Title

Synthesis, Characterization, and Ligand Substitution of [HFe₄(CO)₁₂BH]-: An Isoelectronic and Isoprotonic Inorganometallic Analogue of Hfe₄(CO)₁₂CH

Abstract

The anion [HFe4(CO)12BH]- has been prepared by the deprotonation of HFe4(CO)12BH2 and by the reaction of [HFe3(CO)9BH3]- with Fe2(CO)9. The latter constitutes an example of a high yield cluster expansion reaction that occurs with the concurrent production of Fe(CO)5 and H2. The most stable hydrogen locations on [HFe4(CO)12BH]- are analogous to those on the isoelectronic HFe4(CO)12CH molecule; however, hydrogen mobility on the cluster framework is more facile for the ferraborane than for the hydrocarbon analogue. Substitution of CO by PPhMe2 on [HFe4(CO)12BH]- occurs cleanly on a “wing-tip” iron via a second-order process involving a transient intermediate containing PPhMe2. Endo-hydrogen position is unaffected by monosubstitution, but the energy barrier associated with hydrogen exchange is increased. Replacement of a second CO by phosphine on the other “wing-tip” iron proceeds more slowly and results in the conversion of the FeHFe into a FeHB interaction, thereby producing a coordinated BH2 fragment. The effects that B-/C and CO/PPhMe2 interchanges have on stable hydrogen position and on endo-hydrogen mobilities are discussed within the framework of extended Hückel calculations. © 1987 American Chemical Society.

Department(s)

Chemistry

Document Type

Article - Journal

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 1987 American Chemical Society (ACS), All rights reserved.


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