Copper(II)-platinum(IV) linear-chain complexes of the type [CuxPt 1-x(en)2][Pt(en)2Cl2][ClO4] 4 (en = 1,2-diaminoethane) have been synthesised where 0.58 < x < 1. The intensely red, highly dichroic needles obtained when x = 0.58 become much paler and lose their dichroism as x → 1. The intense z-polarised band at 18 000-23 000 cm-1 (single-crystal transmission) for x < 1 is believed to be due to the PtII → PtIV intervalence transition of PtII-PtIV domains whose symmetric stretching mode ν1,νsym(Cl-PtIV-Cl) occurs at 313 cm-1. For the stoichiometric CuII-PtIV chain complex, the CuII → PtIV transition probably lies in the ultraviolet region and the ν′1,νsym(Cl-PtIV-Cl) stretching mode occurs at 341 cm-1. This band displays no resonance enhancement with any excitation lines in the visible or near-ultraviolet region; both this fact, as well as the high value for ν1′, imply that the stoichiometric material is highly valence localised, as expected for a system consisting of chains in which the unpaired electrons are in dx2 - y2 orbitals (i.e., ⊥ chain direction) on metal ions which are 10.8 Å apart.
|Number of pages||4|
|Journal||Journal of the Chemical Society, Dalton Transactions|
|Publication status||Published - 1991 Dec 1|
ASJC Scopus subject areas