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Alkyl(amino)‐ and Alkyl(chloro)phosphanyl‐Substituted Cyclopentadienyl Complexes of Titanium and Zirconium
Author(s) -
Kotov Vasily V.,
Avtomonov Evgeni V.,
Sundermeyer Jörg,
Harms Klaus,
Lemenovskii Dmitry A.
Publication year - 2002
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 - 10.1002/1099-0682(200203)2002:3<678::aid-ejic678>3.0.co;2-3
Subject(s) - chemistry , cyclopentadienyl complex , deprotonation , alkyl , dilithium , medicinal chemistry , zirconium , yield (engineering) , reagent , stereochemistry , inorganic chemistry , organic chemistry , catalysis , ion , materials science , metallurgy
Phosphanyl‐substituted cyclopentadienes of the type [R n Cp−PR(NR 1 R 2 /Cl)] ( 1 − 22 ) (R = Alk, Ar; R 1 , R 2 = H, Alk, Ar, SiR 3 ; R n Cp = t BuCp, Me 4 Cp, Ind, Me 6 Ind, Flu) can be synthesised by reaction of alkyldichlorophosphanes and alkyl(amino)chlorophosphanes with alkali metal cyclopentadienides. The method used is a general one and provides high isolated yields of the target compounds. The phosphanylcyclopentadienes can easily be deprotonated by strong bases (e.g. n BuLi, PhCH 2 K, Ph 2 CHK) and the potassium salts [R n Cp−PR(NR 1 R 2 )]K ( 25 − 28 ) are efficiently transmetallated by Me 3 SnCl. A subsequent reaction with TiCl 4 (L) 2 and ZrCl 4 (L) 2 (L = THF, tetrahydrothiophene, Me 3 P) affords new half‐sandwich complexes [{Me 4 Cp−P t Bu(NEt 2 )}TiCl 3 ] ( 36 ), [{Me 4 Cp−P t Bu(NEt 2 )}TiCl 3 ] ( 37 ) and [{ t BuCp−P t Bu(NEt 2 )}TiCl 3 ] ( 38 ) in moderate yields. The reaction of [ t BuCp−P t Bu(Cl)] ( 6 ) with TiCl 4 in the presence of Et 3 N at low temperature yields the half‐sandwich complex [{ t BuCp−P t Bu(Cl)}TiCl 3 ] ( 39 ) quantitatively; [(Cp−P t Bu(Cl)] 2 CMe 2 ] ( 11 ) reacts similarly and gives, dependent on the reagent ratio, either the homobimetallic derivative [{(Cp−P t Bu(Cl) 2 CMe 2 }{TiCl 3 } 2 ] ( 40 ) (1:2 ratio) or the ansa complex [{(Cp−P t Bu(Cl)] 2 CMe 2 }TiCl 2 ] ( 41 ) (1:1 ratio). The scope of this reaction could not be extended to sterically more demanding cyclopentadienyl derivatives. Treatment of [{ t BuCp−P t Bu(Cl)}TiCl 3 ] ( 39 ) by LiN(H) t Bu in the presence of Et 3 N leads to the formation of the constrained geometry complex [{ t BuCp−P t Bu(N t Bu)}TiCl 2 ] ( 42 ) in a high yield. All synthesised compounds were characterised by NMR spectroscopy, mass spectrometry and elemental analyses. The crystal structures of the ligand precursor [Me 6 Ind−P t Bu(NH t Bu)] ( 15 ) and that of [{Me 4 Cp−P t Bu(NEt 2 )}TiCl 3 ] ( 36 ) have been determined by X‐ray diffractometry. The complexes described in this work are active in the MAO‐mediated polymerisation of ethylene.