Coinage and alkali metal mixed clusters, M4Na- (M = Cu, An) have been investigated experimentally using photoelectron spectroscopy and computationally at correlated ab initio levels. The related Cu4Li-, Ag4Li-, Ag4Na-, and Au4Li- clusters as well as the neutral Cu4Li2 and Cu4Na2 clusters have also been studied computationally. The calculations show that the two lowest isomers of the negatively charged clusters include a pyramidal C-4v structure and a planar C-2v species. For Cu4Li- and Cu4Na-, the C-4v structure is calculated at correlated ab initio level to be 30.9 and 16.9 kJ/mol below the planar C-2v, isomer, whereas the planar isomers of Au4Li- and Ai(4)Na(-) are found to be 29.7 and 49.4 U/mol below the pyramidal ones. For Ag4Li- and Ag4Na-, the pyramidal isomers are the lowest ones. Comparison of the calculated and measured photoelectron spectra Of Cu4Na- and Au4Na-shows that the pyramidal Cu4Na- cluster of C-4v symmetry and the planar Au4Na- of C-2v symmetry are detected experimentally. Calculations of the magnetically induced current density in Cu4Li- and Cu4Li2 using the Gauge-Including Magnetically Induced Current (GIMIC) method show that strong, ring currents are sustained mainly by the highest-occupied molecular orbital primarily derived from the Cu 4s. The GIMIC calculations thus show that the Cu-4(2-) ring is sigma-aromatic and that the d orbitals do not play any significant role for the electron delocalization effects. The present study does not support the notion that the square-planar Cu-4(2-) is the first example of d-orbital aromatic molecules.