199677-24-2

Upstream product

• 174809-97-3 [(p-Bu(t)-calix[4]-(OMe)2(O)2)Zr(π(2),η(4)-butadiene)] 
• 501-65-5 diphenyl acetylene 

Relevant academic research and scientific papers

Zirconium-butadiene bonded over a planar set of oxygens derived from calix[4]arene and its behavior as a source of zirconium (II)

This report deals with the first examples of butadienes bonded to a Zr-O matrix provided by a calix[4]arene skeleton and their reactivity. The reaction of [{p-But-calix[4]-OMe)2-(O)2)ZrCl2], 2, with Mg(C4H6)(thf)2 and Mg(Ph2C4H4)(thf)3 led to [{p-But-calix[4]-(OMe)2(O)2}-Zr(η 4-C4H6)], 3, and [{p-But-calix[4]-(OMe)2(O)2}Zr(η 4-Ph2C4H4)], 4. The butadiene fragment exhibits a π2,η4 bonding mode, as shown by an X-ray analysis on both compounds. Extended Hu?ckel calculations confirmed the energetically preferred s-cis conformation and the π2,η4 bonding mode vs the σ2,π,η4 one. The parent compound 3 of this series behaves, however, both as a source of zirconium(II) in displacement reactions or as a dialkyl derivative of zirconium(IV) in insertion reactions. In the former class of transformations, the reaction of 3 with Ph2CO and PhCOCOPh led to the dioxo metallacycles [{p-But-calix[4]-(OMe)2(O)2}-Zr{-OC(Ph) 2-C(Ph)2O-}], 5, and [{p-But-calixt[4](OMe)2(O) 2}Zr{-OC(Ph)=C(Ph)O-})], 6, respectively. Butadiene was also displaced by diphenylacetylene leading to [{p-But-calix-[4]-(OMe)2(O)2}Zr(η 2-Ph2C2)], 7, and by a phenylnitrene source [PhN3] forming the dinuclear phenylimido-bridged complex [{p-But-calix[4]-(OMe)2(O)2}2Zr 2(μ-NPh)2], 8. Unlike at room temperature, Ph2CO reacted with 3 at low temperature without displacing the butadiene, but leading, instead, to the stepwise insertion of the ketone to form [{p-But-calix[4]-(OMe)2(O)2}Zr{CH 2CH=CHCH2C(Ph)2O}], 10, and [{p-But-calix[4](OMe)2(O)2}Zr{-OC(Ph) 2-CH2CH=CHCH2C(Ph)2O-}], 11. Using 2 mol of acetone, [{p-But-calix[4]-(OMe)2(O)2}Zr{-OC(Me) 2CH2CH=CHCH2C(Me)2O-}], 12, was obtained. MeCN and EtCN inserted in a single Zr-C bond (of a formal σ2,π,η4 structure) yielding [{p-But-calix[4]-(OMe)2(O)2}Zr{-CH 2CH=CHCH2C(Me)=N-}], 13, and [{p-But-calix[4](OMe)2(O)2}Zri{-CH 2CH=CHCH2-C(Et)=N-}], 14. ButNC engaged 3 in a multistep insertion reaction leading to [{p-But-calix[4]-(OMe)2(O)2}Zr{-(Bu t)NC(C4H6)C(C=NBut)N(Bu t)-}], 15, via a pathway which has been observed in the reaction of ButNC with dialkylzirconium calix[4]arene derivatives. The σ2 behavior of butadiene in 3 was further verified in the reaction with H2O to give [{p-But-calix[4]-(OMe)2(O)2}2Zr 2(μ-O)2], 9, and butenes.