The thiol group attaches strongly to gold surfaces and can thus be used as interconnects of molecular wires in nano electronics. A phenyl molecule attached to gold via a thiol group has been investigated by ab initio Hartree-Fock calculations in order to understand electronic transport through the sulfur-gold bridge. In our analysis of the coupling between gold and the molecule, we found that the electronic system of the gold substrate interacts directly with the conducting states of the molecule and thus forms an ohmic contact to the molecular wire.