Solid-phase synthesis of protonated nitrogen-containing heterocyclic compounds with the boron cluster anions starting from [Eu(H2O)9]2[B10Cl10]3: Synthesis, structure, and thermal properties of (НL)2[B10Cl10] (L = 7-amino-4-methylcoumarin or 1-ethyl-2-(4-methoxyphenyl) azobenzimidazole)

The paper proposes a new method for the synthesis of salts of a perchlorinated derivative of the decahydro- closo -decaborate anion with neutral N-containing organic bases L 1 and L 2 starting from previously prepared europium precursor [Eu(H 2 O) 9 ] 2 [B 10 Cl 10 ] 3 . Compound [Eu(H 2 O) 9 ] 2 [B 10 Cl 10 ] 3 was first synthesized and characterized by elemental analysis, X-ray powder diffraction, IR spectroscopy and its thermal properties were studied by TGA. The protonation of organic bases L was carried out in the solid phase in the presence of precursor [Eu(H 2 O) 9 ] 2 [B 10 Cl 10 ] 3 . For comparison, the reaction was carried out in solution: in the CH 3 CN/CF 3 COOH system and in an aqueous solution of (H 3 O) 2 [B 10 Cl 10 ] with pronounced acidic properties. The influence of reaction conditions on the composition and structure of the final products was analyzed. Salts of the composition (НL) 2 [B 10 Cl 10 ] (L is 1-ethyl-2-(4-methoxyphenyl)azobenzimidazole (L 1 ) and 7-amino-4-methylcoumarin (L 2 )) and (HL 2 )(H 9 O 4 ) [B 10 Cl 10 ] were synthesized and characterized by X-ray diffraction. The thermal properties of the obtained salts and ligand L 1 (C 16 H 16 N 4 O) were studied in air in the temperature range 20–600°С. Salt (НL) 2 [B 10 Cl 10 ] (L ​= ​1-ethyl-2-(4-methoxyphenyl)azobenzimidazole) was synthesized from europium salt [Eu(H 2 O) 9 ] 2 [B 10 Cl 10 ] 3 by solid-state synthesis and analyzed by X-ray diffraction. • Protonation of organic ligands L was studied in the presence of [B 10 Cl 10 ] 2– . • 7-amino-4-methylcoumarin and 1-ethyl-2-(4-methoxyphenyl) azobenzimidazole were used as L. • The CH 3 CN/CF 3 COOH system was used for solution experiments. • [Eu(H 2 O) 9 ] 2 [B 10 Cl 10 ] 3 was synthesized and used as precursor for solid state experiments. • Salts (НL) 2 [B 10 Cl 10 ] and (HL 2 )(H 9 O 4 ) [B 10 Cl 10 ] were synthesized and analyzed by X-ray diffraction.