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.
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.
Chen
Peng
P
Contribution from the Department of Chemistry, Stanford University, California 94305, USA.
Root
David E
DE
Campochiaro
Cecelia
C
Fujisawa
Kiyoshi
K
Solomon
Edward I
EI
D003300:Copper / Q000737:chemistry*; D008280:Magnetics; D008956:Models, Chemical; D008958:Models, Molecular; D009942:Organometallic Compounds / Q000737:chemistry*; D013055:Spectrophotometry, Infrared; D013481:Superoxides / Q000737:chemistry*
D009942:Organometallic Compounds; C472027:superoxo(hydrotris(3-adamantyl-5-isopropyl-1-pyrazolyl)borate)copper(II); D013481:Superoxides; D003300:Copper; C030973:cupric oxide