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Synthesis, Structure and Chemistry of a Twisted Olefinic Bis‐didentate Proligand: 5,5′‐Bi‐5 H ‐cyclopenta[2,1‐ b : 3,4‐ b ′]dipyridinylidene
Author(s) -
Riklin Marianne,
von Zelewsky Alexander,
Bashall Alan,
McPartlin Mary,
Baysal Akin,
Connor Joseph A.,
Wallis John D.
Publication year - 1999
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/(sici)1522-2675(19991006)82:10<1666::aid-hlca1666>3.0.co;2-k
Subject(s) - chemistry , crystallography , stacking , molecule , hydrogen bond , stereochemistry , alkene , ligand (biochemistry) , organic chemistry , catalysis , biochemistry , receptor
The elusive chiral twisted alkene, 5,5′‐bi‐5 H ‐cyclopenta[2,1‐ b : 3,4‐ b ′]dipyridinylidene, known also as 9,9′‐bi‐4,5‐diazafluorenylidene (BDAF), has been prepared in racemic form from 9‐bromo‐4,5‐diazafluorene and from 9,9′‐bi‐4,5‐diazafluorenyl and fully characterised. X‐Ray measurements show that there is a twist of 37.8° about the double bond between the 4,5‐diazafluorenylidene units. A 1 : 1 charge‐transfer compound with 7,7,8,8‐tetracyanoquinodimethane (TCNQ) contains an unusual packing arrangement which is centred around the formation of spiral stacks. Each BDAF molecule contributes one 4,5‐diazofluorenylidene unit to the backbone of the stack, while the second half is involved in hydrogen‐bonding interactions and additional stacking with TCNQ. Examples of complexes containing the axially symmetric tetradentate ligand binding to one and to two metal ions, [M(bdaf)Cl 2 ] and [(MCl 2 ) 2 (bdaf)] (M=Co, Ni, Zn), are reported.