocitrate (PC) starting from triethyl ester of citric acid and MeOP[Cl.sub.2]. This novel method is based on selective stepwise hydrolysis of ester moieties from the intermediate Me-O-P(O)(Cl)(Z) (Z = triethylcitrate), which has allowed to prepare partially esterified derivatives of PC with good yield and purity without using chromatographic purifications.

The representative of P,P,P-trichloroylides-5-methyl-2-phenyl-4-(trichlorophosphoranylidene)2,4-dihydro-3H-pyrazol-3-one was synthesized and characterized. Some chemical properties were studied and compared with one of P,P,P-trichloroylides-5-methyl-2-phenyl-4-(trichlorophosphoranylidene)2,4-dihydro-3H-pyrazol-3-one.

The nature of valency and bonding in the highly unusual [O.sub.2]P[R.sub.3] 'phosphadioxirane' species isolated as an intermediate in the reaction of [super 1][O.sub.2] with organic phosphines P[R.sub.3] is investigated. The ramifications and limits of the cyclic hyperbonding phenomenon in analogous carbon compounds are examined and some broader implications of its structural representation and nomenclature are discussed.

Two-dimensional [sup.1]H-[sup.31]P Fast-HMQC was tested for determination of the presence in low concentrations of organophosphorus compounds related to the Chemical Weapons Convention. This method, based on inverse detection, demonstrated high sensitivity and selectivity. Background signals, such as solvent peaks, are suppressed with good efficiency, and organophosphorus compounds present at a concentration level 1-10 [micro]g/mL can be detected within a few hours. In addition, phosphorus-selective one-dimensional [sup.1]H-[sup.31]P HSQC-TOCSY was applied to produce a complete proton spectrum of selected organophosphorus compound from a sample containing intense background resonances. Application of the methods presented in this paper resulted in considerably improved performance of NMR spectroscopy as a complementary technique for screening as well as identification of chemical warfare agents in environmental samples.

Two novel manganese(III) complexes PPh(sub 4)[Mn(mal)(sub 2)(H(sub 2)O)(sub 2)] (1) and AsPh(sub 4)[Mn(mal)(sub 2)(H(sub 2)O)(sub 2)] (2) were prepared and the structure was determined. It consists of hydrogen-bonded anionic [Mn(mal)(sub 2)(H(sub 2)O)(sub 2)](super -) and cationic tetraphenylarsonium layers while both the compounds show weak ferromagnetic interactions.

The synthesis and characterization of two new anhydrous pip polymers containing the tin(II) and copper(II) ions namely [Sn(pcp)]and [Cu(pcp)] is presented. It is observed that there is a significant interaction with a C-C bond of one phenyl ring caused by the lone pair of tin(II) and the [Cu(pcp)] complex displays the polymeric columnar structure formed by two intersecting sinusoidal ribbons of Cu(II) ions bridged by the bifunctional phosphinate ligands.

The mechanistic issues associated with the production of terminal phosphide complexes of molybdenum by reaction of white phosphorus (P4) with reactive trivalent molybdenum trisamides are studied. Post-rate determining steps of the P4 activation process were examined in a search for minima on the reaction's potential energy surface, leading to the proposal of two plausible, parallel, bimetallic reaction channels.

Cationic cluster Ti2P6(super +) is studied within density functional theory. The structure of this cluster is predicted to be a slightly distorted tetragonal prism and the dissociation energy of this cationic cluster is higher than that of the known compound, [(P5)2Ti](super 2-), because of the different bonding in these two compounds.

A structural and optical characterization of scepterlike micrometer-sized free-standing structures, composed of a long InGaP rod with a metallic sphere on its top, grown on polycrystalline InP substrates is presented. The InGaP rods present essentially constant Ga composition within a fluctuation of approximately 10% and efficient optical emission.

The equilibrium geometries, energies, harmonic vibrational frequencies, and nucleus independent chemical shifts (NICSs) of the ground state of P(sub 5)- anion, [Ti (mu(super 5)-P5)]- and sandwich complex [Ti(mu(super 5)-P5)(sub 2)](super 2-) are calculated. The results revealed that in each of the three molecules, the P-P and Ti-P bond distances are perfectly equal.

The syntheses and structures of five new zinc phosphites such as [Zn(HPO3)(C4H6N2)], [Zn2(HPO3)2(C10H10N2)2]2, [Zn(HPO3)(C14H14N4)0.5], [Zn2(HPO32(C14H14N4)].0.4H2O and [Zn2(HPO3)2(C14H14N4)] is reported. Primary (zinc and phosphorus tetrahedral), secondary building units (4-ring), and tertiary units (triple4-rings) are involved to construct the inorganic or organic hybrid materials.

A detailed potential-energy surface of C4P is established. This involves 12 minimum isomers and 27 interconversion transition states at the Becke exchange functional and nonlocal LYP correlation functional (B3LYP), quadratic configuration interaction method with single and double substitutions (QCISD), and couple cluster method with single, double and noniterative triple substitutions (CCSD(T)) (single-point) levels.

Design and synthesis of chelating bisphosphines functionalized with the smallest chemical unit 'H' on the P(super III) centers (PH2CH2)2CHCH2NHPh and (PH2CH2)2CHCONHPh are described. Transition-metal/organometallic compounds derived from chelating primary bisphosphines will play vital roles in catalytic processes.

