Dimerization processes of square planar [PtII( tbpy)(dithiolato)]+ radicals

József Sándor Pap, Flávio Luiz Benedito, Eberhard Bothe, Eckhard Bill, Serena De Beer George, Thomas Weyhermüller, Karl Wieghardt

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Abstract

The preparation and structural characterization of the neutral, square planar complexes [PtII(tbpy)(A)] (1), [Pt II(tbpy)(B)] (2), and [PtII(PPh 3)2(B)] (3) have been accomplished, where ( tbpy) = 4,4′-di-tert-butylpyridine, (A)2- = 3,6-bis(trimethylsilyl)-1,2-benzenedithiolate(2-), and (B)2- = 1,2-bis(4-tert-butylphenyl)ethylene-1,2-dithiolate(2-) and (A )1- and (B)1- represent the corresponding monoanionic radicals. Electrochemical and chemical one-electron oxidation of 1 and 2 in CH2Cl2 solution affords the monomeric monocations [PtII(tbpy)(A )]+ (1a) and [PtII(tbpy) (B)]+ (2a), both of which possess an S = 1/2 ground state. The corresponding spin doublet monocationic dimers [PtII 2(tbpy)2(A)(A)]+ (1b) and [PtII2(tbpy)2(B)(B )]+ (2b) were electrochemically generated in solution (50% oxidation) and identified by X-band EPR spectroscopy. Complete one-electron oxidation of 1 and 2 yielded the diamagnetic dimers [Pt II2(tbpy)2(A) 2]2+ (1c) and [PtII2( tbpy)2(B)2]2+ (2c) which are in equilibrium with the corresponding paramagnetic monomers 1a and 2a in solution. The crystal structure of [PtII2( tbpy)2(B)2](PF 6)2·3CH2Cl2 (2c) revealed a centrosymmetric, lateral dimer whose bridging part is a PtII 22-S)2 rhomb; the metal ions possess a square based pyramidal geometry. Solid-state sulfur K-edge X-ray absorption spectra of 1, 2, 2a, 2c, and [PtII(B) 2]0 (4) have been recorded, which clearly show that a sulfur-centered radical (B)1- is present in 2a, 2c, and 4. The absence of ligand-based radicals in 1 and 2 is also clearly established. One-electron oxidation of [Pt(PPh3)2(B)] (3) afforded only the spin doublet species [PtII(PPh3) 2(B)]+ (3a); no dimer formation was detected. Synthesis and crystal structure of square planar [Pt II(B)2]0·thf are also reported.

Original languageEnglish
Pages (from-to)4187-4196
Number of pages10
JournalInorganic Chemistry
Volume46
Issue number10
DOIs
Publication statusPublished - May 14 2007

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Inorganic Chemistry

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    Pap, J. S., Benedito, F. L., Bothe, E., Bill, E., George, S. D. B., Weyhermüller, T., & Wieghardt, K. (2007). Dimerization processes of square planar [PtII( tbpy)(dithiolato)]+ radicals. Inorganic Chemistry, 46(10), 4187-4196. https://doi.org/10.1021/ic070130+