CRYSTAL-STRUCTURES OF PHENYLTRIMETHYLAMMONIUM SALTS OF TETRABROMOSELENATE(II) BROMIDE, 6H5(CH3)(3)N](2)[SEBR4]CENTER-DOT[C6H5(CH3)(3)N]BR AND A MIXED TETRA(BROMO CHLORO)SELENATE(II)/

The compounds were prepared from elemental selenium and halogen, and p henyltrimethylammonium halide. The crystal structures of [C6H5(CH3)(3) N](2)[SeBr4] . [C6H5(CH3)(3)N]Br (1) and [C6H5(CH3)(3)N](2)-[SeBr4-xCl x] . [C6H5(CH3)(3)N]Br1-yCly (2) have been determined by X-ray methods . The crystals are orthorhombic, space group P2(1)2(1)2(1) with Z=4 an d a=9.061(2), b=13.872(4), c=25.894(5) Angstrom for 1, and a=8.998(2), b=13.787(3), c=25.570(5) Angstrom for 2. The compounds have monomeric square-planar SeX42- anions and the Se-Br distances for 1 are in the range 2.547(1)-2.616(1) Angstrom.