Measurement of the hyperfine field at Gd in ZrFe2 using the TDPAC method

A hyperfine field of 46.9±4.0 T at Gd nuclei in the intermetallic compound ZrFe₂ was measured by the time-differential perturbed angular correlation method. This result indicates an additional contribution of 81 T to that measured in gadolinium metal and suggests a similarity between the magnetic properties of ZrFe₂ and those of the rareearth intermetallic compounds.     

Optimal Parameter Choice in the {theta}-Method for Parabolic Equations

The general first-order method, known as the -method, is appliedto the semi-discrete form of a parabolic equation. It is shownthat to every required local accuracy there corresponds a valueof the parameter that is optimal in the sense of allowing thelargest step for which the error remains bounded below . Anasymptotic formula for in terms of is obtained, showing thatthe maximum step-size for the optimal -method is more than twiceas large as that for the Crank-Nicolson method. A numericalexample is given, showing good agreement between theory andpractice.     

The ν3 fundamental band of HDCO

The ν₃ fundamental band (CO stretch) of HDCO at 1724 cm^?1 has been studied using both conventional infrared absorption and CO laser Stark spectroscopy. In addition to the excited-state (v₃ = 1) rotational constants, improved constants for the ground state of HDCO have been obtained by combining previous microwave data with some infrared combination differences. The following constants were determined:

     

104.

The potential energy curve of the B ¹Π_u state of Na₂     

M. Lyyra  P.R. Bunker 《Chemical physics letters》1979,61(1):67-68

We have used the experimental energy levels of the B state of Na₂ to determine the shape of the potential curve. The potential curve obtained has been used to determine the Franck—Condon overlap of the continuum vibrational levels in the B state with bound levels in the ground electronic state.     

105.

Correlation between the n,π^* triplet energy of some acetophenones and the corresponding electroreduction potentials     

R.O Loutfy  R.O Loutfy 《Tetrahedron》1973,29(15):2251-2252

The half-wave reduction potentials, E_{$\text{1}\text{2}$}'s, of ten acetophenone derivatives have been determined in acetonitrile. A linear free-energy relationship was obtained between E_{$\text{1}\text{2}$} and the n,π^* triplet energy. This correlation enabled an estimate to be made of the n,π^* triplet energy of those acetophenones with π,π^* lowest triplet.     

106.

Extraktionsanalytische Verwendung des nicht sulfonierten Eriochromschwarz T     

H. Flaschka 《Mikrochimica acta》1956,44(4-6):784-789

Zusammenfassung Erio OS (die dem Eriochromschwarz T analoge Verbindung ohne Sulfogruppe) ist in organischen Solvenzien löslich und bildet mit einigen zweiwertigen Metallen sowie Indium und Gallium rot gefärbte, extrahierbare Komplexe. Die Komplexbildung kann selektiv durch Maskierungsmittel unterbunden werden. Es wird über einige spezifische Nachweise hoher Empfindlichkeit berichtet. Die extrahierten Metallkomplexe können in der organischen Phase photometrisch sehr genau bestimmt werden. Die Mehrzahl anderer Metallionen stört nicht, seibst bei Anwesenheit in größeren Mengen.

---

Summary Erio OS (which is analogous to Eriochrome black T without sulfonic groups) is soluble in organic liquids. It forms red extractable complexes with several bivalent metals and also indium and gallium. The complex formation can be selectively prevented by masking agents. Several specific tests of high sensitivity are described. The extractable metal complexes can be determined very accurately in the organic phase by photometry. Most of the other metal ions do not interfere, even if present in considerable proportions.

---

Résumé L'Erio OS (semblable au noir Eriochrome T, mais sans groupe sulfo) est soluble dans les solvants organiques; il donne lieu à la formation de complexes colorés en rouge avec les métaux bivalents, ainsi qu'avec l'Indium et le Gallium, et qui sont susceptibles d'être séparés par extraction. Il est possible d'inhiber sélectivement la formation de complexes à l'aide de réactifs masquants. On décrit quelques identifications spécifiques de grande sensibilité. Après leur extraction il est possible de doser les complexes métalliques dans la phase organique, par photométrie, avec une grande précision. La plupart des autres ions métalliques n'apportent aucune perturbation même s'ils sont présents en grandes quantités.

