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Wismutverbindungen mit voluminösen, mehrfach alkylierten Cyclopentadienyl‐Liganden
Author(s) -
Sitzmann Helmut,
Wolmershäuser Gotthelf
Publication year - 1994
Publication title -
chemische berichte
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 0009-2940
DOI - 10.1002/cber.19941270802
Subject(s) - chemistry , cyclopentadienyl complex , bismuth , crystal structure , stereochemistry , crystallography , stoichiometry , ligand (biochemistry) , catalysis , organic chemistry , biochemistry , receptor
Bismuth Compounds with Crowded Multiply Alkylated Cyclopentadienyl Ligands Herrn Professor Helmut Werner zum 60. Geburtstag gewidmet. Bismuth complexes of alkylated cyclopentadienyl ligands are obtained in good yield on treating bismuth(III) halides with tetraisopropylcyclopentadienylsodium or 1,2,4‐tri‐ tert ‐butyl‐cyclopentadienyllithium. A 1:1 stoichiometric ratio gives the complexes [Cp 4i BiCl 2 ] ( 1 ), [Cp 3t BiCl 2 ] ( 2 ), and [Cp 4i BiI 2 ] ( 3 ) (Cp 4i = C 5 i Pr 4 H, Cp 3t = C 5 H 2 t Bu 3 ‐1,2,4). According to X‐ray crystal structure analyses, 1 and 3 display dimeric structures with two bridging and two terminal halogeno ligands and η 3 ‐coordination of the cyclopentadienyl rings. With half an equivalent of tetraisopropylcyclopentadienylsodium BiCl 3 forms [Cp 4i Bi 2 Cl 5 ] ( 4 ). An X‐ray crystal structure analysis of 3 reveals a central Bi 2 Cl 10 core of two edge‐sharing BiCl 6 octahedra coordinated to two Bi(η 5 ‐Cp 4i ) fragments generating a framework of two face‐sharing cubes. Reaction of two equivalents of 1,2,4‐tri‐ tert ‐butylcyclopentadienyllithium with BiCl 3 yields deep purple [Cp 3t 2 BiCl] ( 5 ), a bent sandwich complex with an η 3 ,η 2 ‐bonding mode of the cyclopentadienyl ligands. Attempted formation of the octaisopropyl analogue of 5 from BiCl 3 and two equivalents of tetraisopropylcyclo‐pentadienylsodium with elimination of propene gives [Cp 4i Cp 3i BiCl] ( 6 ) (Cp 3i = C 5 H 2 i Pr 3 ). Use of monodeuterated tetraisopropylcyclopentadienylsodium in the second substitution step gave pure [Cp 4i ([D 1 ]Cp 3i )BiCl] ([D 1 ] 6 ) proving the absence of ring exchange reactions under the reaction conditions employed and elimination of propene from the second incoming sterically crowded tetraisopropylcyclopentadienyl ring system. The importance of proper choice of solvent and reaction conditions on the formation of alkylated cyclopentadienyl bismuth derivatives is demonstrated by extensive formation of 1,1′,3,3′,5,5′‐hexa‐ tert ‐butyldihydrofulvalene ( 7 ) from 1,2,4‐tri‐ tert ‐butylcyclopentadienylsodium and BiCl 3 .