Relativistic all-electron molecular Hartree-Fock-Dirac-(Breit) calculations on CH4, SiH4, GeH4, SnH4, PbH4

Summary Results and details of molecular Fock-Dirac-(Breit) calculations on CH₄, SiH₄, GeH₄, SnH₄, and PbH₄ obtained with the MOLFDIR© program package are presented and compared with other calculations and experimental results. The relativistic ground state energies (including the Breit interaction) of the atoms C, Si, Ge, Sn, and Pb, necessary for reference purposes, have been calculated using a small relativistic CI. One of our findings is that for the heavier systems perturbation theory over-estimates the relativistic bond length contraction. The Breit interaction has only a small effect on the bond lengths.     

Stabilization Studies on Divalent Five‐Membered Rings C4H4C,C4H4Si,C4H4Ge,C4H4Sn,and C4H4Pb

Energy differences, ΔX_S‐t (X = E, H and G) (ΔX_S‐t = X_(singlet)‐X_(triplet)) between singlet (s) and triplet (t) states are calculated at B3LYP/6‐311++G (3df,2p). The DFT calculations show that the triplet state of C₄H₄C is a ground state with planar conformer respect to its corresponding nonplanar singlet state. Both singlet and triplet states of C₄H₄M (M = Si, Ge, Sn and Pb) have a planar conformer with the singlet ground state. Four isodesmic reactions are presented for determining the stability energies, SE. NICS calculations are carried out for C₄H₄M to determine the aromatic character.     

The crystal structure of LaIr4B4, ThOs4B4, ThIr4B4 (NdCo4B4-type) and URu4B4, UOs4B4 (LuRu4B4-type)

The crystal structure of LaIr₄B₄ has been refined from single crystal counter data. LaIr₄B₄ is tetragonal,P4₂/n,Z=2, isotypic with NdCo₄B₄, |F|/|F _o|=0.039 for 312 independent reflections [|F _o|>2 (F _o)]. ThIr₄B₄ and ThOs₄B₄ also belong to the NdCo₄B₄-type structure. URu₄B₄ and UOs₄B₄ were found to crystallize with LuRu₄B₄-type structure. The crystal chemistry of (RE)T ₄B₄-phases is discussed and simple geometric relations are shown to exist between them.Dedicated to Prof.B. T. Matthias in celebration of his 60th birthday.     

1, 4-氧硫杂萘-4, 4-二氧化物含氟衍生物的合成

以含氟的2-(2-氯-4-硝基苯磺酰基)-1-芳基乙酮为原料, 在K2CO3/TEBA/DMF体系中, 与烷基化试剂发生烷基化-环化反应。合成六种未经文献报道的1, 4-氧硫杂萘-4, 4-二氧化物的含氟衍生物,利用元素分析、IR、1H NMR、MS对其结构进行了表征。     

Water activity,osmotic and activity coefficients of aqueous solutions of Li2SO4, Na2SO4, K2SO4, (NH4)2SO4, MgSO4, MnSO4, NiSO4, CuSO4, and ZnSO4 at T=298.15 K

The water activities for aqueous solutions of Li₂SO₄(aq), Na₂SO₄(aq), K₂SO₄(aq), (NH₄)₂SO₄(aq), and sulphates MgSO₄(aq), MnSO₄(aq), NiSO₄(aq), CuSO₄(aq), and ZnSO₄(aq) were determined experimentally at a temperature of 298.15 K with a hygrometric method, at molalities in the range from 0.1 mol·kg⁻¹ to saturation. The osmotic coefficients are calculated from these results. The coefficients of Pitzer’s model was used to fit the osmotic coefficients for each salt solution. These parameters were used to predict solute activity coefficients for the salts studied.     

Photolyse von 2, 2, 4, 4-Tetramethylcyclobutanon-Derivaten

The photochemical reactions of the 2, 2, 4, 4-tetramethylcyclobutanones 1–6 carrying various substituents in 3-position were investigated. The major reaction in alcoholic solution or in the presence of other protic compounds was the formation of the semicyclic acetals 7–12 . Parallel to this reaction decarbonylation occurred, leading to stable cyclopropane derivatives in some cases, depending on the substituents present. Cyclopropanes with an exocyclic double bond underwent ring opening easily or, in case of an exocyclic carbon-nitrogen double bond, added alcohol, thus forming cyclopropane O, N-ketals. Alkyl-acyl biradicals are proposed as common intermediates for both photoreactions. Based on analogy to similar photoreactions reported in the literature, the formation of the semicyclic acetals is assumed to involve a carbene intermediate.     

