The cross-coupling reaction Ar−X + Nu- → Ar−Nu + X-, catalyzed by Pd(0) complexes, was studied theoretically by means of DFT calculations; Ph−Cl was used as a substrate and HS- as the nucleophile. The studied catalysts are the pristine Pd(0) complexes Pd0(PR3)2 (1R; R = H, vinyl, Ph), the corresponding anionic complexes Pd0(PR3)2Cl- (1R,Cl), proposed by two of us (C.A. and A.J.), and the chelated complexes with diphosphine ligands PH2(CH2)nPH2 (2H,n; n = 2−6). The full catalytic cycles were studied for 1H, 1H,Cl, 2H,3,and 2H,6. The efficiency of a catalytic cycle under turnover conditions is determined by the energetic span, the energy difference between the summit and trough of the cycle; the smaller the energy span, the higher the turnover frequency of the cycle. In this sense, the best Pd(0) catalyst was found to be the anionic 1H,Cl species. The DFT analysis shows that the anionic catalyst so formed is superior to the pristine species, since it “flattens” the energy landscape of the catalytic cycle by...