     

107.

Speciation of cyclo(Pro-Gly)<Subscript>3</Subscript> and its divalent metal-ion complexes by electrospray ionization mass spectrometry     

Ross AR  Luettgen SL 《Journal of the American Society for Mass Spectrometry》2005,16(9):1536-1544

Electrospray ionization mass spectrometry (ESI-MS) was used to study the binding of selected group II and divalent transition-metal ions by cyclo(Pro-Gly)3 (CPG3), a model ion carrier peptide. Metal salts (CatXn) were combined with the peptide (M) at a molar ratio of 1:10 M/Cat in aqueous solvents containing 50% vol/vol acetonitrile or methanol and 1 or 10 mM ammonium acetate (NH4Ac). Species detected include [M+H]+, [M+Cat-H]+, [M2+Cat]2+, [M+Cat+Ac]+, and [M+Cat+X]+. The relative stabilities of complexes formed with different cations (Mg2+, Ca2+, Sr2+, Mn2+, Co2+, Ni2+, Cu2+, and Zn2+) were determined from the abundance of 1:1 and 2:1 M/Cat species relative to that of the unbound peptide. The largest metal ions (Ca2+, Sr2+, and Mn2+) formed the most stable complexes. Reducing the buffer concentration increased the overall extent of metal binding. Results show that the binding specificity of CPG3 depends upon the size of the metal ion and its propensity for electrostatic interaction with oxygen atoms. Product ion tandem mass spectrometry of [M+H]+ and [M+Cu-H]+ confirmed the cyclic structure of the peptide, although the initial site(s) of metal attachment could not be determined.     

108.

A kinetic ESR study of the reaction of t-butylperoxy radicals with hexaphenylditin and hexaphenyldilead     

J.A. HowardE. Furimsky 《Journal of organometallic chemistry》1972

Absolute rate constants for the reaction of t-butylperoxy radicals with hexaphenylditin and hexaphenyldilead have been found to fit the equations log (k_p/M⁻¹·s⁻¹) = (5.5±0.15) − (3800±150)/Θ and log (k_p/M⁻¹·s⁻¹) (9.5±0.3) − (6000±250)/Θ, where Θ = 2.303 RT cal mol⁻¹, respectively.     

109.

Metal-templated diyne cyclodimerization and cyclotrimerization     

Martin-Redondo MP  Scoles L  Sterenberg BT  Udachin KA  Carty AJ 《Journal of the American Chemical Society》2005,127(14):5038-5039

Reaction of [Pt(CH3)2(COD)] (COD = 1,5-cyclooctadiene) with Ph2PCCCCPPh2 led to a mixture of [{Pt(CH3)2}2(mu-Ph2PC4PPh2)2] (1) and [{Pt(CH3)2}3(mu-Ph2PC4PPh2)3] (2). Reaction of [PtCl2(COD)] with Ph2PCCCCPPh2 led to a mixture of the thermally unstable compounds [{PtCl2}2(mu-Ph2PC4PPh2)2] (3) and [{PtCl2}3(mu-Ph2PC4PPh2)3] (4) which transform into [{PtMe2}2{mu-C8(PPh2)4}] (5) and [{PtMe2}3{mu3-C12(PPh2)6}] (6) containing 8-membered diene-diyne and 12-membered triene-triyne rings, respectively. Compound 2 can be converted to [{PtMe2}3{C12(PPh2)6}] (7) by heating with CuCl at 80 degrees C, while 1 can be heated without significant cycloaddition.     

110.

