Crystal structure of piezoelectric lithium formate monohydrate

Piezoelectric lithium formate monohydrate crystallizes in the orthorhombic system with a tetramolecular unit cell of dimensions a = 6.504 (10), b = 9.989 (10), c = 4.856 (5) Å in the space group Pbn21. The crystal structure has been solved by vector superposition methods and refined to an R value of 10.3 % for 331 observed reflections. The formate ion, the water-oxygen and the lithium ion lie in a plane approximately parallel to the (100) plane. The formate dimensions are: C-O(1): 1.213(12), C-O(2): 1.279(12) Å and O(1)-C-O(2): 125.8(9)° The lithium ion in the structure is tetrahedrally coordinated to oxygen atoms at a mean Li-O length of 1.95 Å. Neighbouring tetrahedra related by the 21, screw share a corner and form an infinite chain along the c axis. Two of the three hydrogen atoms have been located. The hydrogen bonding scheme is unambiguously fixed and results in the formation of an infinite chain of water-oxygens along the c axis. The vibration amplitudes of the atoms are maximum along the a axis.