Tetraphenylarsonium tetraiodothallate(III)

The As and Tl atoms in title compound, (C(24)H(20)As)[TlI(4)], sit on fourfold inversion centres, resulting in a [TlI(4)](-) anion with D(2d) symmetry and a Tl-I bond length of 2.7691 (3) A. The tetrahedral anion is tetragonally distorted, being flattened in the direction of the c axis of the tetragonal unit cell, so that the two unique I-Tl-I angles differ by about 9 degrees. In contrast, the cation has S(4) symmetry and the tetrahedral coordination geometry of the As atom is very slightly stretched in the direction of the c axis.