Mercury complexes pyridine oxide

An early procedure used triethyl phosphate directly on the diketone, but better yields are obtained by the oxidation of the corresponding dihydrazone 42 The oxidant may be mercury(n) oxide, which is rather expensive 43 alternatively copper(i) chloride in dichloromethane and pyridine is oxidised with oxygen gas, and the derived complex is then used to oxidise the dihydrazone to the acetylenic group with the evolution of nitrogen.44 The reaction is illustrated by the conversion of benzil dihydrazone into diphenylacetylene (Expt 5.25). 

The preparation and crystal structure determination of mercury(i) complexes of composition Hg2L2X2, Hg2L4X2, and Hg2L6X2 have been described,178-180 where L = 3-chloropyridine, pyridine N-oxide, and triphenylphosphine oxide, respectively. 

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