Synthesis And Property Study Of New Ru-Based Olefin Metathesis Complexes

Olefin metathesis is a unique carbon skeleton redistribution in which unsaturatedcarbon-carbon bonds are rearranged in the presence of metal carbene complexes. Itsadvantages are mild reaction condition and high yield and its success in organicsynthesis and materials chemistry has been driven by the development of increasinglyefficient catalysts. Ru-based catalysts have received considerable attention because oftheir tolerance to moisture and oxygen. In this paper, a series of new ruthenium olefinmetathesis catalysts with high catalytic activity and chemo-selectivity, thermalstability or recyclability were designed and synthesized.1) A two-core ruthenium carbene catalyst {[RuBr（=CHPCy₃）（PCy₃）]₂（μ-Cl）₃}⁺[BF₄]^-was designed and synthesized. The catalytic activity, chemo-selectivity andthermal stability were studied. The results showed that this complex is achemo-selective and thermal stable catalyst for ring closing metathesis ofunsubstituted terminal dienes. No isomerized byproduct was observed when thiscomplex was used as the catalyst at high temperature （100-137°C）. This studyalso provided an important model for the study of new ruthenium olefin metathes-is catalyst.2) A ionic two-core ruthenium carbene catalyst {[RuCl（=CHPCy₃）（PCy₃）]₂（μ-Cl）₃}⁺[HOB（C6F5）₃]-was synthesized and characterized by¹H-NMR,¹³C-NMR,¹⁹F-NMR,³¹P-NMR,¹¹B-NMR and ESI-MS. The catalytic activity, chemo-selectivity,thermal stability and recyclability were studied. The results showed that this complexis a chemo-selective and recyclable catalyst for ring closing metathesis ofunsubstituted terminal dienes. No isomerized byproduct was observed whenruthenium carbene catalyst was used as the catalyst at high temperature （100-137°C）.More importantly, this catalyst could form ionic liquid when contact with cyclohexane.Six recycles were achieved for ring-closing metathesis of the selected substrate.3) The catalytic activity for synthesized ruthenium carbyne catalyst [（IMesH₂）（Cl）₂（C₅H₅N）₂Ru≡CPh]⁺[I₃]^-was studied. The results showed that this complex hasa high catalytic activity for ring closing metathesis of terminal dienes and has a highconversion for cross metathesis of terminal dienes. Therefore, the ruthenium carbinecatalyst is an effective olefin metathesis catalyst.