[elt2112]

I was wondering if anyone could help me with this question. Is cooperative binding just that two species bind instead of one? I know the Na⁺ will coordinate with the 5 O atoms. Will the Ru²⁺ just coordinate to the nitrogen atoms?

[pgk]

Na cation does not chelate with the oxygens of the crown ether, contrary to Ru cation that easily chelates. However, RuO2 (the major source) is not water soluble and therefore it cannot penetrate into the crown ether cavity. Thus, by transforming RUO2 to the water soluble Na2RuO4, penetration into the crown ether cavity and successful chelation can be effectuated. Besides, sodium can chelate with the aromatic nitrogens, under specific conditions and additionally help the overall chelation.
Question: How RuO2 can be transformed to Na2RuO4?

[sjb]

Na cation does not chelate with the oxygens of the crown ether, contrary to Ru cation that easily chelates. However, RuO₂ (the major source) is not water soluble and therefore it cannot penetrate into the crown ether cavity. Thus, by transforming RuO₂ to the water soluble Na₂RuO₄, penetration into the crown ether cavity and successful chelation can be effectuated. Besides, sodium can chelate with the aromatic nitrogens, under specific conditions and additionally help the overall chelation.

Do you have a source for this? I thought rather the reverse, that the sodium cation chelated to the crown ether (cf K-18-crown-6) and the Ru to the bipy, like in many photoelectric cells?

[pgk]

Better written:
Na cation does not easily chelate with the oxygens of the crown ether without a stabilizer (organometallics , Re compounds etc.), contrary to Ru cation that easily chelates. However, RuO2 (the major source) is not water soluble and therefore it cannot penetrate into the crown ether cavity. Thus, by transforming RUO2 to the water soluble Na2RuO4, penetration into the crown ether cavity and successful chelation can be effectuated. Besides, rutehnium can chelate with the aromatic nitrogens, under specific conditions and additionally help the overall chelation by forming a Ru-diimine complex.
For further indicative reading:
http://chemgroups.northwestern.edu/hupp/Publications/73.pdf
http://pubs.acs.org/doi/abs/10.1021/je2006924
http://pubs.rsc.org/en/Content/ArticleLanding/1999/DT/a902358e#!divAbstract
http://pubs.rsc.org/en/Content/ArticleLanding/2002/AN/B206514M#!divAbstract http://pubs.acs.org/doi/abs/10.1021/ic7019582?journalCode=inocaj

Thank's for the remarks