Mimics of [FeFe]-hydrogenases having two [(μ-adt)Fe_(2)(CO)_(6)] moieties linked through 1,2,3-triazole ringswith polyethylene glycol (PEG) chains [(-OCH_(2)CH_(2)O-)4 (7) and (-OCH_(2)CH_(2)O-)5 (8)] are able to coo...Mimics of [FeFe]-hydrogenases having two [(μ-adt)Fe_(2)(CO)_(6)] moieties linked through 1,2,3-triazole ringswith polyethylene glycol (PEG) chains [(-OCH_(2)CH_(2)O-)4 (7) and (-OCH_(2)CH_(2)O-)5 (8)] are able to coordinateto alkali ions (Na^(+), K^(+)) via the O-PEG atoms and the triazole-N3 positions. Electrocatalytic studies intrifluoroacetic acid (TFA) demonstrate that their catalytic performance is affected by the presence of Na+and K+ salts. The addition of NaPF6 decreases the electrocatalytic activity of 7 and 8 (about 50% reductionof the TOF values). As, in TFA, 7 and 8 could be protonated in both the triazole and adt-amino groups, thereduction in TOF values suggests that NaPF6 inhibits the contribution of the triazolium species to theelectrocatalytic process, likely due to the involvement of the triazole-N3 positions in Na^(+) binding.However, the addition of KPF_(6) either does not change (7) or increases the TOF values (8). ^(1)H NMR titrationexperiments demonstrate that, despite the presence of K^(+) ions in the media, triazolium salts are formed.Therefore, the TOF values should reflect the contribution of species protonated in both the triazole andadt-amino groups to the HER process.展开更多
基金Support for this work from the Ministerio de Ciencia,Innovación y Universidades(Grants PID2022-139177OB-I00 and RED2022-134287-T)is acknowledgedrecipient of an FPU fellowship(FPU16/02062).
文摘Mimics of [FeFe]-hydrogenases having two [(μ-adt)Fe_(2)(CO)_(6)] moieties linked through 1,2,3-triazole ringswith polyethylene glycol (PEG) chains [(-OCH_(2)CH_(2)O-)4 (7) and (-OCH_(2)CH_(2)O-)5 (8)] are able to coordinateto alkali ions (Na^(+), K^(+)) via the O-PEG atoms and the triazole-N3 positions. Electrocatalytic studies intrifluoroacetic acid (TFA) demonstrate that their catalytic performance is affected by the presence of Na+and K+ salts. The addition of NaPF6 decreases the electrocatalytic activity of 7 and 8 (about 50% reductionof the TOF values). As, in TFA, 7 and 8 could be protonated in both the triazole and adt-amino groups, thereduction in TOF values suggests that NaPF6 inhibits the contribution of the triazolium species to theelectrocatalytic process, likely due to the involvement of the triazole-N3 positions in Na^(+) binding.However, the addition of KPF_(6) either does not change (7) or increases the TOF values (8). ^(1)H NMR titrationexperiments demonstrate that, despite the presence of K^(+) ions in the media, triazolium salts are formed.Therefore, the TOF values should reflect the contribution of species protonated in both the triazole andadt-amino groups to the HER process.
