Monosodium l-Glutamate Pentahydrate

The title compound, Na + .C 5 H 8 NO 4 - .5H 2 O, crystallizes with two independent chemical units, composed of two L-glutamate anions (Glu A and Glu B), two Na + ions and ten water molecules, per asymmetric unit. Each Na + ion is coordinated by six water molecules in an octahedral arrangement. Strands of coordination octahedra sharing edges with neighbouring octahedra along the a axis are linked to one another through hydrogen bonds, forming extended layers parallel to the ac plane. Each of the Glu A and Glu B anions also forms hydrogen-bonded layers parallel to the ac plane on either side of the Na + -water coordination layer. The crystal packing is dominated by stacking of this triple-layer structure.