Halfsandwich tungsten complexes with a silanol-functionalized cyclopentadienyl ligand : synthesis and reactivity
Within the studies concerning metallo-silanols, halfsandwich-tungsten complexes have been silanol-functionalized at the cyclopentadienyl ligand. The stability and the condensation behavior have been investigated. Thus, it was shown that these complexes are stable enough for isolation but they are reactiv enough for time-effective condensation reactions with diverse chlorosilanes, chlorostannanes or metalhalogenides. These processes are characterized by an increased reactivity in contrast to metallo-silanols with a direct metal-bonded silanol group and proves that the separation of the silanol group has to be regarded as a successful manipulation. In addition, this modification allows a wide variation of the ligand sphere of the metal which was shown by H/Cl exchange, methylation, silylation or phosphine substitution. These changes evoke a small but significant influence on the silanol group. For example leads an introduced phosphine to an enhanced stability of the silanol function. A further separation of the silanol group from the metal by an additional alkylidene spacer leads to the complete lost of the stabilizing effect of the metal fragment and generates silanols which show a condensation behavior very similar to those of ordinary organosilanols.
Wolfram, Halbsandwich-Komplexe, Metallo-silanole, Tungsten, Halfsandwich-complexes, Metallo-silanols
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