The properties and some reactions of 4-oxo-1, 5-diazabicyclo[4, 4, 0]decane and 5-oxo-1, 4-diazabicyclo[4, 4, 0]decane

The chemical properties of 1,4- and 1,5-diazabicyclo[4, 4, 0]decanes and their 5- and 4-oxo derivatives, respectively, have been studied.     

Cross sections for rotational excitations of CH4, SiH4, GeH4, SnH4 and PbH4 by electron impact

We report differential and integral cross sections for rotational excitation of XH₄ molecules (X: C, Si, Ge, Sn, Pb) from 7.5–30 eV by electron impact. These cross sections were derived from fixed-nuclei scattering amplitudes (Bettega et al. 1995) obtained using the Schwinger Multichannel Method with Pseudopotentials (SMCPP) (Bettega et al. 1993). Our results represent the first rotational excitation cross sections for molecules as large as GeH₄, SnH₄ and PbH₄ using entirely ab initio procedures. The cross sections for CH₄ and SiH₄ obtained with pseudopotentials are in very good agreement with all-electron calculations and with other theoretical results. A comparison between our calculated cross sections and experimental data for CH₄ is in general encouraging, but some discrepancies remain. We found inelastic rotational cross sections and momentum transfer cross sections to be larger for SiH₄, GeH₄, SnH₄ and PbH₄ than for CH₄. We could explain this feature.     

Synthese der isomeren 3, 4-Dimethyl-4-phenyl-3, 4-dihydro-carbostyrile

Cyclisation of 2-methyl-3-phenyl-but-3-en-anilide (III) with polyphosphoric acid gave cis-3, 4-dimethyl-4-phenyl-3, 4-dihydro-carbostyril (VII) in 61% yield together with a small amount of 2, 3-dimethylindenone (VIII), whereas with AlCl₃ a phenyl group was split off to give 3, 4-dimethylcarbostyril (VI). The anilide III isomerises to cis- and trans-2, 3-dimethyl-cinnam-anilide (IV resp. V) under basic conditions. The anilides IV and V gave only small yields of the dihydrocarbostyril VII with polyphosphoric acid. Chlorination of VII in position 3 using PCl₅ yielded IX which, on splitting out HCl, gave 3-methylene-4-methyl-4-phenyl-3, 4-dihydro-carbostyril (X). X was converted to trans-3, 4-dimethyl-4-phenyl-3, 4-dihydro-carbostyril (XI) by catalytic hydrogenation.     

Ternary metal borides [La,Ce,Pr,Nd,Sm] Os4B4 and [Y,La,Ce,Pr,Nd,Sm,Gd,Tb] Ir4B4 with NdCo4B4-type structure

New ternary metal borides with compositionR. E. T ₄B₄ (R. E.=rare earth metal,T=transition metal) have been synthesized within the systems [La,Ce,Pr,Nd,Sm]–Os–B and [Y, La, Ce, Pr, Nd, Sm, Gd, Tb]–Ir–B. All compounds were found to be crystallizing with NdCo₄B₄-type structure. Magnetic measurements (80–300 K,Curie-Weiss behaviour, _p ~ 16K and µ_eff=9.94µ_B for TbIr₄B₄) indicate Y andR. E. elements (except Ce) to be trivalent in these compounds. The crystal chemistry of the isotypic series [Y,R. E.] [Os,Ir]₄B₄ is discussed.

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Ternäre Metallboride. [La,Ce,Pr,Nd,Sm] Os₄B₄ und [Y,La,Ce,Pr,Nd,Sm,Gd,Tb] Ir₄B₄ mit NdCo₄B₄-Struktur

Zusammenfassung Es wurden neue Metallboride der ZusammensetzungR. E. T ₄B₄ (R. E.=Seltenerdmetall,T=Übergangsmetall) innerhalb der Systeme [La,Ce, Pr,Nd,Sm]–Os–B und [Y,La,Ce,Pr,Nd,Sm,Gd,Tb]–Ir–B hergestellt. Alle Verbindungen kristallisieren entsprechend dem NdCo₄B₄-Typ. Magnetische Messungen (80–300K,Curie-Weiss-Verhalten, _p ~ 16K und µ_eff=9.94µ_B für TbIr₄B₄) zeigen an daß Y und dieR. E.-Elemente (ausgenommen Ce) in diesen Verbindungen trivalent sind. Die Kristallchemie der isotypen [Y,R. E.][Os,Ir]₄B₄-Verbindungen wird diskutiert.

