Molecular fragmentations: Part VIII. Structures and energies of mass spectral fragments derived from tetraphosphorus trisulphide

Molecular structures and energies have been calculated in the MNDO approximation, for P₄S₃ and its molecular ion P₄S₃⁺, and for the mass spectral fragment pairs: (P₃S₃⁺ + P), (P₃S₂⁺ + PS), (P₃S⁺ + PS₂), (P₂S₃⁺ + P₂), (P₂S₂⁺ + P₂S), (P₂S⁺ + P₂S₂), (P₂S₂), PS₃⁺ + P₃), (PS₂⁺ + P₃S), (PS⁺ + P₃S₂), and (PS⁺ + P₂S + PS). Three distinct energy minima were found for each of P₂S₂⁺ and P₂S₂, and two minima for each of P₂S⁺, P₂S, PS₃⁺, PS₃⁺, PS₂⁺, PS₂, P₃⁺ and P₃. The fragments arising from P₄ and P₄⁺ were also investigated. The structures are discussed in terms of the Jahn—Teller effect, whose predictions are fulfilled without exception.     

Semi-empirical Scf-Mo study of the mass spectral fragmentation of tetramethyldiphosphine

Structures and enthalpies of formation have been calculated, in the MNDO approximation using UHF wave-functions for open shell species, for tetramethyldiphosphine, Me₄P₂, and the major ions in its mass spectrum: Me₄P₂⁺, Me₃P₂H⁺, Me₃P₂⁺, Me₂P₂H₂⁺ (3 forms), Me₂P₂H⁺ (3 forms), Me₂P₂⁺ (3 forms), MePPCH₂⁺ (3 forms), MeP₂⁺ and MePCH₂⁺, together with all the corresponding neutral fragments. Appearance potentials are calculated for all the ions, and possible fragmentation pathways deduced.     

On the reaction of Kr+ with hydrogen

The reaction of Kr⁺(²P_3/2) and Kr⁺(²P_1/2) with H₂ are examined using a conventional ICR and a tandem Dempster- ICR instrument. The accidentally near-resonant charge-transfer reaction of CO⁺ with Kr was used to prepare a nearly pure ²P_3/2 state Kr⁺ beam to evaluate rates of reaction of the ²P_3/2 and ²P_1/2 state with H₂. It was found that the Kr⁺(²P_3/2) reacts faster than the Kr(²P_1/2) and a negligible activation energy exists for both reactions.     

Fine structure of As−

The energies of the As^? fine structure components 4p^{4 3} P ₁ and 4p^{4 3} P ₀ have been determined relative to the 4p^{4 3}P₂ ground state by using photodetachment electron spectroscopy. Fine structure splittings of ΔE(³ P ₁ ? ³ P ₂) = 125(3) meV and ΔE(³ P ₀ ? ³ P ₂) = 166(5) meV have been obtained. It is the first experimental determination of the energy of the J = 1 level and an improvement of the accuracy for the J = 0 level. Previous isoelectronic extrapolations are consistent with the experimental values.     

Spectroscopy and kinetics of the 1P1 and 3P2 states of Hg 6s6p in xenon

The spectra and kinetics observed following excitation of Hg 6s6p(¹P₁) in xenon show the occurence of complex attachment and relaxation processes. The ¹P₁ attaches to Xe in termolecular collisions to produce HgXe E¹1, which emits a broad band with λ_max ≈ 2150 Å. Addition of krypton to Hg, Xe mixtures enhances the E-state emission by atom exchange with an HgKr^* complex. The E state also undergoes collisional deactivation by Xe, rate coefficient (1.75 ± 0.25) × 10⁻¹¹ cm³ molecule⁻¹ s⁻¹, to generate ³P₂. However, the predominant route for ³P₂ formation is via collision of ¹P₁ with Xe, rate coefficient ≈ 4 × 10⁻¹² cm³ molecule⁻¹ s⁻¹. With [Xe] at 760 Torr, about 75% of the generated ³P₂ is attached in the form of the HgXe(C ³2) complex; lifetimes up to 600 μs have been observed. Two new emission bands occur when ³P₂ is prepared in xenon. A sharp feature, slightly blue-shifted from the forbidden ³P₂:¹S₀ line, results when ³P₂ and Xe approach on the D ³1 surface. The other band is broad with λ_max ≈ 2520 Å; the carrier is assigned to an HgXe₂(³2_u) complex. Rate coefficients for deactivation of ³P₂ to lower ³P_J states have been measured.     

