Low energy electron-induced decomposition of (η5-Cp)Fe(CO)2Mn(CO)5, a potential bimetallic precursor for focused electron beam induced deposition of alloy structures

Abstract

The production of alloyed nanostructures presents a unique problem in focused electron beam induced deposition (FEBID). Deposition of such structures has historically involved the mixing of two or more precursor gases in situ or via multiple channel gas injection systems, thereby making the production of precise, reproducible alloy compositions difficult. Promising recent efforts to address this problem have involved the use of multi-centred, heterometallic FEBID precursor species. In this vein, we present here a study of low-energy electron interactions with cyclopentadienyl iron dicarbonyl manganese pentacarbonyl ((η⁵-Cp)Fe(CO)₂Mn(CO)₅), a bimetallic species with a polyhapto ligand (Cp) and seven terminal carbonyl ligands. Gas phase studies and coupled cluster calculations of observed low-energy electron-induced reactions were conducted in order to predict the performance of this precursor in FEBID. In dissociative electron attachment, we find single CO loss and cleavage of the Fe–Mn bond, leading to the formation of [Mn(CO)₅]⁻, to be the two dominant channels. Contributions through further CO loss from the intact core and the formation of [Mn(CO)₄]⁻ are minor channels. In dissociative ionization (DI), the fragmentation is significantly more extensive and the DI spectra are dominated by fragments formed through the loss of 5 and 6 CO ligands, and fragments formed through cleavage of the Fe–Mn bond accompanied by substantial CO loss. The gas phase fragmentation channels observed are discussed in relation to the underlying processes and their energetics, and in context to related surface studies and the likely performance of this precursor in FEBID.