Crystal structure of l-histidinium phosphite and a structure reinvestigation of the monoclinic form of l-histidine

M. T. Averbuch-Pouchot


l-histidinium phosphite, [C6N3O2H10]+·[HPO3H] is monoclinic P21 with crystal data: a = 8.497(7), b = 11.999(10), c = 4.967(3) Å, β = 104.15(6)°, V = 491(1) Å3 and Z = 2. The crystal structure was solved with a final R value of 0.030 for 1780 independent reflections. The organic and phosphoric entities build layers parallel to the (100) plane. The [HPO3H] groups, not held together by H-bonds, are linked by O–H⋯O and N–H⋯O bonds to the histidine groups. The latter are laced together by N–H⋯O bonds to form chains running parallel to b.

In addition to this study, the atomic arrangement of the monoclinic form of l-histidine was reinvestigated, this time with an untwinned crystal. The space group is P21 with a = 5.166(6), b = 7.385(5), c = 9.465(4) Å, β = 98.16(5)°, V = 357.4(9) Å3 and Z = 2. The new refinement, based on 1182 independent reflections, led to a final R value of 0.039. A description of the structure, including the H-bond scheme, is given. In addition to an improvement of the experimental accuracy, some H atoms, not found in the first study were located. The main structure is in general agreement with that from the previous investigation.

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Zeitschrift für Kristallographie – Crystalline Materials offers a place for researchers to present results of their crystallographic studies. The journal includes theoretical as well as experimental research. It publishes Original Papers, Letters and Review Articles in manifold areas of crystallography.