Reactions of pentafluorophenyl isocyanide with pentacarbonyl(pi(2)-cis-cyclooctene)chromium, tricarbonyl(eta(6)-cycloheptatriene)tungsten, and tetracarbonylnickel yield pentacarbonyl(pentafluorophenyl isocyanide)chromium I, mer-tricarbonyl-tris(pentafluorophenyl isocyanide) tungsten II, and tetrakis(pentafluorophenyl isocyanide)nickel III, respectively. The meridial structure of tricarbonyl-tris(pentafluorophenyl isocyanide)tungsten was elucidated by X-ray crystallography. The [2 + 1] cycloaddition reaction of pentafluorophenyl isocyanide with the diphosphene R=P=P=R [R=C(SiMe3)(3)] yields the three membered heterocyclic diphosphirane imine IV. The photolysis of pentafluorophenyl isocyanide in the presence of [bis(diisopcopylamino)phophino]-(trimethylsilyl) diazomethane yields 1-pentafluorophenyl-2,4-bis(diisopropylamino)-3-trimethylsilyl-1,2-azaphosphetine V according to the results of an X-ray structure analysis at -158 degrees C, (C) 1998 Elsevier Science S.A. All rights reserved.