Disodium pentacarbonylchromate

Disodium pentacarbonylchromate is prepared by adding a solution of sodium naphthalenide (88 mmol) in THF (160 mL) to chromium hexacarbonyl (40 mmol) in THF (240 mL). The resulting solution of disodium pentacarbonylchromate is transferred to a 500-mL graduated cylinder (to estimate the concentration). This solution can be stored at -20 °C under argon for at least two months. 

In our laboratory in 1968, Ofele (44) treated 1, l-dichloro-2,3-diphenyl-2-cyclopropene with disodium pentacarbonylchromate and, with the concomitant elimination of sodium chloride, he obtained pentacarbony 1(2,3-diphenylcyclopropenylidene) chromium(0). This compound is stable up... 

In addition to the compound classes mentioned so far, cyclopropenylidene complexes have also been reported. The first mononuclear carbene complex not stabilized by a heteroatom in the (X-position was the chromium complex 27, which proved to be unexpectedly stable. This complex was obtained in 20% yield by treatment of 3,3-dichloro-l, 2-diphenylcyclopropene with disodium pentacarbonylchromate at — 20 °C. However, isolation of the complex is easier when it is prepared from 3-ethoxy-l,2-diphenylcyclopropenium tetrafluoroborate. The corresponding molybdenum complex can also be obtained in this way. 

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