An-Najah Staff

A new class of supported carbonyl manganese catalyst was prepared by treating the dimeric decacarbonyldimanganese(0), Mn₂(CO)₁₀, with insoluble aminated poly(siloxane) surface. Solid state FT-IR spectra indicated that the supported catalyst is a dimeric complex that is substituted with two amine ligands, one at each Mn atom. The supported manganese complex was investigated as catalyst for the hydrosilylation reaction of terminal olefins. Contrary to the homogeneous Mn₂(CO)₁₀ catalytic system, the supported manganese complex was completely selective toward the hydrosilylation reaction with no detectable olefin isomerization or other side-reaction products. Furthermore, the catalyst was selective to produce the linear hydrosilylation product rather than the branched one. No lowering in catalyst activity due to the support was observed. A good proportion of the catalyst activity after separation and reuse was retained for at least four times. Highly reproducible catalytic activity measurements were obtained with catalytic samples taken from same prepared batch. Different prepared batches showed lower reproducibility. The effect of different reaction parameters, such as the solvent effect, the temperature effect, the concentration effect and the added-ligand effect have also been studied. Laine's kinetic studies indicated that the cluster remained intact during the reaction.

Ketimines (K1, K2) and aldimines (A1, A2, and A3) were prepared from unsubstituted acetophenone and/or benzaldehyde and primary amines (i-PrNH2, i-BuNH2 and t-BuNH2). These imines were reacted with Zeise’s salt (potassium ethenetrichloroplatinate(II)) to produce the respective complexes, namely, PtK1, PtK2, PtA1, PtA2, and PtA3. 1H, 13C, and 195Pt-chemical shifts of the ligands and their complexes were studied to investigate the nature and mode of isomerization around C N bond. The aldimines and their complexes were obtained as a single isomer. On the other hand, the ketimines and their complexes were obtained as a mixture of E/Z-isomers. It was found that the aldimine- and ketimine-platinum complexes undergo slow E/Z-isomerization in solution as evidenced from NMR spectra.

Dodecacarbonyltriruthenium(0), Ru3(CO)12, 1, has been chemically anchored to the aminated polysiloxane surface, 2. The resulting supported ruthenium complex, 3, was evaluated as catalyst for the olefin isomerization reactions. Contrary to its homogeneous catalyst counterpart, 1, the supported catalyst 3 showed exceptionally high selectivity towards 1-octene isomerization, and trans-2-octene was the sole product of the reaction mixture. The olefin isomerization reaction was markedly activated by the presence of the tertiary silane (EtO)3SiH. No hydrosilylation reaction products were detected. Preliminary kinetic study indicated catalysis by lower nuclearity catalytic species, where the cluster fragments during the reaction process. The effects of different reaction parameters on the rate of the reaction have been investigated.

Isomerization and hydrosilylation reactions of terminal olefins have been reported under thermal and photochemical conditions using Ru3 (C0) 12, 1, and HRu3 (CO)!!, 2,11 '0 In a very recent work, we reported E LI that 1 catalyses both Isomerization and hydrosilylation reactions of 1-octene (eq. 1). It has been found that the isomerization reaction occurs via lower nuclearity catalytic species that result from fragmentation of the mother cluster 1. Evidence in favour of concurrent cluster catalysis was also reported. On the other hand, the hydrosilylation reaction occurred via cluster catalysis at first and after some-time fragment catalysis occurred.

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The systems Ru₃(CO)₁₂·nL, (L = PPh₃, CH₃CN, (EtO)₃Si(CH₂)₃NH₂; n = 0–3, 15) have been employed as catalysts and/or catalyst precursors for thermal hydrogenation and isomerization reactions of 1-octene under moderate reaction conditions (1 atm at 70°C or below). In the hydrogenation reaction the system Ru₃(CO)₁₂/15CH₃CN showed the highest activity, with turnover numbers up to 1000. For this system the kinetics indicated that the hydrogenation occurs via a lower nuclearity catalytic species formed by fragmentation of the mother cluster. On the other hand the isomerization reaction occurs, after a 10–20 min induction period, by higher-nuclearity catalytic species. The isomerization gave trans-2-octene only, and none of the cis-isomer. The effects of other factors on the rates of hydrogenation and isomerization reactions are described.

A new class of supported carbonyl manganese catalyst was prepared by treating the dimeric decacarbonyldimanganese(0), Mn2(CO)10, with insoluble aminated poly(siloxane) surface. Solid state FT-IR spectra indicated that the supported catalyst is a dimeric complex that is substituted with two amine ligands, one at each Mn atom. The supported manganese complex was investigated as catalyst for the hydrosilylation reaction of terminal olefins. Contrary to the homogeneous Mn2(CO)10 catalytic system, the supported manganese complex was completely selective toward the hydrosilylation reaction with no detectable olefin isomerization or other side-reaction products. Furthermore, the catalyst was selective to produce the linear hydrosilylation product rather than the branched one. No lowering in catalyst activity due to the support was observed. A good proportion of the catalyst activity after separation and reuse was retained for at least four times. Highly reproducible catalytic activity measurements were obtained with catalytic samples taken from same prepared batch. Different prepared batches showed lower reproducibility. The effect of different reaction parameters, such as the solvent effect, the temperature effect, the concentration effect and the added-ligand effect have also been studied. Laine's kinetic studies indicated that the cluster remained intact during the reaction.