A graduate student tried to make o-fluorophenylmagnesium bromide by adding magnesium to...

A graduate student tried to make o-fluorophenylmagnesium bromide by adding magnesium to an ether solution of o-fluorobromobenzene. After obtaining puzzling results with this reaction, she repeated the reaction by using as solvent some tetrahydrofuran that contained a small amount of furan. From this reaction, she isolated a fair yield of the compound that follows. Propose a mechanism for its formation.