Structure of the mixed-valence platinum complexes [PtII(en)(SCN)2][PtIV(en)(SCN)2I2] and cis-[PtII(NH3)2(SCN)2][PtIV(NH3)2(SCN)2I2] studied by the method of radial distribution functions of atoms
作者:V.I. Korsunsky、G.S. Muraveiskaya、A.A. Sidorov
DOI:10.1016/s0020-1693(00)82973-4
日期:1991.9
Using the method of radial distribution functions of atoms obtained by Fourier transform of powder X-ray patterns it has been shown directly that the structures of the mixed-valence complexes cis-[Pt(II)(NH3)2(SCN)2][Pt(IV)(NH3)2(SCN)2I2] (I) and [Pt(II)(en)(SCN)2][Pt(IV)(en)(SCN)2I2] (II) (en = ethylenediamine) contain the linear chains ...I-Pt(IV)-I...Pt(II)...I-Pt(IV)-I...I-, wherein square-planar complexes of Pt(II) alternate with octahedral complexes of Pt(IV). Such a structure for I had earlier been proposed only on the basis of indirect spectroscopical data. The distances Pt(IV)-I and Pt(II)...I have been determined. The first one is 2.70 angstrom in both the complexes and the second is 3.50 angstrom in I and 3.23 angstrom in II. The distances Pt(II)...I are considerably longer than corresponding distances in the similar mixed-valence complex of known structure [Pt(II)(en)2][Pt(IV)(en)2I2](ClO4)4 (IV) (about 3.10 angstrom). The elongation of the Pt(II)...I contact corresponds to the smaller bridge role of I atoms in the thiocianate complexes, to the smaller electron delocalization over the chain of Pt and I atoms and, hence, to a more pronounced division of the system into true complexes of Pt(II) and Pt(IV) than in IV.