On the energy difference between the lP and 3P states of the beryllium isoelectronic sequence

Wave functions of the ¹S (ground state), ³P and ¹P states for the beryllium isoelectronic sequence have been obtained in various approximations. The HF ²p orbitals for the ¹P and ³P states are similar except for Be, where the ²p orbital is quite diffuse for the ¹P state. The difference between the experimental E(¹P) – E(³P) and the HF E(¹P) – E(³P) is 0.62 eV for Be and 1.17 ～ 1.40 eV for B⁺ ～ F⁵⁺. The disagreements are attributed to the correlation effects between the 2s and 2p electrons. This is confirmed by ci calculations. It is shown that a limited basis SCF calculation reproduces the above feature of the HF results if we treat the orbital exponents as the variational parameters. The use of the Slater values for the orbital exponents is shown to be inadequate especially for the Be ¹P state. The conclusions of this paper will be useful for discussing the V–T separations of H₂ and C₂H₄.     

Developments in the theory of cationic polymerisation. Part IX some effects of the complex formation between cations and monomers

The formation of complexes P⁺_nM between a propagating carbenium ion P⁺_n and the monomer, M, is considered from several points of view - (i) Under the most usual conditions the formation of the P⁺_nM reduces the population of ion-pairs, P⁺_nA⁻, drastically. This can account for the frequently found nil-effect of common ion salts on the rate of attack of carbenium ions on alkenes in initiation, model reactions, and polymerisations. - (ii) The formation of P⁺_nM increases the degree of dissociation α of P⁺_nA⁻, so that all the estimates of α on which kinetic schemes have been based, are too low. - (iii) The very high polymerisation rates found for n-donor monomers, say 4-MeO-styrene or N-vinylcarbazole compared to styrene, may be attributable not, primarily, to a difference in rate-constants, but to a difference in ionic population. This is because the fast P⁺_nM is in greater excess over the slow P⁺_nA⁻ for more strongly complexing n-donors than for the π-donors. - (iv) Since the nature of the P⁺_nM is different for every monomer, a comparison of their propagation rate-constants k⁺_pM is hardly meaningful and valid comparisons can only be made between the k⁺_p of the P⁺_n. The measurement of these requires extreme conditions, either extrapolations to [P⁺_n] = 0 and [M] = 0, or the use of highly polar solvents in which neither M nor the anion can compete with the solvent for the solvation of the P⁺_n.     

Multireference configuration interaction study on spectroscopic parameters and molecular constants of PO and PO+

The highly accurate valence internally contracted multireference configuration interaction (MRCI) approach has been employed to investigate the potential energy curves (PECs) for the X²Π, b⁴Σ^?, C²Σ^? states of PO and the X¹Σ⁺ state of PO⁺. For these electronic states, the spectroscopic parameters of the isotopes (P¹⁶O, P¹⁸O, P¹⁶O⁺, and P¹⁸O⁺) have been determined and compared with those of the investigations reported in the literature. The comparison shows that excellent agreement exists between the present results and the available experiments. With the PECs determined here, the first 30 vibrational states for P¹⁶O(X²Π, b⁴Σ^?), P¹⁸O(X²Π, b⁴Σ^?), P¹⁶O⁺(X¹Σ⁺), and P¹⁸O⁺(X¹Σ⁺) are computed when the rotational quantum number J equals zero (J = 0). The vibrational level G(υ), inertial rotation constant B_υ and centrifugal distortion constant D_υ are determined when J = 0. All the results of vibrational states except for P¹⁶O (X²Π) are reported for the first time. © 2011 Wiley Periodicals, Inc. Int J Quantum Chem, 2011     

Phosphorus Oligomerization in Zintl Phases: Synthesis,Crystal Structure,and Bonding Analysis of Mixed Alkali and Alkaline‐Earth Metal Phosphides

