Synthesis, Structure, and 195Pt NMR Solution Studies of a Reactive Binuclear Platinum(III) Complex: [Pt2(en)2(C5H4NO)2(NO2)(NO3)](NO3)2.0.5H2O

Thomas V. O'Halloran, Michael M. Roberts, Stephen J. Lippard

Research output: Contribution to journalArticle

72 Scopus citations

Abstract

Oxidation of the a-pyridonate- (C5H4NO-) bridged diplatinum(II) complex [Pt2(en)2(C5H4NO)2]2+(2), where en = ethylenediamine, in nitric acid leads to the formation of a metal-metal-bonded diplatinum(III) complex, [Pt2(en)2(C5H4NO)2(NO2)-(NO3)]2+(1). In the structure of 1, two (ethylenediamine)diplatinum(III) units are linked by a metal-metal single bond and two a-pyridonate ligands bridging in a head-to-head fashion. The 2.6382 (6) A Pt-Pt bond axis is capped by nitrite, Pt-N = 2.109 (1) A, and nitrate, Pt-O =2.307 (9) A, ligands. These Pt-axial ligand distances nicely illustrate a structural trans influence mediated by the metal-metal bond. The coordinated nitrite group is disordered over two positions about the Pt-N axis and is bonded to the platinum atom having two N- and two O-donor ligands. As shown by 195Pt NMR spectroscopy, 1 has a binuclear, metal-metal-bonded structure in freshly prepared aqueous or dimethylformamide (DMF) solutions. In DMF the platinum resonances occur at +541 (PtN302) and -1141 (PtN40) ppm from [PtCl6]2-, with J(195Pt-l95Pt) = 6850 Hz. Decomposition of 1 to form 2 occurs slowly in solution, as revealed by 195Pt NMR spectroscopy. Reductive elimination of nitrite (N02-) to form the nitronium (N02+) ion is postulated to explain this decomposition, since nitrobenzene or p-nitrophenol is generated in aqueous solutions of 1 containing tetraphenylborate or phenol, respectively. The nitrate salt of compound 1, crystallizes in the monoclinic space group with a = 17.934 (1) A, b = 11.491 (1) A, c = 13.507 (1) A, ß= 108.84 (1)°, V = 2634 A3, Z = 4, pcalcd= 2.369 g cm-3, and pobsd = 2.379 (5) g cm-3. The structure was refined to R = 0.035 using 2686 diffractometer.

Original languageEnglish (US)
Pages (from-to)957-964
Number of pages8
JournalInorganic chemistry
Volume25
Issue number7
DOIs
StatePublished - Jan 1 1986

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Inorganic Chemistry

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