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... 

A complementary access to alkoxy- and aminocarbene complexes ( Semmelhack-Hegedus route ) involves the addition of the pentacarbonylchromate dianion 18 (obtained from the reduction of hexacarbonylchromium with C8K) to carboxylic acid chlorides and amides [27] (Scheme 10). While alkylation of acyl chromate 19 leads to alkoxycarbene complexes 12, addition of chromate dianion 18 to carboxylic amides generates the tetrahedral intermediates 20, which are deoxygenated by trimethylsilyl chloride to give amino carbene complexes 14. 

K. Ofele, l,3-Dimethyl-4-imidazolinyliden-(2)-pentacarbonylchrom - Ein neuer Uber-gangsmetall-Carben-Komplex, J. Organomet. Chem. 12, P42-P43 (1968). 

H. Werner, E. O. Fischer, B. Heckl, and C. G. Kreiter, Kinetik und Mechanismus der Aminolyse von (Methoxyphenylcarben)pentacarbonylchrom(O) - eine Reaktion 4. Ordnung mit negativer Arrhenius-Aktivierungsenergie, J. Organomet. Chem. 28, 367-389 (1971). 

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. 

Reaction of the pentacarbonylchromate(-II) anion with water yields dihydrogen ... 

POTASSIUM pi-HYDRIDO-BIS[PENTACARBONYLCHROMATE(0)] AND POTASSIUM H-HYDRIDO-BIS[PENTACARBONYLTUNGSTATE(0)]... 

Pentacarbonylchromate [Cr(CO)s ] or the iron hydride, HFe(CO)4, can induce alkylation and arylation of carbonyl compounds and active methylene compounds by aldehydes (Cainelli et al, 1973, 1975). The iron... 

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