Alkyl hydride complexes isotopic scrambling

The reductive elimination of arenes from aryl hydride complexes draws many parallels with the reductive elimination from alkyl hydrides. For example, arene complexes are believed to form from ttie reductive elimination prior to release of the free arene. Studies by Feher and Jones provided compelling evidence for the presence of arene complexes, - and complementary synthetic studies have led to the isolation of closely related "q -arene complexes. " As shown in Equation 8.24, the arylrhodium deuteride complex scrambles deuterium into the aryl ring, just as alkyhnetal deuteride complexes scramble deuterium into the alkyl group. This isotopic exchange presumably occurs by formation of the arene complex shown at the center of Equation 8.24... 

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