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| | Hi there, I am Andrew Berryhill. To perform lacross is the factor I love most of all. My spouse and I live in Mississippi and I love every working day living right here. My working day occupation is a journey agent.<br><br>My web-site :: free psychic reading ([http://www.skullrocker.com/blogs/post/10991 http://www.skullrocker.com/blogs/post/10991]) |
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| | Name = Krogmann's salt
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| | IUPACName = Dipotassium tetracyanoplatinate bromide trihydrate
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| | OtherNames = Potassium tetracyanoplatinate bromide trihydrate
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| | Name = Krogmann's salt
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| | Section1 = {{Chembox Identifiers
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| | Section2 = {{Chembox Properties
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| | Formula = K<sub>2</sub>Pt(CN)<sub>4</sub>Br<sub>0.3</sub>
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| | MolarMass = 401.3227 g/mol
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| | Appearance = Copper-colored crystalline solid
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| | Density =
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| | Section3 = {{Chembox Structure
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| | Coordination = [[Square planar]]
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| | CrystalStruct = [[Tetragonal]]
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| | Dipole =
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| | Section7 = {{Chembox Hazards
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| '''Krogmann's salt''' is a mixed-[[valence (chemistry)|valence]] [[square planar]] [[coordination complex]] of [[platinum]] and [[cyanide]] bonded through linear platinum metal chains, sometimes described as molecular wires.
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| Although the term Krogmann’s salt most commonly refers to a platinum metal [[Coordination complex|complex]] of the formula K<sub>2</sub>[Pt(CN)<sub>4</sub>X<sub>0.3</sub>] where X is usually [[bromine]] (or sometimes [[chlorine]]), a number of non-[[stoichiometric]] metal salts containing the [[anionic]] complex [Pt(CN)<sub>4</sub>]<sup>2-</sup> can also be characterized under the blanket term “Krogmann’s salts.”
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| Modeled as an infinite [[one-dimensional]] molecular chain of platinum atoms, the high [[anisotropy]] and restricted [[dimensionality]] of Krogmann’s salt and related compounds are becoming increasingly attractive properties for many facets of [[nanotechnology]].<ref name="Bera">{{cite journal |author= Bera, J. K.; Dunbar, K. R. |journal= [[Angew. Chem. Int. Ed.]] |year= 2002 |volume= 41 |issue= 23 |pages= 4453–4457 |title= Chain Compounds Based on Transition Metal Backbones: New Life for an Old Topic |doi= 10.1002/1521-3773(20021202)41:23<4453::AID-ANIE4453>3.0.CO;2-1 |pmid=12458505}}</ref>
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| ==History==
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| Krogmann’s salt was first synthesized by Dr. Klaus Krogmann in the late 1960s at the [[University of Stuttgart]] in [[Germany]]. Dr. Krogmann published the original journal article documenting the synthesis and characterization of the salt in 1969.<ref name="Krogmann">{{ cite journal |author= Krogmann, K. |journal= [[Angew. Chem.]] |year= 1969 |volume= 81 |issue= 1 |pages= 10–17 |title= Planare Komplexe mit Metall-Metall-Bindungen |doi= 10.1002/ange.19690810103 |language= German }} {{ cite journal |author= Krogmann, K. |journal= [[Angew. Chem. Int. Ed. Engl.]] |year= 1969 |volume= 8 |issue= 1 |pages= 35–42 |title= Planar Complexes Containing Metal-Metal Bonds |doi= 10.1002/anie.196900351 }}</ref>
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| ==Structure and physical properties==
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| [[File:Anion-chains-from-cyanoplatinates-compared-3D-balls.png|thumb|right|330px|''n''[Pt(CN)<sub>4</sub>]<sup>2−</sup> → ([Pt(CN)<sub>4</sub>]<sup>1.7−</sup>)<sub>''n''</sub>]]
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| Krogmann’s salt is a series of partially [[oxidized]] tetracyanoplatinate complexes linked by the platinum-platinum bonds on the top and bottom faces of the planar [Pt(CN)<sub>4</sub>]<sup>n-</sup> anions. This salt forms infinite stacks in the solid state based on the overlap of the d<sub>z2</sub> [[atomic orbital|orbitals]].<ref name="Bera"/>
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| Krogmann’s salt has a [[tetragonal]] crystal structure with a Pt-Pt distance of 2.880 [[angstroms]], which is much shorter than the metal-metal bond distances in other planar platinum complexes such as Ca[Pt(CN)<sub>4</sub>]·5H<sub>2</sub>O (3.36 angstroms), Sr[Pt(CN)<sub>4</sub>]·5H<sub>2</sub>O (3.58 angstroms), and Mg[Pt(CN)<sub>4</sub>]·7H<sub>2</sub>O (3.16 angstroms).<ref name="Krogmann"/><ref>{{ cite journal |author= Krogmann, K.; Hausen, H. D. Z. |journal= Z. Anorg. Allg. Chem. |year= 1968 |volume= 358 |pages= 67 |title= Pt-Chain Structures. 1. Potassium Tetracyanoplatinate Violets K<sub>2</sub>[Pt(CN)<sub>4</sub>]X<sub>0,3</sub>·2,5H<sub>2</sub>O (X=Cl,Br) }}</ref> The Pt-Pt distance in Krogmann's salt is only 0.1 angstroms longer than in platinum metal.
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| Each [[unit cell]] contains a site for Cl<sup>-</sup>, corresponding to 0.5 Cl<sup>-</sup> per Pt. However, this site is only filled 64% of the time, giving 0.32 Cl<sup>-</sup> per Pt in the actual compound. Because of this, the [[oxidation number]] of Pt does not rise above +2.32.<ref name="Krogmann"/>
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| Krogmann’s salt has no recognizable phase range and is characterized by broad and intense intervalence bands in its electronic spectra.<ref name="Clar">{{ cite journal |author= Clar, R. J. H.; Cround, V. B.; Khokhar, A. R. |journal= [[Inorg. Chem.]] |year= 1987 |volume= 26 |issue= 20 |pages= 3284–3290 |title= Neutral chain chloride- and bromide-bridged platinum(II,IV) complexes of 1,2-diaminocyclohexane: synthesis and electronic, infrared, Raman, and resonance Raman studies |doi= 10.1021/ic00267a014 }}</ref>
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| ==Chemical properties==
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| One of the most widely researched properties of Krogmann’s salt is its unusual electric conductance. Because of its linear chain structure and overlap of the platinum <math>d_{z^2}</math> orbitals, Krogmann’s salt is an excellent conductor of [[electricity]].<ref name="Bera"/> This property makes it an attractive material for nanotechnology.<ref name="Wu">{{ cite journal |author= Wu, D. Y.; Zhang, T. L. |journal= [[Prog. Chem.]] |year= 2004 |volume= 16 |issue= 6 |pages= 911–917 |title= Recent developments in linear chain clusters of low-valent platinum group metals |doi= |language= Chinese }}</ref>
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| ==Preparation==
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| The usual preparation of Krogmann's salt involves the evaporation of a 5:1 [[Mole (unit)|molar]] ratio mixture of the salts K<sub>2</sub>[Pt(CN)<sub>4</sub>] and K<sub>2</sub>[Pt(CN)<sub>4</sub>Br<sub>2</sub>] in water to give copper-colored needles of K<sub>2</sub>[Pt(CN)<sub>4</sub>]Br<sub>0.32</sub>·2.6 H<sub>2</sub>O.
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| ::5K<sub>2</sub>[Pt(CN)<sub>4</sub>] + K<sub>2</sub>[Pt(CN)<sub>4</sub>Br<sub>2</sub>] + 15.6 H<sub>2</sub>O → 6K<sub>2</sub>[Pt(CN)<sub>4</sub>]Br<sub>0.32</sub>·2.6 H<sub>2</sub>O | |
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| Because excess Pt<sup>II</sup> or Pt<sup>IV</sup> complex crystallizes out with the product when the reactant ratio is changed, the product is therefore well defined, although [[non-stoichiometric]].<ref name="Krogmann"/>
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| ==Uses==
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| Although there was a large body of research and literature generated on molecular wire-type metal complexes through the mid-1980s, interest in stacked metal-metal bonds saw a decline until only very recently.
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| Due to the explosion of nanotechnology in the last few years, many researchers have taken a renewed interest in Krogmann’s salt and its related compounds due to their high anisotropy, restricted dimensionality, and unique [[Electrical conductance|conductance]] properties.
