Photochemistry of deprotonated rhenium(I) (3,3′-dihydroxy-2,2′-bipyridine) tricarbonyl chloride. Photoisomerization at the chelate in basic solution

• The complex [bipy(OH)2]Re(CO)3Cl is deprotonated to {[bipy(OH)(O)]Re(CO)3Cl}.
• This anion is light sensitive in solution.
• The photolysis leads to an isomerization at the chelate.
• By rotation of one of the pyridyl rings the coordination changes from N,N to N,O.
• This assumption is supported by various observations such as NMR and IR measurements.

In basic solution the complex Re(I) [bipy(OH)2] (CO)3Cl with bipy(OH)2 = 3,3′-dihydroxy-2,2′-bipyridine is deprotonated at one of the phenolic OH substituents. Upon irradiation of the anion {Re[bipy(OH)(O)] (CO)3Cl}− the yellow solution becomes reddish brown. It is suggested that the photolysis is associated with an isomerization at the chelate from N,N to N,O coordination.

Photoisomerization at the chelate.Figure optionsDownload as PowerPoint slide