Unusual Photooxidation of S-Bonded Mercaptopyridine in a Mixed Ligand Ruthenium(II) Complex with Terpyridine and Bipyridine Ligands

Autor(es)

da Silva, Maria Rosana E. ^{[1, 2]} ; Auvray, Thomas ^[2] ; Laramee-Milette, Baptiste ^[2] ; Franco, Mauricio P. ^[1] ; Braga, Ataualpa A. C. ^[1] ; Toma, Henrique E. ^[1] ; Hanan, Garry S. ^[2]

Afiliação do(s) autor(es)

^[1] Univ Sao Paulo, Inst Chem, Av Prof Lineu Prestes 748, BR-05508000 Sao Paulo, SP - Brazil

^[2] Univ Montreal, Dept Chim, Montreal, PQ H3T 1J4 - Canada

• Tipo de documento: Artigo Científico
• Fonte: Inorganic Chemistry; v. 57, n. 9, p. 4898-4905, MAY 7 2018.
• Citações Web of Science: 4

Resumo

An unusual photooxidation of a coordinated 4-mercaptopyridine (SpyH) ligand in the {[}Ru(Hmctpy)(dmbpy)(kappa S-SpyH)](2+) complex (Hmctpy = 4'-carboxy-2,2';6',2 `'-terpyridine, dmbpy = 4,4'-dimethyl-2,2'-bipyridine) takes place under visible and UV irradiation, in aerated acetonitrile. The {[}Ru(mctpy)(dmbpy)(kappa S-SO(2)py)] sulfinato product has been characterized by a variety of methods, including X-ray diffraction which supports the presence of the Ru-kappa S-SpyH isomer in the starting complex. The photooxidation of the 4-mercaptopyridine ligand enhances the back-bonding interactions in the complex by means of the strongly acceptor 4-pyridinesulfinato-SO(2)py species, increasing the redox potential of the Ru(III)/Ru(II) couple significantly from 1.23 to 1.62 V. It also led to pronounced changes in the electronic and NMR spectra of the complexes, corroborated by DFT and ZINDO-S calculations. A possible mechanism based on referenced data of photooxidation has been proposed, which involves the formation of a reactive oxygen species and intermediate endoperoxide species, yielding a very stable Ru-sulfinato product. This novel species exhibits stronger luminescence (Phi(f) = 0.004) than the starting complex under UV excitation. (AU)

• Processo FAPESP: 14/25770-6 - Novas fronteiras em reações de acoplamento cruzado mediadas por paládio: associando catálise enantiosseletiva, ativações C-H, novos materiais e reações em fluxo visando alta eficiência e sustentabilidade em processos sintéticos
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• Processo FAPESP: 15/01491-3 - Estudo teórico das reações de acoplamento-cruzado: catálise homogênea e heterogênea
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