Photochemical reactions Pentacarbonyl derivatives When heated or UV-irradiated in
tetrahydrofuran (THF) solution, converts to with loss of one CO ligand. The THF ligand is readily displaced. Often the THF complex is generated and used in situ. UV-irradiation of frozen solutions of chromium hexacarbonyl affords a variety of labile adducts, including labile but complexes with some noble gases.
Photodimerization of norbornadiene Norbornadiene was dimerized photochemically in the presence of , similarly to other metal complexes like Iron pentacarbonyl|, Nickel tetracarbonyl|, and Cobalt tricarbonyl nitrosyl|.
Arene derivatives Heating a solution of in an
aromatic solvent results in replacement of three CO ligands. The reactions are especially favorable for electron-rich arenes: : The products are "
piano stool complexes". These species are typically yellow solids. One example is
(benzene)chromium tricarbonyl.
Fischer carbenes Alkyl and aryl
organolithium reagents (RLi) add to to give anionic
acyl complexes. These anionic species in turn react with
alkylating agents such as
trimethyloxonium tetrafluoroborate to form , where R stands for
alkyl, to give
Fischer carbene complexes: :
Cyclopentadienyl derivatives Treatment of chromium hexacarbonyl with
sodium cyclopentadienide gives . Oxidation of this salt affords
cyclopentadienylchromium tricarbonyl dimer (). This complex is distinctive because it exists in measurable equilibrium with the monometallic Cr(I) radical .
Ligand-transfer reactions A unique double ligand-transfer reaction was reported with using
chromium trichloride and chromium hexacarbonyl. In reactions,
potassium perrhenate () is reduced and carbonylated by the chromium reagents and undergoes Cyclopentadienyl anion| ligand-transfer to afford complex derivatives.
Reduction Chromium hexacarbonyl reacts with
sodium electride in ammonia to give sodium pentacarbonylchromate(-II) and sodium
acetylenediolate. ==Safety==