Synthese und Reaktionen von Eisen‐Clustern mit μ 3 ;‐λ 2 ‐koordiniertem Trifluormethylisocyanid‐Liganden. Bildung eines N ;‐(Trifluormethyl)‐formimidoyl‐Liganden

Abstract

Syntheses and Reactions of Iron Cluster Compounds with a μ3;-λ2-Coordinated Trifluoromethyl Isocyanide Ligand. Formation of an N;-(Trifluoromethylformimidoyl Ligand Pyrolysis of the iron clusters Fe3(CO)10(L)(μ2-CNCF3) (1a – d) [LP(OCH3)3a, P(OC2H5)3b, P(CH3)3c, P(C2H5)3d] in n-heptane at 95°C results in the reversible elimination of two mol of carbon monoxide and formation of the cluster compounds Fe3(CO)8(μ3;-λ2-CNCF3)L (2a–d). According to the crystal structure determination of 2a trifluoromethyl isocyanide acts as a μ3;-λ2-bridging ligand with its CN bond perpendicular to one iron-iron edge. 2a reacts with molecular hydrogen to yield Fe3(CO)8(L)(μ3;-λ2-HCNCF3)(μ2-H) (3a) containing a μ3;-λ2;-N;-(trifluoromethyl)formimidoyl ligand. 3a exists as a mixture of three isomers. The isomerization of two of these isomers is studied by variable temperature 1H-, 19F-, and 31P-NMR spectroscopy. Reaction of 2a with NaBH4 leads to the ionic cluster Na[Fe3(CO)8(L)(μ3;-λ2-HCNCF3)] (4a), which yields 3a on protonation with trifluoroacetic acid.