| Abstract
| - The objective of the present study is to identify possible adsorption configurations of pyrrole on Mo(110)using density functional theory (DFT) calculations. Several adsorption configurations were studied includingpyrrole and pyrrolyl adsorption as parallel, perpendicular, and tilted adsorption modes relative to the Mo(110) surface plane. Based on the DFT calculations, pyrrole is suggested to adsorb in a parallel mode withrespect to the Mo(110) surface through its π-orbital as μ3,η5-Pyr-0° with an adsorption energy of −28.7 to−31.5 kcal mol-1. The possibility of a coexisting mode where pyrrole adsorbs on the surface with a slightlytilted molecular plane as μ3,η4(N,C2,C3,C4)-Pyr-5° is also likely to occur, particularly at higher pyrrolecoverages. The slightly tilted configuration is suggested to arise from the lateral interactions of adsorbedpyrrole on Mo(110), and not the result of a phase transformation on the surface since this requires a relativelyhigh activation energy as indicated by additional linear synchronous transit (LST)/quadratic synchronoustransit (QST) calculations. Both adsorption geometries bond to three surface Mo atoms, and Mo(110) did notpromote hydrogen abstraction. Pyrrolyl adsorption on Mo(110) is energetically possible, but unlikely to occurbecause gas-phase hydrogen has not been previously experimentally observed as a pyrrole decompositionproduct on Mo(110).
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