1952 Volume 25 Issue 3 Pages 192-195
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/c with 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.
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