Preparation, Crystal Structure, Vibrational Spectra, and Thermal Behavior of Tl 2 H 2 P 2 O 6 and Tl 4 P 2 O 6

The new thallium(I) salts, Tl 2 H 2 P 2 O 6 ( 1 ) and Tl 4 P 2 O 6 ( 2 ), were prepared and structurally characterized by single‐crystal X‐ray diffraction. Compound 1 crystallizes in the monoclinic space group P 2 1 / c and compound 2 in the orthorhombic space group Pbca . Both structures feature channels occupied by the lone electron pairs of Tl + cations. Furthermore, those are built up by discrete [H 2 P 2 O 6 ] 2– for compound 1 and [P 2 O 6 ] 4– units for 2 in staggered conformation for the P 2 O 6 skeleton and the thallium cations. In Tl 2 H 2 P 2 O 6 ( 1 ) the hydrogen atoms of the [H 2 P 2 O 6 ] 2– ion are in a “ trans‐trans ” conformation. The O ··· H–O hydrogen bonds between the [H 2 P 2 O 6 ] 2– groups consolidate the structure 1 into a three‐dimensional network. FT‐IR/FIR and FT‐Raman spectra of the crystalline title compounds were recorded and a complete assignment for the P 2 O 6 4– modes is proposed. The phase purity of 1 was verified by powder diffraction measurements.