title: Deep blue mixed-valent PtIIIPtIIIPtII complex [Pt3Br2(mu-pz)6] (pz=pyrazolate) showing valence-detrapping behavior in solution.
abstract: The oxidation of the pyrazolate bridged cyclic PtII trimer, [Pt3(mu-pz)6] (1), in the presence of bromide ion gave a deep blue mixed-valent Pt(II,III,III) complex, [Pt3Br2(mu-pz)6] (2). The structural analysis of 2 disclosed that the complex has localized Pt--Pt bond. Our theoretical calculations revealed that the HOMO and LUMO of Pt3 (II,III,III) species mainly consists of (dsigma-dsigma) and (dsigma-dsigma)* orbitals, respectively, and the origin of deep blue color of the bromo complex, 2, arises from the (dsigma-dsigma)-->(dsigma-dsigma)* transition. Unique fluxional behavior was observed due to valence-detrapping of 2 in solution. The activation parameters of the valence-detrapping of 2 obtained by Eyring analyses were DeltaH(not equal)=37(2) kJ mol(-1) and DeltaS(not equal)=-67(7) J mol(-1) K(-1).
authors.affiliation: Department of Applied Chemistry, Faculty of Engineering, Nagasaki University, Bunkyo-machi, Nagasaki 852-8521, Japan. kumks@nagasaki-u.ac.jp
authors.forename: Keisuke
authors.initials: K
authors.lastname: Umakoshi
authors.forename: Takashi
authors.initials: T
authors.lastname: Kojima
authors.forename: Yong Hun
authors.initials: YH
authors.lastname: Kim
authors.forename: Masayoshi
authors.initials: M
authors.lastname: Onishi
authors.forename: Yoshihide
authors.initials: Y
authors.lastname: Nakao
authors.forename: Shigeyoshi
authors.initials: S
authors.lastname: Sakaki