The Influence of Phosphane Ligands on the Versatility of Ruthenium–Indenylidene Complexes in Metathesis

Abstract

The aim of the present study is to develop readily available and stable pre-catalysts that could be easily prepared on large scale from simple starting materials. Based on the hypothesis that substitution of classical PCy(3) with phosphanes of varying electron-donating properties could be a straightforward manner to improve catalytic activity, a methodical study dealing with the effect of phosphane fine-tuning in ruthenium-indenylidene catalysts was performed. Challenged to establish how the electronic properties of para-substituted phosphane ligands translate into catalyst activity, the versatile behaviour of these new ruthenium-indenylidene complexes was investigated for a number of metathesis reactions.

Halide exchanged Hoveyda-type complexes in olefin metathesis

“…Polymers made of 4 and 5 are not prone to backbiting, i.e., no secondary metathesis reaction affects the double bonds of the formed polymer. Therefore the average number molecular weight ( M n ) can be used to establish an indirect, qualitative comparison of the ratio of initiation rate to propagation rate ( k i / k p ) of a given initiator and monomer combination [30]. Polymers made with M2 and M31 were used for further comparison.…”

Initiation efficacy of halo-chelated cis-dichloro-configured ruthenium-based second-generation benzylidene complexes in ring-opening metathesis polymerization

“…Table 1, entry 1). Those values are typical for a fast and complete initiation [19][20][21][22][23][24]. In contrast, slowly initiating M2 gave, under the same conditions, a polymer characterized by an M n value of Fig.…”

“…Additionally, two reference initiators, namely M31 and M2 were used for comparison. Compound M31 is a fast and fully initiating species allowing for controlled ROMP at room temperature in CH 2 Cl 2 (or toluene) [19][20][21][22][23][24][25], while M2 is an example for a rather slowly initiating initiator [19][20][21][22][23][24]. Accordingly, initiation of the polymerization of 9 with M31 at 25°C in CH 2 Cl 2 released a polymer characterized by an average number molecular mass (M n ) of 54,000 g/mol and a polydispersity index (PDI) of 1.08 (cf.…”

“…Br Cl mass distributions are, above all, only dependent on the concentration of the actual active 14 electron species in the reaction mixture [19][20][21][22][23][24].…”

Cyclic(alkyl)(amino)carbenes and the Research Prospect in Olefin Metathesis Reaction

“…再以油酸 甲酯 36 的乙烯分解反应为例(Eq. 6) [34] , Grubbs 二代催化 剂 3 和 25 对端烯 37 和 38 的选择性也较差(分别为 44% 和 33%) [33] 不可忽视的作用, 不同的膦配体带来的的催化效果也不 同 [36] . …”