[1] Univ Zaragoza, Dept Quim Inorgan, Inst Ciencia Mat Aragon, CSIC, E-50009 Zaragoza, Spain
[2] Univ Barcelona, Dept Quim Inorgan, E-08028 Barcelona, Spain
[3] Univ Barcelona, Inst Quim Teor & Computac IQTCUB, E-08028 Barcelona, Spain
[4] CSIC, Inst Quim Fis Rocasolano, E-28006 Madrid, Spain