Pnictides α‐Ba₅P₄ and KBa₄P₅ were prepared by melting the elements. The α‐Ba₅P₄ compound crystallizes in the orthorhombic system (Sm₅Ge₄‐type), space group Pnma, Z = 4, a = 8.330(3), b = 16.503(3), c = 8.405(2)Å, it contains two anionic species : P₂^4— dumbbells and P^3—. The KBa₄P₅ compound crystallizes in the tetragonal system, space group P4₃2₁2, Z = 4, a = 8.559(1), c = 16.102(2)Å, it contains trimers P₃^5— and dumbbells P₂^4—. The crystal structures were solved from single crystal X‐ray data and refined by full‐matrix least‐squares to agreement factors R1 = 0.047 and 0.038, respectively. Using ionic charges, α‐Ba₅P₄ is formulated as [5Ba²⁺, 2P^3—, P₂^4—] and KBa₄P₅ as [K⁺, 4Ba²⁺, P₂^4—, P₃^5—]. The level of oligomerisation in these structures depends upon the overall valence electron content, bonding within the anionic oligomers has been analyzed on the basis of EHMO calculations and compared to classical or hypervalent bonding in other phosphide compounds.     

Self-consistent calculation of excited 3P state wave functions of atoms

A variation perturbation method in the Hartree–Fock scheme has been described to calculate excited ³P state wave functions of atoms. The starting wave functions are obtained from a study of the singularities in the dynamic polarizability calculation [1]. The 2³P, 3³P and 4³P states of He, Li⁺, Be²⁺, B³⁺ and C⁴⁺ are studied. The results obtained are in satisfactory agreement with experimental values and with other accurate theoretical estimates.     

Volumes of mixing and theP * effect: Part II. Mixtures of alkanes with liquids of different internal pressures

The Flory theory of solution thermodynamics is used to predict exess volumes for systems containing a series of n-alkanes mixed with liquids of higher P^* parameter and internal pressure, i.e., cyclopentane, cyclohexane, carbon tetrachloride, benzene and dioxane as well as of lower P^*, i.e., decamethyltetrasiloxane. Trends of V ^E , e.g. changes of sign with alkane carbon number are well predicted and indicate the importance of the P^* contribution in V ^E . Mixtures of hexane isomers with liquids of much higher P^* typically have large excess enthalpies through zero as an S-shaped curve against composition which is negative on the side of the high P^* component. This behaviour is interpreted as arising from increasingly large negative P^* contributions in V ^E .     

Reevaluation of electronic polarization energies in organic molecular crystals

Effective electronic polarization energies for positive P⁺_eff and negative P⁻_eff charge carriers in polyacene crystals have been reevaluated. By comparing the P⁺_eff and P⁻_eff values obtained from the analyses of reported energy parameters with calculated data, it is shown that the widely accepted assumption that P⁺_eff = P⁻_eff in polyacene crystals is not valid. By applying recently reported data on optical E^opt_G and adiabatic E^ad_G energy gap values, the contribution of molecular (vibronic) polarization in the total effective polarization energies W⁺_eff and W⁻_eff has been estimated, and modified energy diagrams for polyacene crystals have been presented. Further, due to practically constant values of observed and calculated P⁺_eff and P⁻_eff in polyacenes, the gap energies between positive and negative charge carrier conduction levels have been estimated for several related aromatic hydrocarbons.     

The production of Te atoms by the multiphoton dissociation of diethyltelluride

Detection of Te atoms in the ground ³P^2,1,0 states has been accomplished using two-photon laser-induced fluorescence (LIF) and “2 + 1” multiphoton ionization (MPI). Te atoms were produced by multiphoton dissociation of (C₂H₅)₂Te in the region 358–395 nm. The LIF and MPI experiments utilize selective excitation of the 6p ³P_J′←5p ³P_J″ and 7p ³P_J′←5p ³P₂ transitions by two-photon absorption. Line strength intensities for the individual J′ ← J″ fine structure pairs of the 6p ³P_J′ ← 5p ³P_J″ two-photon transitions were calculated and compared to the LIF data. Intensities of these transitions of Te atoms are compared to analogous ³P ← ³P transitions in S and O atoms.     

Synthesis,Structure, Spectroscopic,and Electrochemical Properties of Highly Fluorescent Phosphorus(V)–meso‐Triarylcorroles

