Low-valent iron(i) amido olefin complexes as promotors for dehydrogenation reactions.

FeI compounds including hydrogenases show remarkable properties and reactivities. Several iron(I) complexes have been established in stoichiometric reactions as model compounds for N2 or CO2 activation. The development of well-defined iron(I) complexes for catalytic transformations remains a challenge. The few examples include cross-coupling reactions, hydrogenations of terminal olefins, and azide functionalizations. Here the syntheses and properties of bimetallic complexes [MFeI(trop2dae)(solv)] (M=Na, solv=3 thf; M=Li, solv=2 Et2O; trop=5H-dibenzo[a,d]cyclo-hepten-5-yl, dae=(N-CH2-CH2-N) with a d7 Fe low-spin valence-electron configuration are reported. Both compounds promote the dehydrogenation of N,N-dimethylaminoborane, and the former is a precatalyst for the dehydrogenative alcoholysis of silanes. No indications for heterogeneous catalyses were found. High activities and complete conversions were observed particularly with [NaFeI(trop2dae)(thf)3].