Abstract
Tropolonate complexes of Ru(II), Ru(III), and Os(II) with hinokitiol, also termed β-thuljaplicin, or 4-isopropyltropolone, readily formed by chloride and triarylphosphine substitution in RuCl2(PPh3)3 and MHCl(CO)(PR3)3 (M = Ru, R = Ph; M = Os, R = Ph and p-tolyl). The resulting colorful complexes have variable and strong charge transfer bands and also have a surprising combination of stereochemical selectivity and lability. For the Os(II) d6 examples, the tropolone chelate has a fluxionality with a barrier of only 90 kJ/mol for the R = aryl examples, as determined by variable-temperature 31P NMR. Chlorination with N-chlorosuccinimide results in MCl(CO)(hino)(PPh3)2 (M = Ru and Os). Together these results quantify the fluxionality of this important chelate which in turn has consequences for its biochemistry.
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