Structural and vibrational study a new potassium lithium dihydrogenphosphate KLi(H2PO4)2

• A new single crystal KLi(H2PO4)2 was synthesized by evaporation method.
• The structure of the compound was characterized using infrared and Raman spectroscopy.
• Bands attributed to the vibrational modes of H2PO4− units were identified.

The single crystal of potassium lithium dihydrogenphosphate KLi(H2PO4)2 (notated as KLDP) was synthesized at room temperature and its structure determined by single crystal X-ray diffraction. The compound was found to crystallize in the monoclinic system with space group P21/c (No.14) and the following parameters a = 7.5197(6), b = 12.8943(10) and c = 7.3900(6) Å, β = 98.477(3) °, Z = 4. This feature structure consists of LiO4 tetrahedra linked by corners with H2PO4 groups to form infinite layer running along the ab plane. In the interlayer, KO8 polyhedra form layers parallel to the same plane. In addition, Raman and infrared spectra were measured at room temperature, which confirm the presence of H2PO4, LiO4 groups and ABC bands in the unit cell. In fact, these fundamental vibrations were proposed by analogy with spectra of other phosphate-based hydrogen-bonded compounds.