Strukturen von Pentaarylbismut‐Verbindungen

Structures of Pentaarylbismuth Compounds Rose‐colored, dichroitic pentakis (4‐methylphenyl) bismuth has an intermediate structure between trigonal bipyramidal and square‐pyramidal. It cocrystallizes with (LiCl · 2 THF)2. The LiCl forms an almost regular rectangle with two short (195pm) and two long (235pm) bonds. Red Bi(4‐CH3C6H4)3(2,6‐F2C6 H3)2 is very similar to square pyramidal Bi(4‐C6H5)3 (2,6‐F2C6H3)2: The structural isomerism of yellow Bi(4‐CH3C6H4)3 (2‐FC6H4)2 (trigonal bipyramidal) and violet Bi (C6H5)3 (2‐FC6H4)2 (square pyramidal) is not found here. Orange red, dichroitic Bi(C6H5)3‐(C12H8) remains in a distorted square pyramidal structure in spite of the constraints of the 2,2′‐biphenylylene ring system. The square pyramidal geometry seems to dominate in bismuth chemistry of this type, in contrast to P, As, and Sb. However, the structure of (C6F5)3BiF2 shows an almost regular trigonal bipyramid, as expected. The latter cocrystallizes as (C6F5)3BiF2 · 2 Bi (C6F5)3, so the structure of Bi(C6F5)3 is elucidated also.