Quasi-one-dimensional halogen-bridged CuII-PtIV mixed-metal complexes of the form [Cu(chxn)2] [PtX2(chxn)2]X4, 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) Å, b = 5.103(1) Å, c = 6.854(1) Å, and V = 847.7(1) Å3 and with Z = 1. The Br-bridged complex crystallizes in the space group I222 with dimensions a = 23.700(8) Å, b = 5.344(5) Å, c = 6.978(8) Å, and V = 883.8(8) Å3 and with Z = 1. These structures are isomorphic to each other and to homometal [Pt(chxn)2][PtX2(chxn)2]X4 complexes. In these complexes, the planar [Cu(chxn)2] and the octahedral [PtX2(chxn)2] groups are stacked alternatively with the axial bridging halogen ions, forming linear chain structures. The neighboring [Cu(chxn)2] and [PtX2(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 CuII and PtIV units are two-dimensionally ordered. The b axes correspond to the CuII-PtIV separations, which are shorter than those of [Pt(chxn)2][PtX2(chxn)2]X4 due to the smaller ionic radius of the CuII ions. In the XP spectra, the PtIV 4f7/2 and PtIV 4f5/2 binding energies in homometal [Pt(chxn)2][PtX2(chxn)2]X4 are lower than those of [Cu(chxn)2][PtX2(chxn)2]X4 (X = Cl and Br), indicating that the electron-phonon interaction in CuIIPtIV compounds is stronger than that in PtII-PtIV compounds. In the Raman spectra, v(PtIV-X) of the homometal PtII-PtIV complexes is lower than that of the CuII-PtIV complexes, indicating again that the electron-phonon interaction in CuII-PtIV compounds is stronger than that of PtII-PtIV compounds. The temperature-dependent magnetic susceptibilities of the CuII-PtIV complexes show weak antiferromagnetic interactions between CuII components along the chain axes.
ASJC Scopus subject areas
- Physical and Theoretical Chemistry
- Inorganic Chemistry