Generic implementation of semi-analytical CI gradients for NDDO-type methods     

S. Patchkovskii  A. Koslowski  W. Thiel 《Theoretical chemistry accounts》2005,114(1-3):84-89

Generic semi-analytical energy gradients are derived and implemented for NDDO-type methods, by using numerical integral and Fock matrix derivatives in the context of an otherwise analytical approach for configuration interaction (CI) and other non-variational treatments. The correctness, numerical precision, and performance of this hybrid approach are established through comparisons with fully numerical and fully analytical calculations. The semi-analytical evaluation of the CI gradient is generally much faster than the fully numerical computation, but somewhat slower than a fully analytical calculation, which however shows the same scaling behavior. It is the method of choice whenever a fully analytical CI gradient is not available due to the lack of analytical integral derivatives. The implementation is generic in the sense that it can easily be extended to any new NDDO-type Hamiltonian. The present development of a semi-analytical CI gradient will facilitate studies of electronically excited states with recently proposed NDDO methods that include orthogonalization corrections. Dedicated to Professor Karl Jug on the occasion of his 65th birthday     

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Constant	Ground state	$\text{v}{}_3\text{= 1}$ state	Units
$\text{ν}{}_0$		1724.267	cm?1
$\text{A}$	198 119.75	198 210.4	MHz
$\text{B}$	34 910.646	34 676.6	MHz
$\text{C}$	29 561.488	29 331.3	MHz
$\text{μ}{}_{\mathrm{a}}$	2.3302	2.3486	D
$\text{μ}{}_{\mathrm{b}}$	0.195	0.190	D

The potential energy curve of the B 1Πu state of Na2

We have used the experimental energy levels of the B state of Na₂ to determine the shape of the potential curve. The potential curve obtained has been used to determine the Franck—Condon overlap of the continuum vibrational levels in the B state with bound levels in the ground electronic state.     

Correlation between the n,π* triplet energy of some acetophenones and the corresponding electroreduction potentials

The half-wave reduction potentials, E_{$\text{1}\text{2}$}'s, of ten acetophenone derivatives have been determined in acetonitrile. A linear free-energy relationship was obtained between E_{$\text{1}\text{2}$} and the n,π^* triplet energy. This correlation enabled an estimate to be made of the n,π^* triplet energy of those acetophenones with π,π^* lowest triplet.     

Extraktionsanalytische Verwendung des nicht sulfonierten Eriochromschwarz T

Zusammenfassung Erio OS (die dem Eriochromschwarz T analoge Verbindung ohne Sulfogruppe) ist in organischen Solvenzien löslich und bildet mit einigen zweiwertigen Metallen sowie Indium und Gallium rot gefärbte, extrahierbare Komplexe. Die Komplexbildung kann selektiv durch Maskierungsmittel unterbunden werden. Es wird über einige spezifische Nachweise hoher Empfindlichkeit berichtet. Die extrahierten Metallkomplexe können in der organischen Phase photometrisch sehr genau bestimmt werden. Die Mehrzahl anderer Metallionen stört nicht, seibst bei Anwesenheit in größeren Mengen.

---

Summary Erio OS (which is analogous to Eriochrome black T without sulfonic groups) is soluble in organic liquids. It forms red extractable complexes with several bivalent metals and also indium and gallium. The complex formation can be selectively prevented by masking agents. Several specific tests of high sensitivity are described. The extractable metal complexes can be determined very accurately in the organic phase by photometry. Most of the other metal ions do not interfere, even if present in considerable proportions.

---

Résumé L'Erio OS (semblable au noir Eriochrome T, mais sans groupe sulfo) est soluble dans les solvants organiques; il donne lieu à la formation de complexes colorés en rouge avec les métaux bivalents, ainsi qu'avec l'Indium et le Gallium, et qui sont susceptibles d'être séparés par extraction. Il est possible d'inhiber sélectivement la formation de complexes à l'aide de réactifs masquants. On décrit quelques identifications spécifiques de grande sensibilité. Après leur extraction il est possible de doser les complexes métalliques dans la phase organique, par photométrie, avec une grande précision. La plupart des autres ions métalliques n'apportent aucune perturbation même s'ils sont présents en grandes quantités.

