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The ESR spectra of a TDAE 1 -C 2 60 single crystal show the existence of antiferromagnetic (AFM) correlations between the unpaired spins on neighboring C 2 60 ions along the c axis and spin canting which leads, below T c , to weak ferromagnetism along a direction perpendicular to the c axis. This suggests that a Dzyaloshinsky-Moriya type mechanism is responsible for ferromagnetic ordering rather than itinerant ferromagnetism. The incomplete orientational ordering of the C 2 60 ions leads to a distribution of exchange coupling constants resulting in spin-glass type behavior which coexists with long range ferromagnetic ordering below T c . The observation of AFM correlations may help to understand why the same basic molecule C 60 can support such different phenomena as ferromagnetism (in TDAE-C 60 ) and superconductivity (in, e.g., K 3 C 60 ).

Precision neutron diffraction structure determination of protein and nucleic acid components. XVII. Molecular and crystal structure of the amino acid glycine hydrochloride Precision neutron diffraction structure determination of protein and nucleic acid components. XII. A study of hydrogen bonding in the purinepyrimidine base pair 9methyladenine · 1methylthymine J. Chem. Phys. 59, 915 (1973); 10.1063/1.1680114Precision neutron diffraction structure determination of protein and nucleic acid components. X. A comparison between the crystal and molecular structures of Ltyrosine and Ltyrosine hydrochloride A neutron diffraction study of L-valine . HCI has been carried out: space group P2 1 , a = 10.382(2), b =7.066(1), c =5.4407(9) A, 13=91.40(2)', Z =2. The structure has been refined by full-matrix least-squares techniques with anisotropic temperature factors for all atoms and with a Type II anisotropic extinction correction, leading to a conventional R value of 0.031. All hydrogen atoms have been located with a precision of 0.005 A. The structure is stabilized by a three-dimensional network of one O-H ... CI and three N-H '" CI hydrogen bonds, one for each hydrogen atom that is expected to participate in hydrogen bonding. The potential energy barrier for torsional motion of the ammonium group is estimated to be 6.4 kcal mole-I, or about 3 times larger than those found for the methyl groups. This difference reflects the effects of hydrogen bonding.

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