Steroids and related studies. Part 60. Crystal and molecular structures of 17β-(2-hydroxyethyl)-3β-and 3α-pyrrolidino-17a-aza-D-homo-5-androstenes: HS-625 form 1, (3β-pyrrolidino) and HS-625 form 2 (mixed-3α and -3β-pyrrolidino epimers)

The crystal structures of two forms of 17-(2-hydroxyethyl)-3-pyrrolidino-17a-aza-D-homo-5-androstene (HS-625) are reported. In HS-625 (aqueous solvate) form 1, moleculeA, and HS-625 (anhydride) form 2, moleculeB, the pyrrolidine group is 3- substituted, while in HS-625 (anhydride) form 2, moleculeC has its pyrrolidine ring -substituted. HS-625 form 1 is orthorhombic, space groupP2₁2₁2₁, witha=7.089(4),b=11.502(6),c=28.975(16) Å,Z=4; form 2 is triclinic, space groupP1, witha=14.013(8),b=12.572(6),c=6.688(4) Å, =95.187(20), =103.491(21); =86.210(20)°,Z=2. MoleculesA andB have similar geometry, differences in moleculeC being related to strain caused by the unusual 3- ring substituent which also produces a pronounced kink in the backbone of the molecule. An unusual feature of the analysis of form 1 is the location of the water hydrogens in the difference electron density well above background. None of the OH hydrogens was located. Both structures are hydrogen bonded, but the pyrrolidine nitrogen N(31) in moleculeC is heavily congested and is unable to act as an acceptor. The hydroxyethyl side chain, important for activity, has a different conformation in the three molecules (t,g, t,-g, andt,t respectively).     

Topological charge quantization via path integration: An application of the Kustaanheimo-Stiefel transformation

Editorial note: The complete text of this paper, dedicated to Professor Asim O. Barut, will appear in the August 1993 issue ofFoundations of Physics.     

Complexes of ruthenium(II) and -(III) with dimethylsulphoxide—III. Bis-iodo-tetrakis- dimethylsulphoxide ruthenium(II) and some other iodo complexes of ruthenium(II)

The ruthenium(II) complex [RuI₂(Me₂SO)₄] was synthesized and characterized. The Me₂SO ligands are all S-bonded. Reactions of RuI₂(Me₂SO)₄ with ligands containing P, N and S donor atoms have been carried out and the complexes obtained were characterized using different physical methods. [RuI₂L₄] (L= CH₃CN, Me₂SO and py), [RuI₂(CH₃CN)₂(PPh₃)₂] and [RuI₂(CS)(PPh₃)₃] have been synthesized using RuI₃ as the source material and characterized as above.     

Pseudo Green's function theory for dilute alloys ofd-band metals

Summary The pseudo Green's function formalism for dilute alloys ofd-band metals is expanded in an overcomplete set of basis functions. Thed-band effects are included through the nonlocal effective impurity potential. The present formalism leads to an exact expression for the change in density of states caused by the introduction of an impurity. Thed-band contribution to the density of states is calculated for dilute copper alloys by using a simple model for the electronic structure of thed-band metals. It is found that thed-band contribution is responsible for the resonances and antiresonances in the density of states. A systematic study of the effects of the variation of impurity potential,d-resonance width andd-band energy on the density of states is carried out. The repulsive potential scatters thed states towards the higher energy which may lead to bound and virtual bound states in the vicinity of the Fermi level, while the attractive potential scatters thed states towards the lower energy which may lead to bound and virtual bound states towards the bottom of the conduction band. The results also predict that the probability of a bound and a virtual bound state is higher for dilute alloys of copper with a narrowd-band.

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Riassunto Si espande il formalismo di una pseudofunzione di Green per leghe diluite di metalli nella bandad in una sovracompleta serie di funzioni di base. Gli effetti della bandad sono inclusi attraverso il potenziale di impurità efficace non locale. Questo formalismo porta ad un'espressione esatta per il cambiamento di densità degli stati causato dall'introduzione di un'impurità. Il contributo della bandad alla densità degli stati è calcolato per leghe diluite di rame usando un modello semplice di struttura elettronica dei metalli della bandad. Si è trovato che il contributo della bandad è responsabile delle risonanze e delle autorisonanze nella densità degli stati. Si ottiene uno studio sistematico degli effetti della variazione del potenziale d'impurità, dell'ampiezza di risonanzad e dell'energia della bandad sulla densità degli stati. Il potenziale repulsivo diffonde gli statid verso energie più alte che possono portare a stati legati e virtualmente legati in vicinanza del livello di Fermi, mentre il potenziale di attrazione diffonde gli statid verso energie più basse che possono portare a stati legati e virtualmente legati verso il fondo della banda di conduzione. I risultati prevedono anche che la probabilità di stati legati e virtualmente legati sia più grande per leghe diluite con rame con una bandad stretta.

