Synthese und Kristallstrukturanalyse von Undecacarbonyl- (μ-trifluormethylisocyanid)trieisen, Fe3(μ-CNCF3)(CO)11 / Synthesis and Crystal Structure Determination of Undecacarbonyl(μ-trifluoromethylisocyanide)triiron, Fe3(μ-CNCF3)(CO)11