Synthesis and x-ray crystal structure oftrans-diaquabis (4-morpholino) acetatocopper (II)

Summary An efficient procedure for the synthesis of the potassium salts of (4-morpholino)acetic acid, HL, and its -substituted derivatives is described. The title complex has been prepared and characterized by x-ray crystallography:a=8.505(2),b= 7.901(1),c=12.253(2) Å, =110.48(1)°, space groupP2₁/c,Z = 2, R_F=0.038 for 2300 observed MoK data. Hydrogen bonds link the centrosymmetrictrans-octahedral bis-chelated CuL₂(H₂O)₂ moieties into layers parallel to (100) in the crystal lattice.     

On braid groups

A dissertation in the Department of Mathematics submitted to the Faculty of the Graduate School of Arts and Science in partial fulfillment of the requirements for the degree of Doctor of Philosophy at New York University.     

Crystal and molecular structure of bis(cyclopentadienyl)tungsten tetrasulphide

The crystal and molecular structure of bis(cyclopentadienyl)tungsten tetrasulphide, (C₅H₅)₂WS₄, has been determined from three-dimensional X-ray data collected by counter techniques. The coordination about the tungsten atom, consisting of the two terminal sulfur atoms of the tetrasulphide chain and the ring centroids of the two cyclopentadienyl rings, may be described as a distorted tetrahedron. The inner S-S bond distance is found to be somewhat shorter than the outer two S-S bond distances in the tetrasulphide chain. The substance crystallizes in the monoclinic space groupP2₁/n witha = 11·242(3),b = 12·154(5),c = 8·790(2) Å and = 92·93(3) °. The structure was refined by least-squares techniques using 1581 independent reflections for whichFsk0/2 > 2(Fsk0/2), and the refinement converged at a conventionalR factor (onF) of 4·5 %.We wish to thank Dr. H. Köpf (Würzburg) for the gift of the crystals and the U.S. Atomic Energy Commission for financial support.     

Crystal and molecular structure of bis(tetramethylammonium) di(π-(1)-2-thiollyl)iron(II)

The crystal and molecular structure of bis(tetramethylammonium)di(-(1)-2-thiollyl)iron(II), C₈H₄₄B₂₀FeN₂S₂, has been determined from three-dimensional X-ray data collected by counter techniques. The material crystallizes in the orthorhombic system: space groupIbam, z=4, a=15·585(5), b=12·324(4), and c=14·806(6) Å. The B₁₀H₁₀S^2– moiety is an icosahedron with the sulphur atom and four boron atoms forming that part of the cage which is within bonding distance of the iron. The sulphur atom and one boron atom are disordered. The structure was solved by standard techniques and the least squares refinement, using 969 independent reflexions for whichF ₀ ² 3(F ₀ ²), converged to a conventionalR factor (onF) of 4·2%.No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, microfilming, recording or otherwise, without written permission of Plenum Publishing Company Limited.National Lending Library Supplementary Publication No. 60063 contains 2 pages of structure tables on 1 microfiche.     

Nucleophilic displacement of aromatic fluorine. Part V. Use of nitrogen heterocycles as nucleophiles

The scope of the nucleophilic displacement of aromatic halogens on 1,4-benzodiazepine precursors by the anions of pyrroles, pyrazoles and imidazoles was studied both with and without electron-withdrawing substitutents on the heterocyclic nucleophiles. Some of the products proved to be useful intermediates for the synthesis of novel fused 1,4-benzodiazepines.     

Perceptuomotor bias in the imitation of steady-state vowels

Previous studies suggest that speakers are systematically inaccurate, or biased, when imitating self-produced vowels. The direction of these biases in formant space and their variation may offer clues about the organization of the vowel perceptual space. To examine these patterns, three male speakers were asked to imitate 45 self-produced vowels that were systematically distributed in F1/F2 space. All three speakers showed imitation bias, and the bias magnitudes were significantly larger than those predicted by a model of articulatory noise. Each speaker showed a different pattern of bias directions, but the pattern was unrelated to the locations of prototypical vowels produced by that speaker. However, there were substantial quantitative regularities: (1) The distribution of imitation variability and bias magnitudes were similar for all speakers, (2) the imitation variability was independent of the bias magnitudes, and (3) the imitation variability (a production measure) was commensurate with the formant discrimination limen (a perceptual measure). These results indicate that there is additive Gaussian noise in the imitation process that independently affects each formant and that there are speaker-dependent and potentially nonlinguistic biases in vowel perception and production.