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Alkyne[hydrotris(pyrazolyl)borato]tantalum Complexes – An Ethyl Group is a Better α‐Agostic Donor Than a Methyl Group
Author(s) -
Hierso JeanCyrille,
Etienne Michel
Publication year - 2000
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/(sici)1099-0682(200005)2000:5<839::aid-ejic839>3.0.co;2-7
Subject(s) - methyllithium , chemistry , agostic interaction , alkyne , medicinal chemistry , moiety , tantalum , stereochemistry , organic chemistry , catalysis , metal
The synthesis of unprecedented alkyne hydrotris(3,5‐dimethylpyrazolyl)borato (Tp Me2 ) tantalum(III) complexes is reported. The parent dichloro complex Tp Me2 TaCl 2 (PhC≡ CCH 3 ) ( 2 ) is obtained from TaCl 3 (DME)(PhC≡CCH 3 ) and KTp Me2 . 2 reacts with methyllithium to give the dimethyl complex Tp Me2 Ta(CH 3 ) 2 (PhC≡CCH 3 ) ( 3 ) and with ethylmagnesium chloride to give the X‐ray characterized α‐agostic ethyl complex Tp Me2 Ta(Cl)(μ‐H–CHCH 3 )(PhC≡CCH 3 ) ( 4 ). Reaction of 4 with methyllithium generates the mixed methyl ethyl complex Tp Me2 Ta(CH 3 )(μ‐H–CHCH 3 )(PhC≡CCH 3 ) ( 5 ) in solution. Spectroscopic data indicate that 5 is α‐agostic at the ethyl group only.