189331-66-6Relevant academic research and scientific papers
Cationic zirconium dialkyl and alkyl complexes supported by DAC (deprotonated 4,13-diaza-18-crown-6) ligation
Lee, Lawrence,Berg, David J.,Bushnell, Gordon W.
, p. 2556 - 2561 (1997)
The synthesis, characterization, and reactivity of a series of neutral and cationic Zr alkyls supported by DAC (deprotonated 4,13-diaza-18-crown-6) ligation are reported. Reaction of H2DAC with Zr(CH2Ph)4 affords a 1:4 mixture of cis- and trans-Zr(DAC)(CH2Ph)2 (cis-/trans-1a). The pure isomers undergo slow cis-trans isomerization in solution to regenerate the 1:4 cis:trans equilibrium mixture. X-ray crystallographic results are reported for both cisand trans-1a. Reaction of Zr(CH2Ph)2Cl2 with H2DAC, followed by treatment with LiR (2 equiv), gives cis-Zr(DAC)R2 (R = CH2SiMe3, cis-1b; R = CH2CMe3, cis-1c) exclusively. Alkyl abstraction from cis- or trans-1a using B(C6F5)3 (1 equiv) produces the stable cation [Zr(DAC)(CH2Ph)]+[B(CH2Ph)(C6F 5)3]- (2a) as a yellow oil. NMR studies on 2a in CD2Cl2 show no evidence for η2-benzyl formation or anion coordination. Protonation of cis- or trans1a with [n-Bu3NH]+[BPh4]- similarly yields [Zr(DAC)(CH2Ph)]+[BPh4]- (2b). Cation 2a reacts with t-BuNC to form the vinyl amide complex [Zr(DAC){N(t-Bu)CH=CHPh}]+[B(CH2Ph)(C6F5) 3]- (3). p-Tolylacetylene undergoes catalytic dimerization to (Z)-1,4-di-p-tolyl-1-buten-3-yne in the presence of 2a.
