Ruthenium(III) chloride 2701007 215343835 2008-05-27T20:01:57Z DOI bot 6652755 Citation maintenance. You can [[WP:DOI|use this bot]] yourself! Please [[User:DOI_bot/bugs|report any bugs]]. {{Chembox new | Name = Ruthenium(III) chloride<!-- please replace if not identical with the pagename --><!-- | align="center" |<!-- replace if not identical with the pagename --> |- | [[IUPAC name|Systematic name]] | Ruthenium trichloride<br />Ruthenium(III) chloride |- --> | Section1 = {{Chembox Identifiers | CASOther = 10049-08-8 (anhydrous)<br />14898-67-0 (hydrate)<br />13815-94-6 (trihydrate) }} | Section2 = {{Chembox Properties | Formula = RuCl<sub>3</sub>·''x''H<sub>2</sub>O | MolarMass = 207.43 g/mol (anhydrous)<br />261.47 g/mol (trihydrate) | Solvent = other solvents | SolubleOther = Soluble | MeltingPt = >500 °C (decomp.) }} | Section3 = {{Chembox Structure | Coordination = octahedral | CrystalStruct = [[Chromium(III) chloride|CrCl<sub>3</sub>]] }} | Section7 = {{Chembox Hazards | ExternalMSDS = | MainHazards = probably toxic | RPhrases = 34 | SPhrases = 26-27-36/37/39 }}<!-- | [[RTECS number]] | VM2650000 |- --> | Section8 = {{Chembox Related | OtherAnions = RuBr<sub>3</sub>(H<sub>2</sub>O)<sub>x</sub> | OtherCations = [[Rhodium(III) chloride|RhCl<sub>3</sub>]]<br />[[Iron(III) chloride|FeCl<sub>3</sub>]]<br /> | OtherCpds = [[Ruthenium tetroxide|RuO<sub>4</sub>]]<br /> }} }} '''Ruthenium(III) chloride''' is the [[chemical compound]] with the formula RuCl<sub>3</sub>. "Ruthenium(III) chloride" more commonly refers to the hydrate RuCl<sub>3</sub>·''x''H<sub>2</sub>O. Both the anhydrous and hydrated species are dark brown or black solids. The hydrate, with a varying proportion of [[water of crystallization]], often approximating to a trihydrate, is a commonly used starting material in [[ruthenium]] chemistry. ==Preparation and properties== The anhydrous forms of ruthenium(III) chloride are well characterized but rarely used. Crystalline material is usually prepared by heating powdered ruthenium metal to 700 °C under a 4:1 mixture of [[chlorine]] and [[carbon monoxide]]: the product is carried by the gas stream and crystallises upon cooling.{{ref|Remy}} RuCl<sub>3</sub> exists is two crystalline modifications. The black α-form adopts the [[Chromium(III) chloride#structure|CrCl<sub>3</sub>-type]] structure with long Ru-Ru contacts of 346 [[picometre|pm]]. The dark brown [[metastable]] β-form crystallizes in a hexagonal cell; this form consists of infinite chains of face-sharing octahedra with Ru-Ru contacts of 283 pm. The β-form is irreversibly converted to the α-form at 450&ndash;600 °C. RuCl<sub>3</sub> vapour decomposes into the [[Chemical element|elements]] at high temperatures (as do all compounds!): the [[Enthalpy|enthalpy change]] at 750 °C (1020 K), Δ<sub>diss</sub>''H''<sub>1020</sub> has been estimated as +240&nbsp;kJ/mol. ==Coordination chemistry== As the most commonly available ruthenium compound, RuCl<sub>3</sub>·''x''H<sub>2</sub>O is the precursor to many hundreds of chemical compounds. The noteworthy property of ruthenium complexes, chlorides and otherwise, is the existence of more than one oxidation state, several of are kinetically inert. All second and third-row transition metals form exclusively low spin complexes, whereas ruthenium is special in the stability of adjacent oxidation states, especially Ru(II), Ru(III) (as in the parent RuCl<sub>3</sub>·''x''H<sub>2</sub>O) and Ru(IV). ===Illustrative complexes derived from "ruthenium trichloride"=== *RuCl<sub>2</sub>([[triphenylphosphine|PPh<sub>3</sub>]])<sub>3</sub>, a chocolate-colored, benzene-soluble species, which in turn is also a versatile starting material. It arises approximately as follows: :2RuCl<sub>3</sub>·''x''H<sub>2</sub>O + 7 PPh<sub>3</sub> → 2 RuCl<sub>2</sub>(PPh<sub>3</sub>)<sub>3</sub> + OPPh<sub>3</sub> + 5 H<sub>2</sub>O + 2 HCl *[RuCl<sub>2</sub>([[benzene|C<sub>6</sub>H<sub>6</sub>]])]<sub>2</sub>, also chocolate brown, poorly soluble complex of benzene, arising from [[1,3-cyclohexadiene]] as follows: :2 RuCl<sub>3</sub>·''x''H<sub>2</sub>O + 2 C<sub>6</sub>H<sub>8</sub> → [RuCl<sub>2</sub>(C<sub>6</sub>H<sub>6</sub>)]<sub>2</sub> + 6 H<sub>2</sub>O + 2 HCl + H<sub>2</sub> The benzene ligand can be exchanged with other arenes such as hexamethylbenzene. *[[Ruthenium tris(bipyridine) chloride|Ru(bipy)<sub>3</sub>Cl<sub>2</sub>]], an intensely luminescent salt with a long-lived excited state, arising as follows: :RuCl<sub>3</sub>·''x''H<sub>2</sub>O + 3 [[2,2'-bipyridine|bipy]] + 0.5 CH<sub>3</sub>CH<sub>2</sub>OH → [Ru(bipy)<sub>3</sub>]Cl<sub>2</sub> + 3 H<sub>2</sub>O + 0.5 CH<sub>3</sub>CHO + HCl This reaction proceeds via the versatile intermediate cis-Ru(bipy)<sub>2</sub>Cl<sub>2</sub>. *[RuCl<sub>2</sub>([[Cp*|C<sub>5</sub>Me<sub>5</sub>)]]]<sub>2</sub>, arising as follows: :2 RuCl<sub>3</sub>·''x''H<sub>2</sub>O + 2 C<sub>5</sub>Me<sub>5</sub>H → [RuCl<sub>2</sub>(C<sub>5</sub>Me<sub>5</sub>)]<sub>2</sub> + 6 H<sub>2</sub>O + 2 HCl [RuCl<sub>2</sub>(C<sub>5</sub>Me<sub>5</sub>)]<sub>2</sub> can be further reduced to [RuCl(C<sub>5</sub>Me<sub>5</sub>)]<sub>4</sub>. *Ru([[acetylacetonate|C<sub>5</sub>H<sub>7</sub>O<sub>2</sub>]])<sub>3</sub>, a red, benzene-soluble coordination complex arising as follows: :RuCl<sub>3</sub>·''x''H<sub>2</sub>O + 3 C<sub>5</sub>H<sub>8</sub>O<sub>2</sub> → Ru(C<sub>5</sub>H<sub>7</sub>O<sub>2</sub>)<sub>3</sub> + 3 H<sub>2</sub>O + 3 HCl *[[Ruthenium tetroxide|RuO<sub>4</sub>]], an orange CCl<sub>4</sub>-soluble oxidant with a tetrahedral structure, which is of some interest in [[organic synthesis]]. Several of these compounds were key to two recent [[Nobel Prize]]s. [[Noyori]] was awarded the Nobel Prize in Chemistry in 2001 for the development of practical [[Noyori asymmetric hydrogenation| asymmetric hydrogenation]] catalysts based on ruthenium. [[Grubbs]] was awarded the Nobel Prize in Chemistry in 2005 for the development of practical [[alkene metathesis]] catalysts based on ruthenium [[alkylidene]] derivatives. ===Carbon monoxide derivatives=== RuCl<sub>3</sub>(H<sub>2</sub>O)<sub>x</sub> reacts with carbon monoxide under mild conditions.<ref>*Hill, A. F. ""Simple" Ruthenium Carbonyls of Ruthenium: New Avenues from the Hieber Base Reaction", Angewandte Chemie International Edition, 2000, volume 39, pages 130-134.</ref> In contrast, iron chlorides do not react with CO. CO reduces the red-brown trichloride to yellowish Ru(II) species. Specifically, exposure of an [[ethanol]] solution of RuCl<sub>3</sub>(H<sub>2</sub>O)<sub>x</sub> to 1 atm of CO gives, depending on the specific conditions, [Ru<sub>2</sub>Cl<sub>4</sub>(CO)<sub>4</sub>], [Ru<sub>2</sub>Cl<sub>4</sub>(CO)<sub>4</sub>]<sup>2-</sup>, and [RuCl<sub>3</sub>(CO)<sub>3</sub>]<sup>-</sup>. Addition of ligands (L) to such solutions gives Ru-Cl-CO-L compounds (L = PR<sub>3</sub>). Reduction of these carbonylated solutions with Zn affords the orange triangular cluster [Ru<sub>3</sub>(CO)<sub>12</sub>]. ::3 RuCl<sub>3</sub>·''x''H<sub>2</sub>O + 4.5 Zn + 12 CO (high pressure) → [[Triruthenium dodecacarbonyl|Ru<sub>3</sub>(CO)<sub>12</sub>]] + 3 H<sub>2</sub>O + 4.5 Zn</sub>Cl<sub>2</sub> ==Sources== *''Gmelins Handbuch der Anorganischen Chemie'' ==References== {{Citationstyle|date=September 2007}} {{reflist}} #{{note|Remy}} {{cite journal | author = Remy, H.; Kühn, M. | title = Beiträge zur Chemie der Platinmetalle. V. Thermischer Abbau des Ruthentrichlorids und des Ruthendioxyds | year = 1924 | journal = Z. Anorg. Chem. | volume = 137 | issue = 1 | pages = 365–388 | doi = 10.1002/zaac.19241370127}} *Bennett, M. A.; Huang, T. N.; Matheson, T. W. and Smith, A. K., "(η<sup>6</sup>-Hexamethylbenzene)ruthenium Complexes", Inorganic Syntheses, 1982, volume 21, 74-8. *Ikariya, T.; Murata, K.; Noyori, R. "Bifunctional Transition Metal-Based Molecular Catalysts for Asymmetric Syntheses" Organic Biomolecular Chemistry, 2006, volume 4, 393–406. ==Further reading== *Carlsen, P. H. J. ''et al.'' (1981). ''[[J. Org. Chem.]]'' '''46''':3936. (catalyst for oxidation reactions) *Gore, E. S. (1983). ''Platinum Met. Rev.'' '''27''':111. (review) *Cotton, S. A. "Chemistry of Precious Metals," Chapman and Hall (London): 1997. ISBN 0-7514-0413-6 [[Category:Ruthenium compounds]] [[Category:Chlorides]] [[Category:Metal halides]] [[Category:Coordination compounds]] [[ca:Template:Chembox]] [[es:Plantilla:Chembox]] [[fr:Modèle:Chimiebox général]]