1. Contribution from The School of Chemistry, The University of Birmingham, Edgbaston, Birmingham B15 2TT, UK, Istituto FRAE-CNR, via Gobetti 101, 40129, Bologna, Italy, Dipartimento di Chimica “G. Ciamician” dell'Università di Bologna, via Selmi 2, 40126, Bologna, Italy, and The Department of Chemistry, Imperial College, South Kensington, London SW7 2AY, UK