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How do the electron-driven reactions depend on the chemical properties of the precursor molecules?

Combined experimental and theoretical insight is needed to establish quantitative criteria on how the electron-driven reactions depend on the chemical properties of precursor molecules. This approach has provided guidelines leading to design principles for novel precursors. Also, design rules for FEBID precursors derived from experimental observation have been discussed in a recent review:

Bimetallic precursors with quasi metallic band structure - unusual DEA pattern

DEA processes continuously spanning the energy range of 0 eV up to 20 eV and leading even to complete loss of the ligands has been observed for HFeCo3(CO)12. This results from the favourable effect of closely spaced occupied and unoccupied molecular energy levels, i.e., a quasi metallic band structure of the metal core within the precursor. This general behaviour has been confirmed for two other bimetallic precursors (H2FeRu3(CO)13, η5-CpFe(CO)2Mn(CO)5):

3-C3H5)Ru(CO)3Br - persistent halide ligands drive loss of other ligands

A combined experimental and theoretical has brought forward the picture that halide ligands that are persistent during the initial electron-precursor interaction stabilize the metal-centered anionic precursor fragments. This provides additional energy that drives further ligand loss. Given that the halide can be removed by post-deposition treatment, they can thus act as promoters of precursor fragmentation:

Pt(PF3)4 - non-bonding excited states drive neutral dissociation

Quantum chemical calculation on Pt(PF3)4 have revealed that neutral excitation processes lead to a multitude of non-bonding excited states indicating that neutral dissociation which has been mainly neglected so far due to experimental difficulties in fact plays a significant role in precursor fragmentation:

Cisplatin - facile formation of pure Pt

Experimental evidence indicates that the properties of FEBID precursors can in fact be tuned by suitably selected ligands leading to deposits with increased metal content. In fact, electron irradiation of cisplatin leads to pure Pt pointing to a favourable effect of NH3 and Cl ligands:

Silanes - the role of chlorine substitution on eletron-induced fragmentation mechanisms

Chlorine substitution at the silicon atom of silacyclohexane switches on DEA fragmentation channels while in the unsubstituted compound, only fragmentation via dissociative ionization (DI) has been observed:

Cr(0)(C6H6)(CO)3 - facile removal of the neutral benzene ligand

Fragments formed by loss of the neutral benzene ligand following electron attachment to Cr(0)(C6H6)(CO)3 have been observed with high intensity. This is in contrast to the anionic cyclopentadienyl ligand of complexes such as MeCpPtMe3 which produce a deposit with high carbon content due to persistence of the anionic MeCp ligand: