{{Short description|Materials made of one-dimensional arrays of metal-metal bonded molecules}} [[file:Magnus'-green-salt-from-xtal-1957-CM-3D-balls-horizontal.png|thumb|222px|right|Magnus's green salt is an example of a linear chain compound.]]
In chemistry and materials science, '''linear chain compounds''' are materials composed of one-dimensional arrays of metal-metal bonded molecules or ions. Such materials exhibit anisotropic electrical conductivity.<ref name="Bera">{{cite journal |author1=Bera, J. K. |author2=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><ref name=Miller/>
==Examples== Many linear chain compounds feature square planar complexes. One example is {{chem2|Rh(acac)(CO)2}}, which stack with {{chem2|Rh***Rh}} distances of about 326 pm.<ref name=huq>{{cite journal|title=Refinement of the crystal structure of acetylacetonatodicarbonylrhodium(I)|last1=Huq|first1=Fazlul|last2=Skapski|first2=Andrzej C.|journal=J. Cryst. Mol. Struct.|year=1974|volume=4|issue=6|pages=411–418|doi=10.1007/BF01220097|bibcode=1974JCCry...4..411H |s2cid=96977904}}</ref> Classic examples include Krogmann's salt and Magnus's green salt. Another example is the partially oxidized derivatives of {{chem2|[Pt(oxalate)2](2-)}}. The otherwise ordinary complex {{chem2|IrBr(CO)3}} gives an electrically conductive derivative upon oxidation, e.g., with bromine to give {{chem2|IrBr_{1+''x''}(CO)_{3-''x''} }}, where x ~0.05.<ref name=Miller>{{cite book |doi=10.1007/978-1-4613-3249-7|title=Extended Linear Chain Compounds|last1=Miller|first1=Joel S.|editor1-first=Joel S|editor1-last=Miller|year= 1982|publisher=Springer-Verlag|isbn=978-1-4613-3251-0}}</ref><ref>{{cite journal |doi=10.1016/j.poly.2015.09.050|title=Revisiting Ir(CO)3Cl|year=2016|last1=Tsuji|first1=Yuta|last2=Hoffmann|first2=Roald|last3=Miller|first3=Joel S.|journal=Polyhedron|volume=103|pages=141–149|doi-access=free}}</ref> Related chlorides have the formulae {{chem2|IrCl_{1+''x''}(CO)3}} and {{chem2|K_{0.6}Ir(CO)2Cl2*½H2O}}.<ref>{{cite book |doi=10.1002/9780470132500.ch5|title=Inorganic Syntheses|year=2007|last1=Ginsberg|first1=A. P.|last2=Koepke|first2=J. W.|last3=Sprinkle|first3=C. R.|chapter=Linear-Chain Iridium Carbonyl Halides |pages=18–22|volume=19|isbn=9780470132500}}</ref>
In contrast to linear chain compounds, extended metal atom chains (EMACs) are molecules or ions that consist of a finite, often short, linear strings of metal atoms, surrounded by organic ligands.<ref>F. Albert Cotton, Carlos A. Murillo, Richard A. Walton (eds.), ''Multiple Bonds Between Metal Atoms'', 3rd edition, Springer (2005)</ref>
thumb|360 px|An {{chem2|Ni9}} EMAC.<ref>{{cite journal|doi=10.1039/b923125k|pmid=20372713|title=Probing the electronic communication of linear heptanickel and nonanickel string complexes by utilizing two redox-active [Ni2(napy)4]3+ moieties|year=2010|last1=Hua|first1=Shao-An|last2=Liu|first2=Isiah Po-Chun|last3=Hasanov|first3=Hasan|last4=Huang|first4=Gin-Chen|last5=Ismayilov|first5=Rayyat Huseyn|last6=Chiu|first6=Chien-Lan|last7=Yeh|first7=Chen-Yu|last8=Lee|first8=Gene-Hsiang|last9=Peng|first9=Shie-Ming|journal=Dalton Transactions|volume=39|issue=16|pages=3890–6|url=http://ntur.lib.ntu.edu.tw/bitstream/246246/239455/-1/441.pdf }}</ref>
[[File:ACABRH02.png|thumb|left|Portion of the lattice of Dicarbonyl(acetylacetonato)rhodium(I) ({{chem2|Rh(acac)(CO)2}}) showing the "stacking" of the individual planar units through {{chem2|Rh***Rh}} interactions.]]
One group of platinum chains is based on alternating cations and anions of {{chem2|[Pt(CNR)4](2+)}} (R = ''i''Pr, {{chem2|''c''\-C12H23}}, {{chem2|''p''\-(C2H5)C6H4}}) and {{chem2|[Pt(CN)4](2-)}}.<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 |author1=Grate, J. W. |author2=Moore, L. K. |author3=Janzen, D. E. |author4=Veltkamp, D. J. |author5=Kaganove, S. |author6=Drew, S. M. |author7=Mann, K. R. |journal= Chem. Mater. |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 |author1=Buss, C.E. |author2=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''\-(C2H5)C6H4)2(CN)2, a Crystalline Vapoluminescent Compound That Detects Vapor-Phase Aromatic Hydrocarbons |doi= 10.1021/ja011986v |pmid=11829612 |bibcode=2002JAChS.124.1031B }}</ref><ref name="Buss '98">{{ cite journal |author1=Buss, C.E. |author2=Anderson, C.E. |author3=Pomije, M. K. |author4=Lutz, C. M. |author5=Britton, D. |author6=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''\-C3H7)4][M(CN)4] for M = Pt or Pd |doi= 10.1021/ja981218c |bibcode=1998JAChS.120.7783B }}</ref>
Linear chains of Pd-Pd bonds protected by a "π-electron sheath" are known.<ref name="Bera"/><ref name="Mino">{{ cite journal |first1= Y|last1= Mino|first2= E|last2=Mochizuki|first3= Y|last3=Kai|first4= H|last4=Kurosawa |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>
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 |last1= Murahashi|first1= T|last2= Nagai|first2= Okuno, T|last3= Matsutani|first3= T|last4= Kurosawa|first4= 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>
==Methodology== Some linear chain compounds are produced or fabricated by electrocrystallization. The technique is used to obtain single crystals of low-dimensional electrical conductors.<ref>{{cite book | last1 = Williams | year=1989|first1 = Jack M | title=Inorganic Syntheses| volume = 26 | pages = 386–394 | doi = 10.1002/9780470132579.ch70 | isbn = 978-0-470-13257-9 | chapter = Highly Conducting and Superconducting Synthetic Metals }}</ref>
==See also== *platinum pop
==References== <references /> Category:Nanotechnology Category:Conductive polymers Category:Molecular electronics Category:Semiconductor material types