Iron tetracarbonyl dihydride

DR. JACK NORTON (Colorado State University) One interesting result that has just appeared is Ray Sweany s report of photochemical hydrogen loss from iron tetracarbonyl dihydride [Sweany, R. L. J. Am. Chem. Soc. 1981, 103, 2410]. This system is very close to the case in which I claimed some years ago that this process did not occur. First of all, do you have any possible explanations for the differing behavior Why is Sweany s result different from the result of Tony Rest Second, if hydrogen eliminates in a concerted process such as you have just described, why don t other species such as cis-methyl groups do likewise ... 

Fe(CO)4K2 Iron tetracarbonyl dihydride, potassium salt, 2 244 [Fe(C204)3]K3 3H20 Potassium tri-oxalatoferrate(III), 1 36 [Fe(C6H6N)4]Cl2 Tetrapyridine-iron(II) chloride, 1 184 FeClj Iron(III) chloride, 3 190 4 124... 

Fe(CO)4H2 Iron tetracarbonyl dihydride, 2 243 potassium salt, 2 244 sodium salts, 7 194, 197 [Fe(C204)3]K3-3H20 Potassium trioxalatoferrate(III), 1 36 FeC6Hs(CO)2l Cyclopentadienyl-iron dicarbonyl iodide, 7 110 FeC6H5(CO)2Na Cyclopentadi-enyliron dicarbonyl, sodium derivative, 7 112 [FeC6H5(CO)2]2 Cyclopentadi-enyliron dicarbonyl, dimer, 7 110... 

The product caught in this trap may be contaminated with iron pentacarbonyl and kerosene. After all the carbon dioxide is swept out, a second trap, cooled with liquid air, is attached to the train. With a slow stream of carbon monoxide passing, the first trap is allowed to warm up to — 10°, and all the iron tetracarbonyl dihydride is swept into the trap cooled with liquid air. The iron tetracarbonyl dihydride collects as a white crystalline solid. 

Iron tetracarbonyl dihydride melts at —70°, and it has a vapor pressure of 11 mm. at —10° (extrapolated). However, it is very unstable when pure and decomposes below —10°. In a current of carbon monoxide, the dilute vapors do not decompose even at room temperature. In alkaline solution, the potassium salt, K2Fe(CO)4, is stable but is very sensitive to oxidation by air. 

Vacuum technique may be used instead of sweeping, but in the absence of carbon monoxide the iron tetracarbonyl dihydride is much more likely to decompose in the wanner part of the apparatus. 

Ni(CO)4 Nickel tetracarbonyl [Co(CO)4]2 Dicobalt octacarbonyl CoNO(CO)3 Cobalt nitrosyl tricarbonyl H2Fe(CO)4 Iron tetracarbonyl dihydride... 

F2O Oxygen fluoride, 1 109 F4C Carbon tetrafluoride, 1 34 FeS SuEur(VI) fluoride, 1 121 FeSe Selenium(VI) fluoride, 1 121 FeTe Tellurium(VI) fluoride, 1 121 Fe(CO)4H2 Iron tetracarbonyl dihydride, 2 243... 

Cr(C6H6)2 dibenzenechromium The handling of carbonyl derivatives in the examples will be noted names/such as di-iron ennea-carbonyl (with its irregular final -yl ending) and iron carbonyl hydride or iron tetracarbonyl dihydride can well be spared. 

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