ISSN:
1089-7550
Source:
AIP Digital Archive
Topics:
Physics
Notes:
A new polymorph of 1,4-bis(2,2,6,6-tetramethyl-4-oxy-4-piperidyl-1-oxy)butadiyne has been prepared and characterized by x-ray diffraction, infrared and Raman spectroscopies, and magnetic susceptibility. Unlike the Pccn-α phase, the β phase belongs to the Pca21 space group [a=14.265(1) A(ring), b=8.079 (3) A(ring), and c=18.865(2) A(ring), V=2174.1 A(ring)3, Z=4, T=−100 °C, Ru=4.8%, Rw=5.0%). The C 3/4 C, CC–CC, and NO distances are 1.201, 1.391, and 1.293 A(ring), respectively. The only intermolecular interactions are 1.844-A(ring)–OH ⋅ ⋅ ⋅ ON hydrogen bonding interactions. The vibrations νOH,NH =3289, 3070, 3021, νNO(IR) =1341, and νC 3/4 C (Raman) =2236 cm−1 are present. The solid-state motif is that of pleated sheets. UV, electron beam, and γ-ray induced polymerization has not been achieved; however, thermal treatment turns the crystals black. Thermogravimetric analysis under nitrogen reveals an explosive decomposition at ∼140 °C. Between 2 and 300 K the susceptibility obeys the Curie–Weiss expression with aitch-theta=−2.75 K. The effective moment is 2.47μB per molecule which is consistent with two independent S= 1/2 spins per molecule. Upon thermal treatment (17 h at 90 °C) the resultant black material exhibits a reduced Curie–Weiss susceptibility of 1.12μB and aitch-theta=−2.87 K. Unlike the α phase evidence for ferromagnetic behavior has not been observed.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.340913
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