     

Infrared absorption spectra and structure of 1, 1, 4, 4-tetrasubstituted 1, 4-disilacyclohexanes

The IR absorption spectra of 1,1,4,4-tetramethyl- and 1,1,4,4-tetraphenyl-1,4-disilacyclohexanes have been studied. The group spectral analysis of these compounds shows that the silicon atoms have barene properties. The presence at about 980 cm^–1 of one strong band (and not two) of C-C stretching vibrations in agreement with the selection rules confirms the chair form of the heterocycle.     

SYNTHESIS OF 4,5-SECOCHOLESTANE AND 4-METHYL-4,5-SECOCHOLESTANE

The synthesis of 4,5-secocholestane and 4-methyl-4,5-secocholestane fromcholesterol are reported.     

Relativistic Jahn-Teller effects in the photoelectron spectra of tetrahedral P4, As4, Sb4, and Bi4

The group-V tetrahedral cluster cations P(4)(+), As(4)(+), Sb(4)(+), and Bi(4)(+) are known to exhibit exceptionally strong Jahn-Teller (JT) effects of electrostatic origin in their (2)E ground states and (2)T(2) excited states. It has been predicted that there exist, in addition, JT couplings of relativistic origin (arising from the spin-orbit (SO) operator) in (2)E and (2)T(2) states of tetrahedral systems, which should become relevant for the heavier elements. In the present work, the JT and SO couplings in the group-V tetramer cations have been analyzed with ab initio relativistic electronic structure calculations. The vibronic line spectra and the band shapes of the photoelectron spectra were simulated with time-dependent quantum wave-packet methods. The results provide insight into the interplay of electrostatic and relativistic JT couplings and SO splittings in the complex photoelectron spectra of these systems.     

Statistische Modellrechnungen an den Molekülen CH4, SiH4, GeH4, SnH4 und PbH4 nach der Einzentrenmethode

Zusammenfassung Mit einem Einzentren-Ansatz werden Bindungsabstände und Gesamtenergien der Moleküle CH₄, SiH₄, GeH₄, SnH₄ und PbH₄ berechnet. Die statistische Betrachtungsweise der Elektronen nach Gombás und Ladányi [1] wird mit der Edelgas-Modellvorstellung nach Hartmann und Gliemann [2] verknüpft. Die Ergebnisse liegen in guter Übereinstimmung mit den vorliegenden experimentellen Daten. Bindungsabstand und Gesamtenergie des Moleküls PbH₄ werden erstmals berechnet.

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Statistical OCE-calculations on the molecules CH₄, SiH₄, GeH₄, SnH₄ and PbH₄

OCE-calculations are reported for ground state energies and bond distances of the hydrides CH₄, SiH₄, GeH₄, SnH₄ and PbH₄. The statistical atom model (Gombás and Ladányi [1]) is connected with the noble gas model (Hartmann and Gliemann [2]). The results are in good agreement with known experimental values. Bond distance and ground state energy of PbH₄ are presented for the first time.

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Wir danken der DFG für die finanzielle Unterstützung dieser Arbeit.     

Thermal diffusion of dilute aqueous NH4Cl,Me4NCl,Et4NCl,n-Pr4NCl,andn-Bu4NCl solutions at 25°C

The Soret effect (thermal diffusion) of dilute aqueous solutions of NH₄Cl, Me₄NCl, Et₄NCl, n-Pr₄NCl, and n-Bu₄NCl has been investigated potentiometrically using the silver, silver chloride thermocell. The molar entropies (heats) of transport have been derived from the initial and final thermoelectric powers. The concentration dependence of the entropy of transport has been examined and the effect of the ionic size on the heat of transport is discussed. The molar entropy of tetrabutylammonium chloride exhibits a sharp minimum in the neighborhood of 0.002M, the reason of which is as yet unclear.     

1, 4-Cycloaddition of 4-Phenyl-l, 2, 4-Triazoline-3,5-Dione to 2-Vinylpyridines

The addition of 4-phenyl-1, 2, 4-triazoline-3, 5-dione (I) to the pseudodienic system of 2-vinylpyridines leads to a new heterocyclic system — triazolo[l, 2-]-5-azacinnoline. A second molecule of I undergoes further reaction of the substitutive addition type.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 702–705, May, 1976.     

2,2,4,4—四对羟甲基酚氧基—6,6—二苯基三聚磷腈的合成

通过Friedel－Crafts反应，将本基引入到六氯环三磷腈上，然后由亲核取代反应和氢化还原反应，合成了2，2，4，4-四对羟甲基酚氧基-6，6-二苯基三聚磷腈，探索了各步的合成、分离方法，并对化合物的结构进行了表征．