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Резюме Развивается формализм псевдо-гриновских функций для малолеги-рованных сплавовd-зонных металлов.d-зонные эффекты включаются через нело-кальный эффективный потенциал примеси. Предложенный формализм приводит к точному выражению для изменения в плотности состояний, которое обусловлено введением примеси. Вычисляет вкладd-зоны в плотность состояний для малолеги-рованных сплавов меди, используя простую модель для электронной структурыd-зонных металлов. Обнаружено, что вклад,d-зоны ответственен за резонансы и антирезонансы в плотности состояний. Проводится систематическое исследование влияния изменения потенциала примеси, шириныd-резонанса и энергииd-зоны на плотность состояний. Потенциал отталкивания при рассеянии переводитd-состояния в область боляших энергий, что может привести к связанным состояниям и виртуаль-ным связанным состояниям в окрестности уровня Ферми. Потенциал притяжения при рассеянии переводитd-состояния в область меньших энергий, что может привести к связанным состояниям и виртуальным связанным состояниям вблизи дна зоны проводимости. Полученные результаты предсказывают, что вероятность связанного и виртуального связанного состояния окзывается больше для малолег ированного сплава меди с узкойd-зоной.

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To speed up publication, the authors of this paper have agreed to not receive the proofs for correction.     

Degrees in a digraph whose nodes are graphs

By an f-graph we mean an unlabeled graph having no vertex of degree greater than f. Let D(n, f) denote the digraph whose node set is the set of f-graphs of order n and such that there is an arc from the node corresponding to graph H to the node corresponding to the graph K if and only if K is obtainable from H by the addition of a single edge. In earlier work, algorithms were developed which produce exact results about the structure of D(n, f), nevertheless many open problems remain. For example, the computation of the order and size of D(n, f) for a number of values of n and f have been obtained. Formulas for the order and size for f = 2 have also been derived. However, no closed form formulas have been determined for the order and size of D(n, f) for any value of f. Here we focus on questions concerning the degrees of the nodes in D(n,n − 1) and comment on related questions for D(n,f) for 2 f < n − 1.     

Dielectric constants,molar polarizations,and refractive indices for 2-butoxyethanol + hexane and +heptane at 30° and 40°C

Static dielectric constants and refractive indices of 2-butoxyethanol-n-hexane and-n-heptane mixtures were measured at 30 and 40°C and the various dielectric excess functionsviz. dielectric constants, molar polarizations, and orientation polarizations were evaluated. The excess dielectric constants and molar polarizations were found to be unsymmetrical and negative over the entire range of mole fraction. The trend in the variation of excess orientation polarization has shown three characteristic regions. The excess functions were smoothed through a variable degree polynomial. The results show the dominance of dipole-dipole interactions in the butoxyethanol deficient regions and weak specific interactions with unlike alkane molecules at higher butoxyethanol mole fractions.     

Theory of mass-yield distributions in “quasi-fission” reactions

A two-step process of “fission after a few nucleon transfer” is studied for the mass-yield distributions in the reaction of 605 MeV⁸⁴Kr ions with²³⁸U. The general agreement between the theory and experiment is qualitatively good. Based on the phenomenological considerations, sequential fission is also included partially. The transfer process is also shown to be given by the charge dispersion calculations.     

Charge distribution and covalency effects on mössbauer parameters in KFeS2

In this paper we report the effects of covalency on the Mössbauer Hyperfine parameters in KFeS₂. We emphasize the use of simple bonding schemes and models based on isomer shift calibration, point charge calculations and electronegativity differences in order to determine the ionic character of the atoms in the crystal. The previous Mossbauer spectroscopic work is also extended to liquid nitrogen temperature and it has been shown how the simple concept of electronegativity difference can also account for the order of magnitude of the measured saturation value of magnetic field.