     

Speciation of cyclo(Pro-Gly)<Subscript>3</Subscript> and its divalent metal-ion complexes by electrospray ionization mass spectrometry

Electrospray ionization mass spectrometry (ESI-MS) was used to study the binding of selected group II and divalent transition-metal ions by cyclo(Pro-Gly)3 (CPG3), a model ion carrier peptide. Metal salts (CatXn) were combined with the peptide (M) at a molar ratio of 1:10 M/Cat in aqueous solvents containing 50% vol/vol acetonitrile or methanol and 1 or 10 mM ammonium acetate (NH4Ac). Species detected include [M+H]+, [M+Cat-H]+, [M2+Cat]2+, [M+Cat+Ac]+, and [M+Cat+X]+. The relative stabilities of complexes formed with different cations (Mg2+, Ca2+, Sr2+, Mn2+, Co2+, Ni2+, Cu2+, and Zn2+) were determined from the abundance of 1:1 and 2:1 M/Cat species relative to that of the unbound peptide. The largest metal ions (Ca2+, Sr2+, and Mn2+) formed the most stable complexes. Reducing the buffer concentration increased the overall extent of metal binding. Results show that the binding specificity of CPG3 depends upon the size of the metal ion and its propensity for electrostatic interaction with oxygen atoms. Product ion tandem mass spectrometry of [M+H]+ and [M+Cu-H]+ confirmed the cyclic structure of the peptide, although the initial site(s) of metal attachment could not be determined.     

A kinetic ESR study of the reaction of t-butylperoxy radicals with hexaphenylditin and hexaphenyldilead

Absolute rate constants for the reaction of t-butylperoxy radicals with hexaphenylditin and hexaphenyldilead have been found to fit the equations log (k_p/M⁻¹·s⁻¹) = (5.5±0.15) − (3800±150)/Θ and log (k_p/M⁻¹·s⁻¹) (9.5±0.3) − (6000±250)/Θ, where Θ = 2.303 RT cal mol⁻¹, respectively.     

Metal-templated diyne cyclodimerization and cyclotrimerization

Reaction of [Pt(CH3)2(COD)] (COD = 1,5-cyclooctadiene) with Ph2PCCCCPPh2 led to a mixture of [{Pt(CH3)2}2(mu-Ph2PC4PPh2)2] (1) and [{Pt(CH3)2}3(mu-Ph2PC4PPh2)3] (2). Reaction of [PtCl2(COD)] with Ph2PCCCCPPh2 led to a mixture of the thermally unstable compounds [{PtCl2}2(mu-Ph2PC4PPh2)2] (3) and [{PtCl2}3(mu-Ph2PC4PPh2)3] (4) which transform into [{PtMe2}2{mu-C8(PPh2)4}] (5) and [{PtMe2}3{mu3-C12(PPh2)6}] (6) containing 8-membered diene-diyne and 12-membered triene-triyne rings, respectively. Compound 2 can be converted to [{PtMe2}3{C12(PPh2)6}] (7) by heating with CuCl at 80 degrees C, while 1 can be heated without significant cycloaddition.     

Generic implementation of semi-analytical CI gradients for NDDO-type methods

Generic semi-analytical energy gradients are derived and implemented for NDDO-type methods, by using numerical integral and Fock matrix derivatives in the context of an otherwise analytical approach for configuration interaction (CI) and other non-variational treatments. The correctness, numerical precision, and performance of this hybrid approach are established through comparisons with fully numerical and fully analytical calculations. The semi-analytical evaluation of the CI gradient is generally much faster than the fully numerical computation, but somewhat slower than a fully analytical calculation, which however shows the same scaling behavior. It is the method of choice whenever a fully analytical CI gradient is not available due to the lack of analytical integral derivatives. The implementation is generic in the sense that it can easily be extended to any new NDDO-type Hamiltonian. The present development of a semi-analytical CI gradient will facilitate studies of electronically excited states with recently proposed NDDO methods that include orthogonalization corrections. Dedicated to Professor Karl Jug on the occasion of his 65th birthday