* Corresponding authors

^a Centro Grandi Strumenti, University of Pavia, Via Bassi 21, Pavia, Italy
E-mail: massimo.boiocchi@elicona.unipv.it
Fax: +39 0382 422251
Tel: +39 0382 987531

^b Department of General Chemistry, University of Pavia, Viale Taramelli 12, Pavia, Italy
E-mail: angelo.taglietti@unipv.it
Fax: +39 0382 528544
Tel: +39 0382 987239

^c Department of Organic Chemistry, University of Pavia, Viale Taramelli 10, Pavia, Italy
E-mail: dario.pasini@unipv.it
Fax: +39 0382 987323
Tel: +39 0382 987835