Adsorption structure, thermal reaction and initial pathways of 1,2-benzyne on Cu(100)

1,2-C6H4I2 is used as precursor to generate 1,2-C6H4 (ortho-C6H4) on Cu(100). The reflection–absorption infrared spectroscopy (RAIRS) confirms the vertical adsorption geometry of 1,2-C6H4 on Cu(100), which agrees with that predicted theoretically. H2 evolving between 620K and 870K is the only reaction product detected from the 1,2-C6H4 decomposition in temperature-programmed reaction/desorption (TPR/D). Our calculations indicate that the 1,2-C6H4 primarily undergoes C3–H bond scission, forming 1,2,3-C6H3, with distorted C6 ring, and H atom on the surface without ring rupture (C1–C2 bond dissociation) prior to H loss. Furthermore, isomerization of the 1,2-C6H4, if it does occur, may proceed via dehydrogenation–hydrogenation, instead of H-shift.