title: Flyover complex
text: # Flyover complex
  
  In organometallic chemistry, a flyover complex features two metals bridged by the fragment $OC(RC=CR)_2.$ Some flyover complexes are symmetrical and some are not.
  
  Common examples are the iron carbonyl derivatives, which are typically air-stable, soluble in nonpolar solvents, and red-orange in color. These diiron complexes arise by the reaction of alkynes with iron carbonyls. Such reactions are known to generate many products, e.g. complexes of cyclopentadienones and para-quinones.
  
  Some ferrole complexes react with tertiary phosphines to give the substituted flyover complex $Fe_2(CO)_5(PR_3)(C_4R_4CO).$ They insert alkynes en route to tropones $(R_6C_7O).$
  
  