Synthesis,Structures, and Thermal Stability of Dialkyl and Bis(amido) Zirconium(IV) Acen Complexes |
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| Authors: | Majeda Al Hareri Prof. Dr. David J. H. Emslie |
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| Affiliation: | Department of Chemistry, McMaster University, 1280 Main St West, Hamilton, ON L8S 4M1 Canada |
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| Abstract: | Reaction of one equivalent of H2(acen), H2(cis-Cyacen) or H2(trans-Cyacen) with [Zr(CH2SiMe3)4] at room temperature afforded [Zr(acen)(CH2SiMe3)2] ( 1 ), [Zr(cis-Cyacen)(CH2SiMe3)2] ( 2 ) or [Zr(trans-Cyacen)(CH2SiMe3)2] ( 3 ), respectively (acen=C2H4(NCMeCHC(O)Me)2; Cyacen=1,2-C6H10(NCMeCHC(O)Me)2). These alkyl compounds are trigonal prismatic in the solid state, and whereas 1 and 3 decomposed without sublimation above 120 °C (5–10 mTorr), 2 sublimed in >95 % yield at 85 °C (5–10 mTorr). However, heating solid 2 at 88 °C under static argon for 24 hours resulted in extensive decomposition to afford H2(cis-Cyacen) and SiMe4 as the soluble products. Compound 2 reacted cleanly with two equivalents of tBuOH to afford [Zr(cis-Cyacen)(OtBu)2] ( 4 ), but excess tBuOH caused both SiMe4 and H2(cis-Cyacen) elimination. The 1 : 1 reaction of H2(acen) with [Zr(NMeEt)4] did not proceed cleanly, and 8-coordinate [Zr(acen)2] ( 5 ) was identified as a by-product; this complex was isolated from the 2 : 1 reaction. A zirconium amido complex, [Zr(acen)(NMeEt)2] ( 6 ) was accessed via the reaction of 1 with two equiv. or excess HNMeEt, but decomposed readily in solution at room temperature. More sterically hindered [Zr(acen){N(SiMe3)2}2] ( 7 ) was synthesized via the reaction of [Zr(acen)Cl2] with two equivalents of Li{N(SiMe3)2}, but was also thermally unstable as a solid and in solution at room temperature. Compounds 1 – 3 , 5 and 7 were crystallographically characterized. |
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| Keywords: | Acen complexes Alkyl complexes Amido complexes Chelates Zirconium |
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