Dinitrogen Binding and Functionalization from a Low-Coordinate Alkynyliron Complex

Alkynyl complexes of low-coordinatetransition metalsoffer a stericallyopen environment and interesting bonding opportunities. Here, we explorethe capacity of iron(I) alkynyl complexes to bind N-2 andisolate a N-2 complex including its X-ray crystal structure.Silylation of the N-2 complex gives an isolable, formallyiron(IV) complex with a disilylhydrazido(2-) ligand, but naturalbond orbital analysis indicates that an iron(II) formulation is preferable.The structure of this compound is similar to an earlier reported phenylcomplex in which phenyl migration forms a new N-C bond, butthe alkynyl group does not migrate. DFT calculations are used to testthe possible reasons why the alkynyl is resistant to migration, andthese show that the large Fe-C bond energy in the alkynyl complexis a factor that could contribute to the lack of migration. An alkynyliron(I) complex binds N-2, and subsequentsilylation gives a surprisingly stable iron(IV) complex with a disilylhydrazido(2-)ligand.

Automated summary

In this study, the capability of iron(I) alkynyl complexes to bind N-2 was explored and a crystal structure of an iron(I) alkynyl complex with N-2 was obtained. It was further demonstrated that the alkynyl ligand is resistant to migration possibly due to the high Fe-C bond energy.