In this paper, we investigate the transport and thermoelectric properties of a four-atom nanostructure in different configurations. As an impurity, one of its atoms is assumed to be different from the others. These calculations are performed using the Green's function technique within the tight-binding approach. In the hopping of electrons between atoms of the molecule, the electron wave functions undergo constructive and destructive interferences so that in some configurations and at certain energies, the local density of states finds drastic variation. Correspondingly, in the vicinity of these energies, a Fano resonance is observed in the electronic transmission coefficient curve. The variation in the electronic density of states and the existence of Fano resonance, in turn, lead to a nanozero Seebeck coefficient in the system. In unbranched or impure molecules, despite having a cyclic geometric structure, this phenomenon is not observed. In these molecules, when the number of branches connected to the molecule that has a cyclic structure is larger, the Seebeck coefficient has a higher value. Finally, we calculate and discuss the power and merit coefficients that are important from an experimental viewpoint for different possible molecule configurations. This research facilitates the preparation of compounds with a large Seebeck coefficient, which can lead to the preparation of thermoelectric converter devices with a high thermoelectric figure of merit.