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The Boratacyclooctatetraene Ligand: An Isoelectronic Trianionic Analogue of the Cyclooctatetraene Dianion
Author(s) -
Fang Xiangdong,
Woodmansee David,
Bu Xianhui,
Bazan Guillermo C.
Publication year - 2003
Publication title -
angewandte chemie international edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 1433-7851
DOI - 10.1002/anie.200351911
Subject(s) - cyclooctatetraene , chemistry , ligand (biochemistry) , transmetalation , regioselectivity , trimethylsilyl , steric effects , ring (chemistry) , yield (engineering) , electrophile , medicinal chemistry , acetylene , boron , stereochemistry , photochemistry , molecule , organic chemistry , materials science , catalysis , receptor , biochemistry , metallurgy
Expanding the ring : Acetylene inserts into one of the intracyclic BC bonds of [(C 5 H 5 BMe) 2 Ti(CO)] ( 1 ) to yield [(C 7 H 7 BMe)(C 5 H 5 BMe)Ti], which contains the formally trianionic methylboratacyclooctatetraene ligand and a boratabenzene ligand. Similarly, the reaction of 1 with trimethylsilylacetylene produces [(2‐SiMe 3 C 7 H 6 BMe)(C 5 H 5 BMe)Ti] ( 2 ), in which the trimethylsilyl group occupies the sterically more encumbering site adjacent to boron (C α ; see picture). The regiochemistry of 2 indicates that the transmetallation step may be viewed as an electrophilic attack of boron on the metal coordinated acetylene ligand.