Using alkanethiol dense packing as a starting point, we have found six prototypical packing structures commensurate with the (3 x 2 root 3) supercell of the Au (111) surface. Five of the six structures are not compatible with the flat surface conditions but can be Fitted to a reconstructed surface. Combined with density functional theory calculations and simulations of grazing incidence X-ray diffraction maps and of scanning tunneling microscopy images, this allowed us to refine and assess the recently proposed models of the c(4 x 2) self-assembled monolayers involving thiolate-adatom and thiolate-adatom-thiolate species and to propose a new model with four gold adatoms per unit cell.