The synthesis, spectroscopic, and electrochemical properties of seven new P^V–meso‐triarylcorroles ( 1 – 7 ) are reported. Compounds 1 – 7 were prepared by heating the corresponding free‐base corroles with POCl₃ at reflux in pyridine. Hexacoordinate P^V complexes of meso‐triarylcorroles were isolated that contained two axial hydroxy groups, unlike the P^V complex of 8,12‐diethyl‐2,3,7,13,17,18‐hexamethylcorrole, which was pentacoordinate, or the P^V complex of meso‐tetraphenylporphyrin, which was hexacoordinate with two axial chloro groups. ¹H and ³¹P NMR spectroscopy in CDCl₃ indicated that the hexacoordinated P^V–meso‐triarylcorroles were prone to axial‐ligand dissociation to form pentacoordinated P^V–meso‐triarylcorroles. However, in the presence of strongly coordinating solvents, such as CH₃OH, THF, and DMSO, the P^V–meso‐triarylcorroles preferred to exist in a hexacoordinated geometry in which the corresponding solvent molecules acted as axial ligands. X‐ray diffraction of two complexes confirmed the hexacoordination environment for P^V–meso‐triarylcorroles. Their absorption spectra in two coordinating solvents revealed that P^V–meso‐triarylcorroles showed a strong band at about 600 nm together with other bands, in contrast to P^V–porphyrins, which showed weak bands in the visible region. These compounds were easier to oxidize and more difficult to reduce compared to P^V–porphyrins. These compounds were brightly fluorescent, unlike the weakly fluorescent P^V–porphyrins, and the quantum yields for selected P^V–corroles were as high as Al^III and Ga^III corroles, which are the best known fluorescent compounds among oligopyrrolic macrocycles.     

Zum Einfluß der PR3‐Liganden auf Bildung und Eigenschaften der Phosphinophosphiniden‐Komplexe [{η2‐tBu2P–P}Pt(PR3)2] und [{η2‐tBu2P1–P2}Pt(P3R3)(P4R′3)]

Coordination Chemistry of P‐rich Phosphanes and Silylphosphanes XXI The Influence of the PR₃ Ligands on Formation and Properties of the Phosphinophosphinidene Complexes [{η²‐^tBu₂P–P}Pt(PR₃)₂] and [{η²‐^tBu₂P¹–P²}Pt(P³R₃)(P⁴R′₃)] (R₃P)₂PtCl₂ and C₂H₄ yield the compounds [{η²‐C₂H₄}Pt(PR₃)₂] (PR₃ = PMe₃, PEt₃, PPhEt₂, PPh₂Et, PPh₂Me, PPh₂ⁱPr, PPh₂^tBu and P(p‐Tol)₃); which react with ^tBu₂P–P=PMe^tBu₂ to give the phosphinophosphinidene complexes [{η²‐^tBu₂P–P}Pt(PMe₃)₂], [{η²‐^tBu₂P–P}Pt(PEt₃)₂], [{η²‐^tBu₂P–P}Pt(PPhEt₂)₂], [{η²‐^tBu₂P–P}Pt(PPh₂Et)₂], [{η²‐^tBu₂P–P}Pt(PPh₂Me)₂], [{η²‐^tBu₂P–P}Pt(PPh₂ⁱPr], [{η²‐^tBu₂P–P}Pt(PPh₂^tBu)₂] and [{η²‐^tBu₂P–P}Pt(P(p‐Tol)₃)₂]. [{η²‐^tBu₂P–P}Pt(PPh₃)₂] reacts with PMe₃ and PEt₃ as well as with ^tBu₂PMe, PⁱPr₃ and P(c‐Hex)₃ by substituting one PPh₃ ligand to give [{η²‐^tBu₂P¹–P²}Pt(P³Me₃)(P⁴Ph₃)], [{η²‐^tBu₂P¹–P²}Pt(P³Ph₃)(P⁴Me₃)], [{η²‐^tBu₂P¹–P²}Pt(P³Et₃)(P⁴Ph₃)], [{η²‐^tBu₂P¹–P²}Pt(P³Me^tBu₂)(P⁴Ph₃)], [{η²‐^tBu₂P¹–P²}Pt(P³ⁱPr₃)(P⁴Ph₃)] and [{η²‐^tBu₂P¹–P²}Pt(P³(c‐Hex)₃)(P⁴Ph₃)]. With ^tBu₂PMe, [{η²‐^tBu₂P–P}Pt(P(p‐Tol)₃)₂] forms [{η²‐^tBu₂P¹–P²}Pt(P³Me^tBu₂)(P⁴(p‐Tol)₃)]. The NMR data of the compounds are given and discussed with respect to the influence of the PR₃ ligands.     