A study is carried out on the effect of recrystallization on the crystalline structure and properties of P(VDF-TrFE)65/35 mol % samples that had previously been irradiated with high-energy electrons at doss of 60, 85, and 100 Mrad. The findings suggest that recrystallized polymers can be used in applications requiring high-performance electroactive polymers.

Semi-insulating InP is implanted with MeV P, As, Ga and In ions, and the resulting evolution of structural properties with increased annealing temperature is analyzed using double crystal x-ray diffractometry and cross sectional transmission electron microscopy. The studies show that the amount and type of damage caused by implantation does not scale with implant ion atomic mass.

Several ab initio studies are conducted to explain the different atomic, as well as the electronic structures of black phosphorus (BP). The presence of the Van der Waals interaction is shown to lead to a significant enhancement of the materials band structure.

Amino acid ionic liquid trihexyl(tetradecyl)phosphonium methioninate [[P.sub.66614][Met] and prolinate [[P.sub.66614][Pro] has absorbed C[O.sub.2] in nearly 1:1 stoichiometry. Density functional theory calculations have supported the 1:1 reaction stoichiometry and have predicted reaction enthalpies with calorimetric measurements isotherms.

A proline derivative-catalyzed cross aldol reaction with ketones was carried out in presence of racemic [alpha]-acylphosphinates and formylphosphinate hydrate as substrates. The reaction gave a mixture of two diastereomers of the corresponding [alpha]-hydroxyphosphinates with high enantioselectivities of 99% ee due the presence of preexisting phosphorus stereogenic center.

The synthesis, structures, optical and redox properties, and reactivity of phosphaporphyrins prepared via acid-promoted dehydrative condensation is presented. The incorporation of a phosphorus atom into the core is found to be a highly promising way to modify the fundamental properties of the porphyrin 18[pi] system which could also be used as reliable tool to stabilize uncommon 22[pi] and 20[pi] systems through the chemical modifications at the core phosphorus atom.

Highly stereoselective synthesis of [alpha]-D-mannopyranosyl phosphosugars from 4,6-O-benzylidene-protected mannosyl thioglycosides bearing ester functionality in the 3-O-position is described. The synthesis involved the coupling with ammonium salts of phosphosugars on activation with 1-benzenesulfinyl piperidine, 2,4,6-tri-tert-butylpyrimidine, and trifluoromethanesulfonic anhydride.

A photochemical reaction of mixed phosphonium-iodonium ylides with acetylenes to obtain [[lambda].sup.5]-phosphinolines, a rare class of phosphorus heterocycles rarely accessible by other methods is reported. The data obtained from X-ray diffraction and nuclear magnetic resonance ( NMR) spectra indicated the superposition of ylidic and aromatic structures for phosphinolines.

The synthesis of a series of C,C-diacetylenic phosphaalkenes from 1-chloropenta-1,2-dien-4-ynes in a reaction with Mes*P[Cl.sub.2] (Mes* = 2,4,6-[([super t]Bu).sub.3]Ph) in the presence of LDA and isomeric butadiyne-substituted phosphaalkenes obtained from 3-chloropenta-1,4-diynes is described. Both the isomers obtained represent rare examples of diethynylethenes in which a constituting methylene is replaced by a phosphorus center.

The ion-molecule reactions of [HOO.sup.-] with O,S-dimethyl methylphosphonothioate in a modified linear ion-trap mass spectrometer was explored to study the alkaline perhydrolysis of the nerve agent O-ethyl S-[2-(diisopropylamino)ethyl] methylphosphonothioate (VX). The intramolecular sulfur oxidation process explained the selective perhydrolysis of the nerve agent to relatively nontoxic products based on the elimination of a sulfur moieyt which deactivates the nerve agent VX.

A method is described for reversing the polarity of a hydrogen atom of water by using a hexacoordinated phosphorus species. The method has enabled a reductive deuteration of carbonyl compounds by using [D.sub.2]O and the umpolung of hydrogen atom is achieved by using tautomerization of phosphorus compounds.

Mixed micelles of cetyltrimethylammonium bromide (CTABr) or dodecyltrimethylammonium bromide (DTABr) and the [alpha]-nucleophile, lauryl hydroxamic acid (LHA) have accelerated the dephosphorylation of bis(2,4-dinitrophenyl)phosphate (BDNPP). The results are consistent with a mechanism involving concurrent nucleophilic attack by hydroxamate ion on the aromatic carbon and at phosphorus.

The homolytic bond dissociation enthalpies (BDEs) of the acidic C-H bonds in a series of phosphonates and related phosphorus-containing compounds are determined by a combination of their equilibrium acidities and the oxidation potentials of their conjugate anions, which are measured in DMSO solution. The acidifying effect of an [alpha]-C[O.sub.2]Et group is stronger than that of an [alpha]-P(O)[(OEt).sub.2] group in the same substrates, indicating that the larger acidifying effect of the [alpha]-C[O.sub.2]Et group is associated with the resonance delocalization rather than with the field/inductive and polarizability effects.

Protonation of a bidentate xantphos-phosphole ligand by [HBF.sub.4] to obtain only one enantiomer of a cyclic phospholium dihydropholene structure is reported. The results from DFT calculations demonstrated that protonation initially took place at the phosphorus atom of the phosphole moiety to obtain a transient P-H phospholium salt, which in turn protonated the C=C double bond of the second phosphole unit.