Modellsysteme für die [NiFe]-Hydrogenase und Zinkkatalysatoren für die Hydrosilylierung [article]

Nicolas Alexander Marinos, Matthias Drieß, Technische Universität Berlin, Technische Universität Berlin
2011
In the first part of this work the preparation and characterization of heterobimetallic [FeNi] complexes as potential model systems for the [NiFe] hydrogenase were investigated. In the second part efficient zinc catalysts for the hydrosilylation of ketones in which the metal center is in a mixed hard and soft coordination sphere were introduced. Different iron and nickel precursors with bis(diphenylphosphino)methane- (dppm) and 3-(diphenylphosphino) propanole ligands (dpppOH) were prepared for
more » ... were prepared for the syntheses of [FeNi] complexes. The formation of heterobimetallic (µ-dppm-1kP,2kP')-[FeNi] complexes was proven from the reaction of dppm iron compounds 45 and 46 with tetracarbonyl nickel. 1,4-addition of the OH function of the dpppOH ligand to the silylene nickel complex 56 lead to the formation of the ionic [FeNi] complex 65 and to the neutral [FeNi] complex 66. Tri- and tetranuclear [FeNi] complexes were obtained by linear bridging of the metal centers with cyano ligands. Macro cyclic [Fe2Ni2] complexes [Fe(CpR)(CO)(µ-CN)2NiL]2 (R = H, 71; Me, 75) were formed by the reaction of K[Fe(CpR)(CN)2(CO)] (R = H, Me) with [NiL(µ-Br)2Li(thf)2]. Alternatively, compound 71 was isolated from the reaction of [FeCp(CN)(CO)2] with [(NiIL)2)(toluol)]. Compounds 71 and 75 were obtained as a mixture of the cis and trans isomers. Ring inversion and allogon isomerism were observed for the butterfly shaped structures of 71 and 75. The activation energy of the ring inversion was determined experimentally. The synthesis of the trinuclear [Fe2Ni] complex [{FeCp(CO)2(µ-CN)}2NiL]BPh4 78 succeded in reacting two equivalents of [FeCp(CN)(CO)2] with one equivalent of [NiL(µ-Br)2Li(thf)2] and NaBPh4. In the second part of this work diketo sulfides with a mixed hard and soft ligand sphere were used for the coordination with zinc. Reaction of the tert-butyl substituted ligand with dialkylzinc lead to the formation of monodeprotonated monoalkyl zinc complexes 89 and 90. These mononuclear complexes reacted with an excess of dialkylzinc to the trinucl [...]
doi:10.14279/depositonce-2709 fatcat:css5mu6nmvdr3cjqkj2seece4m