New compounds of the general formulas [M(Ar-BIAN)(2)]BF4 and [M(Ar-BIAN)(NCMe)(2)]BF4, where M=Cu-1 or Ag-1 and Ar-BIAN = bis(aryl)acenaphthenequinonediimine, were synthesized by the direct reaction of [Cu(NCMe)(4)]BF4 or [Ag(NCMe)(4)]BF4 with the corresponding Ar-BIAN ligand in dried CH2Cl2. The synthesized compounds are [M(o, d, p-Me3C6H2-BIAN)(2)]BF4 where M = Cu-1 (1) and Ag-1 (2), [M(o,d-iPr(2)C(6)H(3)-BIAN)(NCMe)(2)]BF4 where M = Cu-1 (3) and Ag-1 (4), and [Ag(o,d-iPr(2)C(6)H(3)-BIAN)(2)]BF4 (5). The crystal structures of compounds 1-3 and 5 were solved by singlecrystal X-ray diffraction. In all cases copper(I) or silver(I) are in a distorted tetrahedron that is constructed from the four nitrogen atoms of the two a-diimine ligands or, in 3, from one a-diimine ligand and two acetonitrile molecules. All compounds were characterized by elemental analyses, matrix-assisted laser desorption ionization time-of-flight mass spectrometry, and IR, UV-vis, and H-1 NMR spectroscopy. The analysis of the molecular geometry and the energetic changes for the formation reactions of the complexes, in a CH2Cl2 solution, were evaluated by density functional theory calculations and compared with the experimental results.