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The crystal structure of meso-(2R,4r,6S)-2,4,6-heptanetriol as a model compound for syndiotactic poly(vinyl alcohol) was determined. The crystal belongs to a triclinic system with dimensions of a=10.950(9), b=9.904(11), c=14.199(13)Å, a=104.47(11), ß=114.10(8), and ?=70.34(7)°. The space groupis P1 and Dx=1.125, Dm=1.122Mgm-3, and Z=6. The final R factor was 0.080 for 3348 observed reflections. There are three crystallographically independent molecules in the unit cell. The seven carbon atoms of these three molecules have TTTT sequences and the OH groups form intermolecular hydrogen bonds. The best planes composed of seven carbon atoms of the three independent molecules are nearly parallel to each other and the molecular axes of the all molecules are nearly parallel to each other and point in the direction of the a-axis.

The crystal structure of DL-pentane-2,4-diol as a model compound of syndiotactic poly(vinyl alcohol) was determined. This crystal belongs to a monoclinic system with the dimensions of a=12.266(2), b=8.886(1), c=11.693(3)Å, and ß=92.94(4)°. The space group was P21/n and Dm=1.08, Dc=1.086 and Z=8. The final R factor was 0.083 for 1891 observed reflections. There are two crystallographically independent molecules in the unit cell. The five carbon atoms of these molecules have TT sequences and the OH groups form intermolecular hydrogen bonds. A structure analysis suggests that the conformation of syndiotactic poly(vinyl alcohol) may take TT sequences, the carbon chain has a planar zigzag form and the hydroxyl groups form intermolecular hydrogen bonds.

X-ray examination of crystals of α-amino isobutyric acid shows them to be built upon a composite monoclinic unit having a=10.59 kx, b=8.97 kx, c=11.34kx, and β=94°, containing eight molecules. The space group is C2/cwith all atoms being in the general positions with the following parameters which were determined by the three-dimensional Fourier analysis; nitrogen: x=0.154, y=0.100, z=0.388; carboxylic carbon: x=0.178, y=−0.025, z=0.199; α-carbon: x=0.212, y=−0.031, z=0.331; methyl carbon 1: x=0.355, =−0.027, z=0.365; methyl carbon 2: x=0.148, y=−0.167, z=0.382; oxygen 1: x=0.112, y=0.083, z=0.159; oxygen 2: x=0.224, y=−0.121, z=0.138. Bond distances are 1.26 and 1.20 kx. for carbon-oxygen, 1.52, 1.53 and 1.54 kx. for carbon-carbon and 1.49 kx. for carbon-nitrogen. There are observed a considerably close intramolecular approach between nitrogen and oxygen atoms and also close contact between two methyl groups.

Crystals of p, p’-dichlorodiphenoxy-1,2-ethane are monoclinic; their space group is P2/c, and they have 4 molecules in the cell with dimensions of:a=12.79, b=9.89, c=10.37Å; ß=98.2°Two crystallographically-independent molecules, which are slightly different in conformation, are located on the two-fold axis of the crystal. The OCH2CH2O groups are of the gauche form.

The crystals of meso-2,4-pentanediol borate are monoclinic with a space group of C2/c. There are eight molecules in the unit cell with dimensions of: a=15.36, b=13.53, c=7.68 Å, and β=113.3°. The crystal structure was determined by the X-ray method. The final discrepancy index is 0.121 for 1030 non-zero reflections. The molecule has a six-membered ring composed of one boron, three carbon, and two oxygen atoms. The borate group and the two carbon atoms of the pentane group are nearly co-planar. The five carbon atoms are also co-planar, and they are in transpositions. The molecule was proved to be of the mesotype.

The crystal structure of Dl-3-chloro-2,4-pentanediol has been determined by X-ray analysis. The crystal is triclinic, with dimensions of a=6.573, b=8.991, c=6.243 Å, α=80.18°, β=94.25°, and γ=102.87°. The five carbon atoms have a TT conformation, and the two OH groups have intermolecular hydrogen bondings, whose distances are 2.75 Å and 2.80 Å respectively.

The crystal structure of meso-(2S,4s,6R)-2,4,6-heptanetriol has been determined by means of X-ray methods. The crystal belongs to monoclinic system (space group Ic), with four molecules in a unit cell with dimensions of a=8.133, b=9.374, c=11.248 Å, and ß=93.24°. The structure was solved by three-dimensional Patterson and trial-and-error methods. The final Rfactor was 0.076. The molecule has the GTT\barG conformation, and all of the OH groups are linked together by intermolecular hydrogen bonds.