1. Department of Chemistry and Center for Theoretical Studies, Indian Institute of Technology, Kharagpur 721302, India
2. This is a Chemical Reviews Perennial Review. The root paper of this title was published in Chem. Rev. 2006, 106, 2065−2091, DOI: 10.1021/cr040109f; Published (Web) May 25, 2006. Update 1 of this title was published in Chem. Rev. 2007, 107, PR46−PR74, DOI: 10.1021/cr078014b; Published (Web) September 12, 2007. Updates to the text appear in red type.