Platinum(II) complexes of mixed-valent radicals derived from cyclotricatechylene, a macrocyclic tris-dioxolene

Loughrey, J. J., Patmore, N. J., Baldansuren, A., Fielding, A. J., McInnes, E. J. L., Hardie, M., Sproules, S. and Halcrow, M. (2015) Platinum(II) complexes of mixed-valent radicals derived from cyclotricatechylene, a macrocyclic tris-dioxolene. Chemical Science, 6(12), pp. 6935-6948. (doi: 10.1039/C5SC02776D)

Abstract

Three complexes of cyclotricatechylene (H6ctc), [{PtL}3(μ3-ctc)], have been synthesised: (L = 1,2-bis(diphenylphosphino)benzene {dppb}, 1; L = 1,2-bis(diphenylphosphino)ethane {dppe}, 2; L = 4,4′-bis(tertbutyl)-2,2′-bipyridyl {tBu2bipy}, 3). The complexes show three low-potential, chemically reversible voltammetric oxidations separated by ca. 180 mV, corresponding to stepwise oxidation of the [ctc]6– catecholato rings to the semiquinonate level. The redox series [1]0/1+/2+/3+ and [3]0/1+/2+/3+ have been characterised by UV/vis/NIR spectroelectrochemistry. The mono- and di-cations have class II mixed valent character, with reduced radical delocalisation compared to an analogous bis-dioxolene system. The SOMO composition of [1•]+ and [3•]+ has been delineated by cw EPR, ENDOR and HYSCORE spectroscopies, with the aid of two monometallic model compounds [PtL(DBsq•)]+ (DBsqH = 3,5-bis(tertbutyl)-1,2-benzosemiquinone; L = dppe or tBu2bipy). DF and time-dependent DF calculations confirm these interpretations, and demonstrate changes to spin- delocalisation in the ctc macrocycle as it is sequentially oxidised.

• Item Type: Articles
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Sproules, Dr Stephen
• Authors: Loughrey, J. J., Patmore, N. J., Baldansuren, A., Fielding, A. J., McInnes, E. J. L., Hardie, M., Sproules, S., and Halcrow, M.
• College/School: College of Science and Engineering > School of Chemistry
• Journal Name: Chemical Science
• Publisher: Royal Society of Chemistry
• ISSN: 2041-6520
• Published Online: 20 August 2015
• Copyright Holders: Copyright © 2015 The Royal Society of Chemistry
• First Published: First published in Chemical Science 6(12):6935-6948
• Publisher Policy: Reproduced under a Creative Commons License