New structural aspects of alpha-pyrrolidinonate- and alpha-pyridonate-bridged, homo- and mixed-valence, di- and tetranuclear cis-diammineplatinum complexes: Eight new crystal structures, stoichiometric 1:1 mixture of pt(2.25+)4 and Pt(2.5+)4, new quasi-one-dimensional halide-bridged [pt(2.5+)4-Cl...]∞ system, and consideration of solution properties

Ken Sakai, Yuko Tanaka, Yuriko Tsuchiya, Kentaro Hirata, Taro Tsubomura, Seiichiro Iijima, Ashis Bhattacharjee

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Abstract

Eight new crystalline α-pyrrolidinonate-bridged homo- and mixed- valence cis-diammineplatinum dimers and tetramers, HT-[Pt(2.0+)2(NH3)4(μ- C4H6NO)2](ClO4)2 (2), HH-[Pt(2.25+)2(NH3)4(μ-C4H6NO)2]2- (ClO4)5 (4), HH-[Pt(2.25+)2(NH3)4(μ-C4H6NO)2]2(PF6)3(NO3)2 (5), {HH-[Pt(2.25+)2(NH3)4(μ-C4H6NO)2]2}-{HH-[Pt(2.5+)2 (NH3)4(♂- C4H6NO)2(NO3)]2}(PF6)2(NO3)7 · 6H2O (7), HH- [Pt(2.5+)4(NH3)8(μ-C4H6NO)4(Cl)]-(ClO4)3Cl2(9),HH- [Pt(3.0+)2(NH3)4(μ-C4H6NO)2(Cl)2](NO3)2 (11), HH- [Pt(3.0+)2(NH3)4(μ-C4H6NO)2(Cl)(NO3)](NO3)2 · H2O (12), and HT- [(H2O)(H3N)2Pt(3.0+)(μ-C4H6NO)2Pt(3.0+)(NH3)(μ-OH)]2 (NO3)6 · 4H2O (14), have been isolated and characterized by X-ray diffraction, where HH and HT correspond to the head-to-head and head-to-tail isomers, respectively. The first spontaneous resolution has been observed for the chiral HT-Pt(2.0+)2 molecules (2). 7 has turned out to be the first 1:1 'stoichiometric' mixture of blue and tan (Pt(2.25+)4 and Pt(2.5+)4). The structural evidence supporting the axial coordination behaviors of the Pt(2.5+)4 tetramer has been obtained (7 and 9). A very unique quasi-one- dimensional halide-bridged system having a chain definition of [Pt(2.5+)4- Cl···]∞ has been characterized (9). The HT-Pt(3.0+)2 dimer has been found to release an NH3 group in aqueous media to form a dimer of dimers linked by μ-OH bridges (14). Relationships between the structural parameters and the average Pt oxidation state have been examined in detail to better understand the structure-transformation properties of the platinum-blue family. Remarkable structural differences observed between the pentacyclic α-pyrrolidinonate and the hexacyclic α-pyridonate systems are rationally interpreted in terms of differences in both the N-C-O bite angle and the Pt- N-C angle around the bridging geometry. In addition, spectrophotometric studies reveal that an outer-sphere electron-transfer process between two Pt- (2.25+)4 molecules takes place to afford a Pt(2.0+)4 and a Pt(2.5+)4 molecule. General consideration for the solution properties of this family is also described. The synthesis of an α-pyridonate Pt(2.5+)4 complex is also reported.

Original languageEnglish
Pages (from-to)8366-8379
Number of pages14
JournalJournal of the American Chemical Society
Volume120
Issue number33
DOIs
Publication statusPublished - Aug 26 1998
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Catalysis
  • Chemistry(all)
  • Biochemistry
  • Colloid and Surface Chemistry

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