title: Spectroscopic and electronic structure studies of the diamagnetic side-on CuII-superoxo complex Cu(O2)[HB(3-R-5-iPrpz)3]: antiferromagnetic coupling versus covalent delocalization.
abstract: Magnetic, vibrational, and optical techniques are combined with density functional calculations to elucidate the electronic structure of the diamagnetic mononuclear side-on CuII-superoxo complex. The electronic nature of its lowest singlet/triplet states and the ground-state diamagnetism are explored. The triplet state is found to involve the interaction between the Cu xy and the superoxide pi v * orbitals, which are orthogonal to each other. The singlet ground state involves the interaction between the Cu xy and the in-plane superoxide pi v * orbitals, which have a large overlap and thus strong bonding. The ground-state singlet/triplet states are therefore fundamentally different in orbital origin and not appropriately described by an exchange model. The ground-state singlet is highly delocalized with no spin polarization.
authors.affiliation: Contribution from the Department of Chemistry, Stanford University, California 94305, USA.
authors.forename: Peng
authors.initials: P
authors.lastname: Chen
authors.forename: David E
authors.initials: DE
authors.lastname: Root
authors.forename: Cecelia
authors.initials: C
authors.lastname: Campochiaro
authors.forename: Kiyoshi
authors.initials: K
authors.lastname: Fujisawa
authors.forename: Edward I
authors.initials: EI
authors.lastname: Solomon
mesh_terms: D003300:Copper / Q000737:chemistry*; D008280:Magnetics; D008956:Models, Chemical; D008958:Models, Molecular; D009942:Organometallic Compounds / Q000737:chemistry*; D013055:Spectrophotometry, Infrared; D013481:Superoxides / Q000737:chemistry*
chemical_list: D009942:Organometallic Compounds; C472027:superoxo(hydrotris(3-adamantyl-5-isopropyl-1-pyrazolyl)borate)copper(II); D013481:Superoxides; D003300:Copper; C030973:cupric oxide