  Graphdiyne-based carbon systems generate intriguing layered sp-sp$^2$
organometallic lattices, characterized by flexible acetylenic groups connecting
planar carbon units through metal centers. At their thinnest limit, they can
result in two-dimensional (2D) organometallic networks exhibiting unique
quantum properties and even confining the surface states of the substrate,
which is of great importance for fundamental studies. In this work, we present
the on-surface synthesis of a highly crystalline 2D organometallic network
grown on Ag(111). The electronic structure of this mixed honeycomb-kagome
arrangement - investigated by angle-resolved photoemission spectroscopy and
scanning tunneling spectroscopy - reveals a strong electronic conjugation
within the network, leading to the formation of two intense electronic
band-manifolds. In comparison to theoretical density functional theory
calculations, we observe that these bands exhibit a well-defined orbital
character that can be associated with distinct regions of the sp-sp$^2$
monomers. Moreover, we find that the halogen by-products resulting from the
network formation locally affect the pore-confined states, causing a
significant energy shift. This work contributes to the understanding of the
growth and electronic structure of graphdiyne-like 2D networks, providing
insights into the development of novel carbon materials beyond graphene with
tailored properties.
