Inorganic Chemistry, Vol.42, No.19, 5801-5801, 2003
Triangular, ferromagnetically-coupled Cu-3(II)-pyrazolato complexes as possible models of particulate methane monooxygenase (pMMO)
Magnetic susceptibility and EPR studies show that trinuclear Cu-II-pyrazolato complexes with a Cu-3(mu(3)-X)(2) core (X = Cl, Br) are ferromagnetically coupled: J(Cu-Cu) = +28.6 cm(-1) (X = Cl), +3.1 cm(-1) (X = Br). The orderly transition from an antiferromagnetic to a ferromagnetic exchange among the Cu centers of Cu-3(mu(3)-X) complexes, X = O, OH, Cl, Br, follows the change of the Cu-X-Cu angle from 120degrees to similar to80degrees. The crystal structures of [BU4N](2)[Cu-3(mu(3)-Br)(2)(mu-pz*)(3)Br-3] (pz* = pz (1a) or 4-O2N-pz (1b), pz = pyrazolato anion, C3H3N21-) are presented.