Selection of cross-coupling reaction products from Pd-cyclometalled complexes deposited on Ag(110) by tuning preparation conditions

Pd-cyclometallated compounds may be relevant for catalytic purposes, but very little is known about their interactions with metal substrates. Here we report a combined low-temperature scanning tunnelling microscopy and density functional theory investigation on the interaction of the cyclometallated compound C22H14Br2N2Pd2Cl2 on Ag(110). Upon deposition at low temperature the molecules adsorb in a disordered manner on the surface but, upon annealing to room temperature, a cross-coupling reaction between molecular fragments occurs and ordered ad-layers are observed. Comparison of the present result with those previously reported for deposition at 300 K and annealing to higher temperature shows that the final product of the cross-coupling reaction is a different di-phenyl-bi-pyridine isomer. Therefore, we confirm the presence of a rich chemistry at the base of the cyclometallate-metal interaction, that significantly modifies the nature of the compounds, and we envisage the possibility to tune the final product of cross-coupling reactions by selecting the suitable preparation protocol.