Can. J. Chem. 54, 3293 (1976). The infrared and Raman spectra of the four solid phases of malononitrile have been recorded. The crystal structures of these solids are now relatively well established from the present results and from previous X-ray and nuclear quadrupole resonance data. Phase I belongs to the P2,ln space group of the monoclinic system, with four molecules per unit cell. In phase 11, the molecules occupy two sets of general positions in a crystal of P2, symmetry. The molecular site symmetry is C, in phase I11 which is highly symmetric. The structure of the low-temperature metastable phase IV appears to be very similar to that of phase I. R. SAVOIE, R. BROUSSEAU et C. NOLIN. Can. J. Chem. 54, 3293 (1976) Nous avons enregistre les spectres infrarouges et Raman des quatre phases solides de la malononitrile. Nos resultats, ajoutes a ceux deja obtenus par diffraction des rayons-X et par resonance quadrupolaire, permettent de specifier assez bien les structures cristallines de ces solides. La phase I appartient au groupe P2,ln du systeme monoclinique, avec quatre molecules par maille elementaire. Dans la phase 11, les molecules occupent deux ensembles de positions generales dans un crystal de symetrie P2,. La symetrie des sites moleculaires est C, dans la phase 111 qui est hauternent syrnetrique. La structure de la phase metastable de basse temperature (IV) semble tres voisine de celle de la phase I.

The infrared, far-infrared, and Raman spectra of crystalline cyanoacetylene and its deutero, chloro, bromo, and iodo derivatives were found to be consistent with the known crystal structures of these compounds. However, no definite evidence could be obtained for the existence of a distinct lowtemperature crystalline modification of iodocyanoacetylene suggested earlier from X-ray diffraction data.

The presence of three fundamentals in the 545 cm-1 region of the vibrational spectrum of sulfuryl fluoride has been confirmed from the Raman spectrum of theliquid. Evidence for the occasional formation of a metastable crystalline form upon solidification of SOzFz has been gathered from the infrared study. The Raman investigation has also shown that the most stable crystalline solid (phase I) is seldom directly obtained upon freezing this compound. Both types of spectra indicate that the two stable crystalline phases (1 and 11) have well-ordered, although rather complex structures. The crystals are probably centrosymmetric in both cases, with at least 8 molecules located on general positions of the unit cell. The crystal system is other than triclinic or monoclinic. Cubic symmetry is further eliminated in the case of phase 11.Rkumk. La presence de trois fondamentales dans la region a 545 cm-l du spectre de vibration du fluorure de sulfuryle a tt6 confirm& a partir du spectre Raman du liquide. L'etude en infrarouge a permis de constater la formation occasionnelle d'une phase cristalline metastable de ce compose. Les rtsultats en Raman ont egalement indiqut que la phase cristalline stable (phase I) ne s'obtient generalement pas directernent lors de la solidification. Les deux types de spectres demontrent que les phases stables (I et 11) posddent une structure ordonnee, de nature complexe. Les cristaux sont probablement centro-symetriques dans chaque cas, avec un minimum de 8 molkules situks sur des position generales d'une maille klkmentaire de symetrie autre que triclinique ou monoclinique. De plus, le cristal I1 n'est pas cubique. Spectroscopy 2 (1974) 71-79. All Rights Reserved Copyright 0 1974 by D . Reidel Publishing Company, Dordrecht-Holland Journal of Raman