title: Syntheses and physical properties of quasi-one-dimensional halogen-bridged Cu(II)(-)Pt(IV) mixed-metal complexes [Cu(chxn)(2)][PtX(2)(chxn)(2)]X(4).
abstract: Quasi-one-dimensional halogen-bridged Cu(II)-Pt(IV) mixed-metal complexes of the form [Cu(chxn)(2)][PtX(2)(chxn)(2)]X(4), where chxn = 1R,2R-diaminocyclohexane and X is either Cl or Br, have been synthesized. The crystal structures of these compounds have been determined by single-crystal X-ray diffraction. The Cl-bridged compound crystallizes in the space group I222 with dimensions a = 24.237(1) A, b = 5.103(1) A, c = 6.854(1) A, and V = 847.7(1) A(3) and with Z = 1. The Br-bridged complex crystallizes in the space group I222 with dimensions a = 23.700(8) A, b = 5.344(5) A, c = 6.978(8) A, and V = 883.8(8) A(3) and with Z = 1. These structures are isomorphic to each other and to homometal [Pt(chxn)(2)][PtX(2)(chxn)(2)]X(4) complexes. In these complexes, the planar [Cu(chxn)(2)] and the octahedral [PtX(2)(chxn)(2)] groups are stacked alternatively with the axial bridging halogen ions, forming linear chain structures. The neighboring [Cu(chxn)(2)] and [PtX(2)(chxn)(2)] moieties along the chains are linked by hydrogen bonds between amino hydrogens and the counteranions (X). Moreover, there are hydrogen bonds among the neighboring chains that form a two-dimensional hydrogen-bonded network parallel to the bc plane. Therefore, the Cu(II) and Pt(IV) units are two-dimensionally ordered. The b axes correspond to the Cu(II)-Pt(IV) separations, which are shorter than those of [Pt(chxn)(2)][PtX(2)(chxn)(2)]X(4) due to the smaller ionic radius of the Cu(II) ions. In the XP spectra, the Pt(IV) 4f(7/2) and Pt(IV) 4f(5/2) binding energies in homometal [Pt(chxn)(2)][PtX(2)(chxn)(2)]X(4) are lower than those of [Cu(chxn)(2)][PtX(2)(chxn)(2)]X(4) (X = Cl and Br), indicating that the electron-phonon interaction in Cu(II)-Pt(IV) compounds is stronger than that in Pt(II)-Pt(IV) compounds. In the Raman spectra, nu(Pt(IV)(-)X) of the homometal Pt(II)-Pt(IV) complexes is lower than that of the Cu(II)-Pt(IV) complexes, indicating again that the electron-phonon interaction in Cu(II)-Pt(IV) compounds is stronger than that of Pt(II)-Pt(IV) compounds. The temperature-dependent magnetic susceptibilities of the Cu(II)-Pt(IV) complexes show weak antiferromagnetic interactions between Cu(II) components along the chain axes.
authors.affiliation: Graduate School of Human Informatics, Nagoya University, Chikusa-ku, Nagoya 464-8601, Japan.
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authors.lastname: Toriumi