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Reversible C–C bond formation at a triply cyclometallated platinum(iv) centre
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Shaw, Paul Anthony, Clarkson, Guy J. and Rourke, Jonathan (2017) Reversible C–C bond formation at a triply cyclometallated platinum(iv) centre. Chemical Science . doi:10.1039/C7SC01361B ISSN 2041-6520.
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Official URL: http://dx.doi.org/10.1039/C7SC01361B
Abstract
The oxidation of the tribenzylphosphine derivative of the doubly cylcometallated platinum(II) complex of diphenylpyridine, 1, with PhICl2 led, as a first step, to the formation of a highly electrophilic metal centre which attacked the benzyl phosphine to give a triply cyclometallated species as the arenium ion. The highly acidic arenium ion protonated unreacted starting 1, a reaction that could be supressed by the addition of water, and gave the neutral species 2(t). Octahedral complex 2(t) was induced to reductively couple, with two five-membered rings coupling to give square planar complex 5 containing a nine-membered ring. The crystal structure of 5 showed the nine-membered ring to span trans across the square planar metal accompanied by considerable distortion: the P–Pt–N bond angle is 155.48(5)°. Oxidation of 5 with PhICl2 resulted in the addition of two chlorides and a change of the nine-membered ring ligand coordination to cis at an octahedral centre, still with considerable distortions: the P–Pt–N bond angle in the crystal structure of 6 is 99.46(5)°. Treatment of 2(t) with AgBF4 also induced a coupling to give a nine-membered ring, and the fluxional three coordinate complex 7. A mono-methylated version of 1, Me-1, was prepared and similar reactions were observed. The presence of the methyl group allowed us to observe selectivity in the coupling reaction to give the nine-membered ring, with two products (a-Me-7 and b-Me7) being initially formed in the ratio 7 : 1. The concentrations of two products changed with time giving a final ratio of 1 : 8 at room temperature (half-life 48 hours), the equilibration being made possible by a reversible C–C bond forming reaction. Reaction of complexes 7 with CO or hydrogen left the nine-membered ring intact, though oxidative degradation resulted in decomplexation of the phosphine donor, accompanied by formation of a P[double bond, length as m-dash]O group.
Item Type: | Journal Article | ||||||
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Subjects: | Q Science > QD Chemistry | ||||||
Divisions: | Faculty of Science, Engineering and Medicine > Science > Chemistry | ||||||
Library of Congress Subject Headings (LCSH): | Transition metals, Transition metal catalysts, Metal carbonyls | ||||||
Journal or Publication Title: | Chemical Science | ||||||
Publisher: | Royal Society of Chemistry | ||||||
ISSN: | 2041-6520 | ||||||
Official Date: | 5 June 2017 | ||||||
Dates: |
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DOI: | 10.1039/C7SC01361B | ||||||
Status: | Peer Reviewed | ||||||
Publication Status: | Published | ||||||
Access rights to Published version: | Restricted or Subscription Access | ||||||
Date of first compliant deposit: | 12 June 2017 | ||||||
Date of first compliant Open Access: | 13 June 2017 | ||||||
Funder: | Engineering and Physical Sciences Research Council (EPSRC), Advantage West Midlands (AWM), European Regional Development Fund (ERDF) |
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