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

Syntheses and Reactions of Iron Cluster Compounds with a μ 3 ;‐λ 2 ‐Coordinated Trifluoromethyl Isocyanide Ligand. Formation of an N ;‐(Trifluoromethylformimidoyl Ligand Pyrolysis of the iron clusters Fe 3 (CO) 10 (L)(μ 2 ‐CNCF 3 ) ( 1a – d ) [LP(OCH 3 ) 3 a , P(OC 2 H 5 ) 3 b , P (CH 3 ) 3 c , P(C 2 H 5 ) 3 d ] in n ‐heptane at 95°C results in the reversible elimination of two mol of carbon monoxide and formation of the cluster compounds Fe 3 (CO) 8 (μ 3 ;‐λ 2 ‐CNCF 3 )L ( 2a – d ). According to the crystal structure determination of 2a trifluoromethyl isocyanide acts as a μ 3 ;‐λ 2 ‐bridging ligand with its CN bond perpendicular to one iron‐iron edge. 2a reacts with molecular hydrogen to yield Fe 3 (CO) 8 (L)(μ 3 ;‐λ 2 ‐HCNCF 3 )(μ 2 ‐H) ( 3a ) containing a μ 3 ;‐λ 2 ;‐ N ;‐(trifluoromethyl)formimidoyl ligand. 3a exists as a mixture of three isomers. The isomerization of two of these isomers is studied by variable temperature 1 H‐, 19 F‐, and 31 P‐NMR spectroscopy. Reaction of 2a with NaBH 4 leads to the ionic cluster Na[Fe 3 (CO) 8 (L)(μ 3 ;‐λ 2 ‐HCNCF 3 )] ( 4a ), which yields 3a on protonation with trifluoroacetic acid.