Pentacarbonyl(fluoroisocyanoacetonitrile)chromium 4 is obtained from the reaction of pentacarbonyl(trifluoroethenyl isocyanide)chromium 3 with ammonia. Pentacarbonyl(2,3,3,3-tetrafluoro-2-isocyanopropionitrile)chromium 5 is prepared by radical alkylation of tetraethylammonium[pentacarbonyl(cyano)chromate 1. The structure of 4 has been elucidated by X-ray crystallography. (C) 1999 Elsevier Science S.A. All rights reserved.