Monte Carlo Simulation of Radiation Trapping in Hg–Ar Fluorescent Discharge Lamps

The line spectra of emitted resonance radiation from mercury and the effective decay rates of the Hg 6³P₁ and 6¹P₁ levels in mercury–argon discharges are simulated by a Monte Carlo method. The hyperfine splitting, the natural isotopic composition, collisional transfer of excitation, foreign gas collisions and quenching are considered to describe in detail the 253.7 nm and 184.9 nm lines. The calculations are performed for Hg vapor densities corresponding to coldest spot temperatures of 5–100°C, and discharge parameters typical for fluorescent lamp operation. The densities of the Hg 6³P₁ and 6¹P₁ levels are consistently estimated by means of a set of balance equations for the Hg 6³P₀, 6³P₁, 6³P₂, and 6¹P₁ excited states. The resulting uv radiation output of the discharge is then estimated for a tube radius of 18 mm, argon pressure of 400 Pa, discharge current 0.4 A, and wall temperatures of 20–80°C. The results obtained show a good agreement as compared with published experimental data.     

Synthesis and Characterization of Tetraphenylphosphonium Halochromates

Ion-associated halochromates (halo=F, Cl, Br) from tetraphenylphosphonium cation (Ph₄P⁺) are synthesized by stepwise solvent extraction technique and characterized based on XRD, spectral and thermal studies. The Ph₄P⁺CrO₃Br^- crystal is tetragonal with a=b=12.368 and c=7.511 ∮A. Thermal stabilities of these complexes are found to be decreasing in the order of Ph₄P⁺CrO₃F^-> Ph₄P⁺CrO₃Cl^-> Ph₄P⁺CrO₃Br^-. This revised version was published online in July 2006 with corrections to the Cover Date.     

Direct observation of geminate recombination within photochemically produced ion pairs in polar solutions

Pulsed laser excitation of pyrene (P)/N, N-diethylaniline (DEA) solutions in methanol at low temperatures leads to the generation of the P^? and DEA⁺ radical ions. A fast initial decay of the ions (τ_{$\text{1}\text{2}$} ≈ 37 nsec at ?40°C) is observed and is attributed to geminate recombination within the initially formed (²P^?…²DEA⁺) ion pair. The quenching of ¹P^*) by DEA is also associated with substantial intersystem crossing, yielding ³P^*. The data rule out both gemiate and non-geminate (homogeneous) inonic recombinations as sources for the initial yield of ³P^*, in keeping with a prompt triplet formation mechanism.     

The interaction of metastable Ne(3s 3 P 2,3 P 0) atoms with alkali atoms

Using crossed beams of alkali atoms (Li, Na, K) and state-selected metastable Ne(3s ³ P ₂,³ P ₀) atoms, we have measured the energy spectra of electrons resulting in the respective Penning ionization processes at thermal collision energies. The spectra are very different for Ne(³ P ₂) and Ne(³ P ₀): those for Ne(³ P ₂) are broad due to a strongly attractive interaction potential with a well depth of 798 (30) meV (Li), 672(20) meV (Na), and 561(20) meV (K), those for Ne(³ P ₀) are narrow and compatible with van der Waals type attraction (well depth <50 meV). The Ne(³ P ₂) cross section exceeds the one for Ne(³ P ₀) by about an order of magnitude.     

The Cobalt cyclo‐P4 Sandwich Complex and Its Role in the Formation of Polyphosphorus Compounds

A synthetic approach to the sandwich complex [Cp′′′Co(η⁴‐P₄)] ( 2 ) containing a cyclo‐P₄ ligand as an end‐deck was developed. Complex 2 is the missing homologue in the series of first‐row cyclo‐P_n sandwich complexes, and shows a unique tendency to dimerize in solution to form two isomeric P₈ complexes [(Cp′′′Co)₂(μ,η⁴:η²:η¹‐P₈)] ( 3 and 4 ). Reactivity studies indicate that 2 and 3 react with further [Cp′′′Co] fragments to give [(Cp′′′Co)₂(μ,η²:η²‐P₂)₂] ( 5 ) and [(Cp′′′Co)₃P₈] ( 6 ), respectively. Furthermore, complexes 2 , 3 , and 4 thermally decompose forming 5 , 6 , and the P₁₂ complex [(Cp′′′Co)₃P₁₂] ( 7 ). DFT calculations on the P₄ activation process suggest a η³‐P₄ Co complex as the key intermediate in the synthesis of 2 as well as in the formation of larger polyphosphorus complexes via a unique oligomerization pathway.