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Treatment of chromium hexacarbonyl with sodium cyclopentadienide gives Na + [Cr(CO) 3 (C 5 H 5)] −. Oxidation of this salt affords cyclopentadienylchromium tricarbonyl dimer ((C 5 H 5) 2 Cr 2 (CO) 6). This complex is distinctive because it exists in measurable equilibrium with the monometallic Cr(I) radical •Cr(CO) 3 (C 5 H 5).
Chromium compounds are compounds containing the element chromium (Cr). Chromium is a member of group 6 of the transition metals. The +3 and +6 states occur most commonly within chromium compounds, followed by +2; charges of +1, +4 and +5 for chromium are rare, but do nevertheless occasionally exist. [3] [4]
The organochromium compound (phenylmethoxycarbene)pentacarbonylchromium, Ph(OCH 3)C=Cr(CO) 5 was the first carbene complex to be crystallographically characterized by Fischer in 1967 (now called a Fischer carbene). [14] The first ever carbyne, this one also containing chromium, made its debut in 1973. [15]
It can be prepared by treating chromium metal with fluorine at 400 °C and 200 bar pressure. The peroxochromate(V) is another example of the +5 oxidation state. Potassium peroxochromate (K 3 [Cr(O 2) 4]) is made by reacting potassium chromate with hydrogen peroxide at low temperatures. This red brown compound is stable at room temperature but ...
chromium: Cr −4 −2 ... to-oxidation-state ... bs bt bu bv bw bx by bz ca cb cc cd ce cf cg ch ci cj ck cl cm cn co cp cq cr cs ct cu cv cw cx cy cz da db dc dd de ...
Chromium(III) oxide is amphoteric. Although insoluble in water, it reacts with acid to produce salts of hydrated chromium ions such as [Cr(H 2 O) 6] 3+. [11] It is also attacked by concentrated alkali to yield salts of [Cr(OH) 6] 3−. When heated with finely divided carbon or aluminium, it is reduced to chromium metal: Cr 2 O 3 + 2 Al → 2 Cr ...
Commonly three electrons are added to a chromium atom, reducing it to oxidation state +3. In acid solution the aquated Cr 3+ ion is produced. Cr 2 O 2− 7 + 14 H + + 6 e − → 2 Cr 3+ + 7 H 2 O ε 0 = 1.33 V. In alkaline solution chromium(III) hydroxide is produced. The redox potential shows that chromates are weaker oxidizing agent in ...
Oxidation states are typically represented by integers which may be positive, zero, or negative. In some cases, the average oxidation state of an element is a fraction, such as 8 / 3 for iron in magnetite Fe 3 O 4 . The highest known oxidation state is reported to be +9, displayed by iridium in the tetroxoiridium(IX) cation (IrO + 4). [1]