The valence photoabsorption spectra of the series of the monoanionic closed shell icosahedral clusters MAu12- with M = V, Nb and Ta have been calculated with the time-dependent density functional theory (TDDFT), employing the zero-order regular approximation (ZORA) at both scalar relativistic and spin orbit coupling levels. The calculated photoabsorption spectra show interesting variations according to the nature of the encapsulated metal atom. Spin-orbit coupling plays an important role in these systems. The comparison with the neutral isoelectronic clusters WAu12 and MoAu12 suggests a curious relationship along the diagonal of the periodic table. (C) 2008 Elsevier B.V. All rights reserved.