0000000000132357
AUTHOR
Stéphane Bredeau
Zirconocene [Cp2Zr] synthon and benzynezirconocene complexes as tools in main group element chemistry
Abstract Interactions between zirconocene or benzyne zirconocene and unsaturated species incorporating main group elements lead to a variety of new metallaheterocycles. Efficient new methodologies of regiospecific syntheses of mono-, bi-, or tricyclic systems incorporating phosphorus, nitrogen, selenium, antimony, germanium or tin are reported.
Versatile behavior of conjugated diynes with zirconocene reactive species
Thermal decomposition of Cp2ZrPh2 in the presence of the buta-1,3-diynes RC≡CC≡CR (R = Ph, SiMe3) can lead to seven- or five-membered metallacycles. In both cases a stable benzo-fused seven-membered zirconacyclocumulene arising from a 2-fold insertion of the triple bonds of the dialkyne in the in situ generated zirconocene benzyne is formed. In the case of Me3SiC≡CC≡CSiMe3 a second minor complex is isolated: a 3-alkynyl-substituted zirconaindene arising from a β monoinsertion of one acetylenic function of the conjugated diyne in the zirconocene benzyne. No stable 2-alkynyl-substituted zirconacycle was isolated. This α monoinsertion complex is an intermediate in the exchange of the metalated…
Coupling of Benzynezirconocene with 1,4-Diphenyl-1,3-butadiyne
The thermolysis of diphenylzirconocene in the presence of 1,4-diphenyl-1,3-butadiyne to yield the seven-membered zirconacyclocumulene 1 via the intermediacy of benzynezirconocene is described. This complex has been characterized by an X-ray diffraction study. Additionally, better knowledge of the bonding of the cumulene moiety was achieved by DFT calculations. Cleavage of the Zr−C bonds of 1 with methanol provided the corresponding butatriene 2.
Reactions of titanocene-bis(trimethylsilyl)ethyne complexes with diethynylsilane derivatives
Titanocene complexes [Ti(η 5 -C 5 H 5− n Me n ) 2 (η 2 -Me 3 SiCCSiMe 3 )] ( n =0, 4 and 5) react uniformly with siladiynes R 2 2 Si(CCR 1 ) 2 , where R 1 =Ph, and R 2 =Ph or Me, at elevated temperature in hydrocarbon solvents to give the corresponding silacyclobutene-annelated titanacyclobutene complexes, 3-bis(η 5 -cyclopentadienyl)titana-6-diorganylsilabicyclo[2.2.0]hexa-1(2),4(5)-dienes, [(η 5 -C 5 H 5− n Me n ) 2 Ti{R 1 2 C 4 (SiR 2 2 )}]. Products arising from [Ti(η 5 -C 5 H 5− n Me n ) 2 (η 2 -Me 3 SiCCSiMe 3 )] ( n =0, 2 (1,3-isomer), 4 and 5) and Me 2 Si(CCCMe 3 ) 2 vary with n : the non-methylated titanocene complex affords a mixture of an analogous silacyclobutene-annelated t…