5.04 Chromium Compounds with CO or Isocyanides

A review with 684 references covering the period 1993–2004 summarising the syntheses, structures and reactivity of molecules possessing a chromium carbonyl or chromium isonitrile linkage. The major topics discussed are complexes in which there is a chromium–main group element bond, and arene chromium tricarbonyl complexes with emphasis on the stereochemical and electronic effects of complexation on the chemistry of the arene. Recent work on chromium hydrides and on (cyclopentadienyl)Cr(CO)3 radicals and the formation of fulvalene complexes is also discussed. The use of carbene complexes as precursors to polycyclic aromatics is summarised, and the interconversion of chromium isonitriles and their isomeric nitrogen-stabilised Fischer-type carbenes is outlined. Potential applications such as chromium-containing conducting polymers, materials with novel non-linear optical properties, biological labelling, and molecular machines are discussed.