Synthesis of Rubidium and Cesium Tellurocarboxylates and an X-Ray Structural Analysis of Heavy Alkali Metal Monochalcogenocarboxylates

Article abstract of DOI:10.1246/bcsj.68.3507

A series of rubidium and cesium tellurocarboxylates (2 and 3) were synthesized from the reaction of O-trimethylsilyl tellurocarboxylates (1) with rubidium and cesium fluorides in moderate isolated yields and characterized by 1H, 13C, and 125Te NMR spectroscopy and X-ray diffraction.The carbon-oxygen distance <1.235(6) Angstroem> of the tellurocarboxyl group of crystalline cesium 2-methoxybenzenecarbotelluroate (3f) showed a typical value of the carbon-oxygen double bond.The crystal packing of 3f shows the possibility of an interaction between the cesium cation and the aromatic ring carbon.The thio- and selenocarboxyl groups of the corresponding sulfur and selenium isologues (4 and 5) also indicate a double bond <1.231(4) and 1.226(5) Angstroem> between the carbon and oxygen, respectively.The salts ( 2 and 3) readily react with iodomethane to afford the corresponding Te-methyl tellurocarboxylates in good yields.The reaction between 3 and tetramethylammonium chloride was found to give a novel quaternary ammonium salt (8) of tellurocarboxylic acid, where the dihedral angle between benzene ring and the tellurocarboxyl group of 8 is ca. 90 deg.Crystallographic data for 3f, 4, 5, and 8 are as follows. 3f: P2₁/n, a=7.182(2), b=12.161(5), c=12.151(3) Angstroem, β=92.57(2) deg, V=1060.2(6) Angstroem³, d_calcd=2.479 g cm^-3, Z=4, R=0.035, R_w=0.043. 4: Pbca, a=8.995(2), b=29.936(2), c=7.291(1) Angstroem, V=1963.3(5) Angstroem³, d_calcd=2.030 g cm^-3, Z=8, R=0.024, R_w=0.021. 5: Pbca, a=9.290(1), b=30.207(2), c=7.193(2) Angstroem, V=2018.5(3) Angstroem³, d_calcd=2.284 g cm^-3, Z=8, R=0.029, R_w=0.020. 8: P2₁2₁2₁, a=11.844(2), b=14.014(2), c=8.650(1) Angstroem, V=1435.8(3) Angstroem³, d_calcd=1.558 g cm^-3, Z=4, R=0.044, R_w=0.047.