“Polyiodide”的意思、由来-开放百科全书

The polyiodides are a class of polyhalogen anions composed entirely of iodine atoms. The most common and simplest member is the triiodide ion, {{chem|I|3|−}}. Other known, larger polyiodides include [I₄]²⁻, [I₅]⁻, [I₇]⁻, [I₈]²⁻, [I₉]⁻, [I₁₀]²⁻, [I₁₀]⁴⁻, [I₁₁]³⁻, [I₁₂]²⁻, [I₁₃]³⁻, [I₁₆]²⁻, [I₂₂]⁴⁻, [I₂₆]³⁻, [I₂₆]⁴⁻, [I₂₈]⁴⁻ and [I₂₉]³⁻.^[1]

Preparation

The polyiodides can be made by addition of stoichiometric amounts of I₂ to solutions containing I⁻ and {{chem|I|3|−}}, with the presence of large counter-cations to stabilize them. For example, KI₃·H₂O can be crystallized from a saturated solution of KI when a stoichiometric amount of I₂ is added and cooled.^[2]

Structure

Polyiodides are characterized by their highly complex and variable structures, and can be considered as associations of I₂, I⁻, and {{chem|I|3|−}} units. Discrete polyiodides are usually linear, reflecting the origin of the ion. The more complex two- or three-dimensional network structures of chains and cages are formed as the ions interact with each other, with their shapes depending on their associated cations quite strongly. The table below lists the polyiodide salts which have been structurally characterized, along with their counter-cation.^[3]

Structure of higher polyiodides

Anion

Counter-cation

Structural description

[I₃]⁻

Cs⁺

linear

[I₄]²⁻

[Cu(NH₃)₄]²⁺

symmetric linear array of iodine atoms^[4]

[I₅]⁻

[EtMe₃N]⁺

V-shaped with polymeric layers

[EtMePh₂N]⁺

V-shaped with isolated [I₅]⁻ ions

[I₇]⁻

[Ag(18aneS₆)]⁺

an anionic network derived from a primitive rhombohedral lattice of iodide ions bridged by I₂ molecules

[I₈]²⁻

[Ni(phen)₃]²⁺

I|3|−}}·I₂·{{chem|I|8|−}}] or [{{chem|I|3|−}}·{{chem|I|5|−}}]

[I₉]⁻

[Me₂ⁱPrPhN]⁺

14-membered ring tied by two I₂ bridges to give 10-membered rings

[Me₄N]⁺

I|3|−}} and I₂ units

[I₁₀]²⁻

[Cd(12-crown-4)₂]²⁺

I|3|−}} units linked by two I₂ molecules

[I₁₁]³⁻

[(16aneS₄)PdIPd(16aneS₄)]³⁺

14-membered ring (9.66 × 12.64 Å) around the complex cation, with the rings interlink further to give an infinite 2D sheet

[I₁₂]²⁻

[Ag₂(15aneS₅)₂]²⁺

extended 3D spiral superstructure supported by Ag–I bonds and weak I···S interactions

[Cu(Dafone)₃]²⁺

planar configuration

[I₁₃]³⁻

[Me₂Ph₂N]⁺

consists of zigzag chains of I⁻ and I₂

[I₁₆]²⁻

[Me₂Ph₂N]⁺

centrosymmetric arrangement of [I₇⁻·I₂·I₇⁻]

[ⁱPrMe₂PhN]⁺

the anion forms 14-membered rings catenated by I₂ molecules, which further link into layers with 10- and 14-membered rings

[I₂₂]⁴⁻

[MePh₃P]⁺

two "L"-shaped [I₅]⁻ units linked by an I₂ molecule and completed by two end-on [I₅]⁻ groups

[I₂₆]³⁻

[Me₃S]⁺

consists of [I₅]⁻ and [I₇]⁻ ions with intercalated I₂ molecules

[I₂₆]⁴⁻

Cp*₂Fe⁺

− ions, with I₂ bridges on all edges and systematically removing {{frac>12}} of the I₂ molecules

[I₂₉]³⁻

Cp₂Fe⁺

I|5|−}})_{{1/2}}·I₂}·{({{chem|I|12|2−}})_{{1/2}}·I₂}·I₂], with [Cp₂Fe]⁺ ions interacting with the anion in the cavities

[I_∞]^δ−

Pyrroloperylene^+•

Infinite polyiodide homopolymer.^[5]

References

1. ^{{cite book| title = Inorganic Chemistry | edition = 3rd| chapter = Chapter 17: The group 17 elements| first1 = Catherine E. | last1 = Housecroft| first2 = Alan G. | last2 = Sharpe| publisher = Pearson| year = 2008| isbn = 978-0-13-175553-6| page = 547}}
2. ^{{cite encyclopedia|title=Potassium triiodide|encyclopedia=Handbook of Preparative Inorganic Chemistry|edition=2nd|editor-first=G.|editor-last=Brauer|publisher=Academic Press|date=1963|location=New York|volume=1|page=294}}
3. ^{{cite book| title = Encyclopedia of Inorganic Chemistry | edition = 2nd| chapter = Chlorine, Bromine, Iodine, & Astatine: Inorganic Chemistry| first = R. Bruce | last = King| publisher = Wiley| year = 2005| isbn = 9780470862100| page = 747}}
4. ^{{cite journal|first1=Per H.|last1=Svensson|first2=Lars|last2=Kloo|title=Synthesis, Structure, and Bonding in Polyiodide and Metal Iodide–Iodine Systems|journal=Chem. Rev.|date=2003|volume=103|issue=5|page=1649–1684|doi=10.1021/cr0204101}}
5. ^{{cite journal |last1=Madhu |first1=Sheri |last2=Evans |first2=Hayden A. |last3=Doan-Nguyen |first3=Vicky V. T. |last4=Labram |first4=John G. |last5=Wu |first5=Guang |last6=Chabinyc |first6=Michael L. |last7=Seshadri |first7=Ram |last8=Wudl |first8=Fred |title=Infinite Polyiodide Chains in the Pyrroloperylene-Iodine Complex: Insights into the Starch-Iodine and Perylene-Iodine Complexes |journal=Angewandte Chemie International Edition |date=4 July 2016 |volume=55 |issue=28 |pages=8032–8035 |doi=10.1002/anie.201601585}}