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| A new group of platinum chains based on alternating cations and anions of [Pt(CNR)<sub>4</sub>]<sup>2+</sup> (R = ''i''Pr, ''c-''C<sub>12</sub>H<sub>23</sub>, ''p-''(C<sub>2</sub>H<sub>5</sub>)C<sub>6</sub>H<sub>4</sub>) and [Pt(CN)<sub>4</sub>]<sup>2-</sup> is undergoing current research.<ref name="Bera"/> These may be able to be used as [[vapochromic]] [[sensor]] materials, or materials which change color when exposed to different vapors.<ref name="Grate">{{ cite journal |author= Grate, J. W.; Moore, L. K.; Janzen, D. E.; Veltkamp, D. J.; Kaganove, S.; Drew, S. M.; Mann, K. R. |journal= [[Chem. Matter.]] |year= 2002 |volume= 14 |issue= 3 |pages= 1058–1066 |title= Steplike Response Behavior of a New Vapochromic Platinum Complex Observed with Simultaneous Acoustic Wave Sensor and Optical Reflectance Measurements |doi= 10.1021/cm0104506 }}</ref><ref name="Buss '02">{{cite journal |author= Buss, C.E.; Mann, K.R. |journal= [[J. Am. Chem. Soc.]] |year= 2002 |volume= 124 |issue= 6 |pages= 1031–1039 |title= Synthesis and Characterization of Pt(CN-''p''-(C<sub>2</sub>H<sub>5</sub>)C<sub>6</sub>H<sub>4</sub>)<sub>2</sub>(CN)<sub>2</sub>, a Crystalline Vapoluminescent Compound That Detects Vapor-Phase Aromatic Hydrocarbons |doi= 10.1021/ja011986v }}</ref><ref name="Buss '98">{{ cite journal |author= Buss, C.E.; Anderson, C.E.; Pomije, M. K.; Lutz, C. M.; Britton, D.; Mann, K. R. |journal= [[J. Am. Chem. Soc.]] |year= 1998 |volume= 120 |issue= 31 |pages= 7783–7790 |title= Structural Investigations of Vapochromic Behavior. X-ray Single-Crystal and Powder Diffraction Studies of [Pt(CN-''iso''-C<sub>3</sub>H<sub>7</sub>)<sub>4</sub>][M(CN)<sub>4</sub>] for M = Pt or Pd |doi= 10.1021/ja981218c }}</ref>
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| Similar to Krogmann’s platinum salt, it has been shown that it is possible to stabilize metal chains with only [[Saturation (chemistry)|unsaturated]] [[hydrocarbons]], or olefins. Current research indicates that mononuclear [[Palladium|Pd]]<sup>0</sup> and Pd<sup>II</sup> react with [[conjugated system|conjugated]] [[polyenes]] to give linear chains of Pd-Pd bonds protected by a “π-electron sheath.”<ref name="Bera"/><ref name="Mino">{{ cite journal |author= T., Mino, Y., Mochizuki, E., Kai, Y., Kurosawa, H. |journal= [[J. Am. Chem. Soc.]] |year= 2001 |volume= 123 |issue= 28 |pages= 6927–6928 |title= Reversible Interconversion between Dinuclear Sandwich and Half-Sandwich Complexes: Unique Dynamic Behavior of a Pd-Pd Moiety Surrounded by an sp<sup>2</sup>-Carbon Framework |doi= 10.1021/ja010027y }}</ref>
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| Not only do these olefin-stabilized metal chains constitute a significant contribution to the field of [[organometallic chemistry]], both the complex’s metal atom structures and the [[olefin]] [[ligands]] themselves can conduct a current.<ref name="Bera"/><ref name="Murahashi '00">{{ cite journal |author= Murahashi, T.,Nagai, Okuno, T., Matsutani, T., Kurosawa, H. |journal= [[Chem. Commun.]] |year= 2000 |issue= 17 |pages= 1689–1690 |title= Synthesis and ligand substitution reactions of a homoleptic acetonitrile dipalladium(I) complex |doi= 10.1039/b004726k }}</ref> The prospect of creating molecular wires of conducting [[organic compound|organic]] and [[inorganic]] constituents has intriguing possibilities for future research, especially in [[microbiology]], nanotechnology, and organic circuitry.
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| ==References==
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| <references/>
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| {{Platinum compounds}}
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| [[Category:Cyanides]]
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| [[Category:Potassium compounds]]
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| [[Category:Platinum compounds]]
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| [[Category:Metal halides]]
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| [[Category:Electrical conductors]]
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| [[Category:Mixed valence compounds]]
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| [[Category:Non-stoichiometric compounds]]
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Hi there, I am Andrew Berryhill. To perform lacross is the factor I love most of all. My spouse and I live in Mississippi and I love every working day living right here. My working day occupation is a journey agent.
My web-site :: free psychic reading (http://www.skullrocker.com/blogs/post/10991)