使用者:DoroWolf/沙盒/試亞鐵靈

DoroWolf/沙盒/試亞鐵靈
識別
CAS號	14634-91-4
PubChem	84567
ChemSpider	76289
SMILES	[Fe+2].[O-]S([O-])(=O)=O.n3c2c1ncccc1ccc2ccc3.n3c2c1ncccc1ccc2ccc3.n1c3c(ccc1)ccc2cccnc23;
InChI	1/3C12H8N2.Fe.H2O4S/c31-3-9-5-6-10-4-2-8-14-12(10)11(9)13-7-1;;1-5(2,3)4/h31-8H;;(H2,1,2,3,4)/q;;;+2;/p-2;
InChIKey	CIWXFRVOSDNDJZ-NUQVWONBAU
性質
化學式	C36H24FeN62+
摩爾質量	596.27 g·mol⁻¹
	若非註明，所有數據均出自標準狀態（25 ℃，100 kPa）下。

試亞鐵靈（英語：Ferroin）是一種配位化合物，化學式為[Fe(o-phen)₃]SO₄，其中o-phen為1,10-菲囉啉的縮寫，是一種雙齒配體。

氧化還原指示劑

這種配位化合物在分析化學中用作指示劑。^[1]活性成分是[Fe(o-phen)₃]²⁺離子，它是一種發色團，可以被氧化成鐵衍生物[Fe(o-phen)₃]³⁺。在1M H₂SO₄中，此氧化還原變化的電位為+1.06 V。它是一種受歡迎的氧化還原指示劑，用於可視化振盪B-Z反應。

試亞鐵靈適合作為氧化還原指示劑，因為顏色變化是可逆、非常明顯且快速的，並且試亞鐵靈溶液在高達60 °C的溫度下是穩定的。它是陶瓷測量法中使用的主要指示劑。^[2]

Nitroferroin, the complex of iron(II) with 5-nitro-1,10-phenanthroline, has transition potential of +1.25 volts. It is more stable than ferroin, but in sulfuric acid with Ce⁴⁺ ion it requires significant excess of the titrant. It is however useful for titration in perchloric acid or nitric acid solution, where cerium redox potential is higher.^[2]

通過調整鄰二氮菲核上甲基的位置和數量，鐵-鄰二氮菲絡合物的氧化還原電位可以在 +0.84 V 和 +1.10 V 之間變化。^[2]

製備

試亞鐵靈可以通過將鄰二氮菲與硫酸亞鐵在水中結合來製備。

3 phen + Fe²⁺ → [Fe(phen)₃]²⁺

鐵是低自旋和具有 D 3對稱性的八面體。這種亞鐵絡合物的強烈顏色來自金屬到配體的電荷轉移轉變。

Reaction kinetics

When sulfuric acid (H₂SO₄) is added to a solution of [Fe(phen)₃]²⁺, it causes the iron complex to decompose as described by the following reaction:

[Fe(phen)₃]²⁺_(aq) + 3 H₃O⁺_(l) → Fe²⁺_(aq) + 3 phenH⁺_(aq) + 3 H₂O_(l)

Thanks to the high molar absorptivity of ferroin (a measure of how much the molecule interacts with light), this decomposition can be observed measuring the solution absorbance over time.

The rate of decomposition is first order in [Fe(phen)₃]²⁺, and zeroth order in 3 H₃O⁺. That means the rate law is:

Decrease in ferroin over Time = k [Ferroin]

where k is the reaction constant, and [Ferroin] is the concentration of ferroin. [H₃O⁺] does not show up in the rate law. The concentration of ferroin over time decreases with exponential decay.

References

^ Harris, D. C. Quantitative Chemical Analysis 4th. New York, NY: W. H. Freeman. 1995. ISBN 978-0-7167-2508-4.
^ ^2.0 ^2.1 ^2.2 Handbook on the Physics and Chemistry of Rare Earths. Elsevier. 2006: 289–. ISBN 978-0-08-046672-9.

[1] Harris, D. C. Quantitative Chemical Analysis 4th. New York, NY: W. H. Freeman. 1995. ISBN 978-0-7167-2508-4.

[physchemrare-2] 2.0 ^2.1 ^2.2 Handbook on the Physics and Chemistry of Rare Earths. Elsevier. 2006: 289–. ISBN 978-0-08-046672-9.

[1]

[2]