Osmim And Rythenium Deeksha

ASSIGNMENT CHEMISTRY OF RUTHENIUM AND OSMIUM (GROUP 8 ELEMENT)

GROUP 8 ELEMENTS

Atomic no.

Element

26

Iron (Fe)

44

Ruthenium ( Ru)

76

Osmium (Os)

Electronic configuration [Ar]3d64s2 [Kr]4d75s1 [Xe]4f145d6 6s2

THE ELEMENTS 

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Ruthenium is a chemical element that has the symbol Ru and atomic number 44. Osmium is a chemical element that has the symbol Os and atomic number 76. The chemistry of Ru and Os bears little resemblance to that of Fe . There is an extensive chemistry of M=O species for both the elements.

RUTHENIUM Name, Symbol, Number

Ruthenium, Ru, 44

Element category

transition metals

Group, Period, Block

8, 5, d

Electron configuration

[Kr] 4d7 5s1

Appearance silvery white metallic

Electrons per shell

2, 8, 18, 15, 1

WIKIPEDIA

POSITION IN PERIODIC TABLE

technetium ← Ruthenium →rhodium

•Fe ↑ Ru ↓ Os WIKIPEDIA

OSMIUM Name, Symbol, Number

osmium, Os, 76

Element category

transition metals

Group, Period, Block

8, 6, d

Electron configuration

[Xe] 4f14 5d6 6s2

Appearance silvery white metallic

Electrons per shell

2, 8, 18, 32, 14, 2 WIKIPEDIA

POSITION IN PERIODIC TABLE

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76

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Ru ↑ Os ↓ H WIKIPEDIA

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rhenium ← osmium → iridium

OXIDATION STATES 

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The oxidation states of ruthenium range from +1 to +8, and -2 is known, though oxidation states of +2, +3, and +4 are most common. Although lower oxidation states are known but these are mainly in the π bonding ligands. Cordination numbers vary from 4,5,6,7 and geomerties shown are tetrahedral,tbp,oh,distorted pentagonal bipyramidal respectively.

Oxidation states of osmium Oxidation states of osmium 0

Os(CO)5

+1

OsI

+2

OsI2

+3

OsBr3

+4

OsO2

+5

OsF5

+6

OsF6

+7

OsOF5

+8

OsO4

The complexes of ruthenium and osmium

HALIDES The most important are the chlorides. Ruthenium(III) chloride 

Ruthenium(III) chloride is the chemical compound with the formula RuCl3."Ruthenium(III) chloride" more commonly refers to the hydrate RuCl3·xH2O. 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 use starting material in ruthenium chemistry. PREPRATION RuO4 +HCl

RuCl3.nH2O

Ruthenium(II) chloride They are obtained from in HCl solution which is reduced electrochemically or chemically using ethanol or H2/Pt black.Deep blue air sensitive solution is obtained in a reversible reaction. Ru2(CO2Me)4

Blue solution

(not crystalline) The blue solution made by reduction have been much used as starting material for the synthesis of Cp2Ru ,phosphine complexes,[Ru(bipy)3]2+,[RuCl6],bipyridyl complexes and Ru(acac)3.

Ru(II) Complexes RuCl2(bipy)2,RuCl2(NMe)4 ,they have Cl at the trans position.

Ruthenium(III) chloro complexes These range from [RuCl6]3- to [RuCl(H2O)5]2+ [RuCl6]3- + H2O [RuCl(H2O)5]2+

[RuCl(H2O)]2- + Cl[Ru(H2O6]3+ + Cl-

Complexes like trans [RuCl4L2] where L =imidazole; have antitumor Activity.

Ruthenium(IV) chloro complexes It forms complexes with ligands like OH and water . [RuCl6]2- Ion is formed only in high concentrations of chloride ion by chlorine oxidation of Ru(III) chlorocomplexes.The purple brown salts are isomorphous with other [MCl6] species of Os , Ir , Pd ,Pt.

DINUCLEAR COMPLEXES These are of the type [RuX6]n-;X=Cl,Br;n=1-4;all have octahedral geometry.When n=4,there is a mixed valence,II-III and reduced species have been observed in electrochemical studies.

Fluoroanions [ RuF6]n-;n=1-3 are well established and can be obtained by reactions like RuCl3+MCl+F2 MRuF6 Ru +MCl2 +BrF3

MRuF6

These salts can be reduced by water and oxygen is evolved NITROGEN LIGANDS COMPLEXES Ru complexes with N ligands and the chemistry is very extensive. AMMONIA COMPLEXES The orange hexaammine [Ru(NH3)6]Cl2 is formed when ammonical solution of RuCl3( aq ) containing excess NH4Cl are reduced by Zn. The hexaammine is a reductant [Ru(NH3)6]Cl2 +e = [Ru(NH3)6]2+ ;E0 =0.24 V

Creutz-Taube Complexes 

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The “Creutz-Taube Ion” is the metal complex with the formula [Ru(NH3)5]2(C4H4N2)5+. This cationic species has been heavily studied in an effort to understand the intimate details of inner sphere electron transfer, that is, how electrons move from one metal complex to another. The ion is named after Carol Creutz, who first prepared the complex, and her thesis advisor Henry Taube who received a Nobel Prize in Chemistry for this and related discoveries on electrontransfer.

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There is a series of complexes whose common feature is the presence of two or more Ru atoms bridged by bidentate ligands through which a potentially adustable degree of electron transfer can take place. Such complexes are studied because of the information they give about the general characteristics of electron transmission through chemical systems, including spectroscopic phenomena. Thus ion has mixed valancies,II-III ,II-II,III-III salts have been isolated . This ion provides a model for study of intervalence transfer absorption bands characteristic of trapped valent species that correspond to the process [Ru(II) – Ru(III)] 3+ [Ru(III) – Ru(II)] 2+ This reaction is done in the presence of light.

AROMATIC AMINE COMPLEXES 

Complexes of pyridines,bipyridyls,terpydyls and other polypyridines differ considerably from that of ammonia and aliphatic amines.

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They have been intensively studied because many of them have unusual properties of photo induced energy migrations,luminescence,photocatalytic reactions and water activation. They are also involved in the construction of double helical complexes that bind to DNA and molecular rods and wires for fast electron transfer

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Tris(bipyridine)ruthenium(II) chloride

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Tris(bipyridine)ruthenium( II) dichloride is the chemical compound with the formula [Ru(bipy)3]Cl2. This salt is obtained as the hexahydrate, although all of the properties of interest are in the cation [Ru(bipy)3]2+, which has received much attention because of its distinctive optical properties .

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This orange crystalline salt is prepared by treating aqueous solution of ruthenium trichloride with 2,2'-bipyridine. In this conversion, Ru(III) is reduced to Ru(II), and hypophosphorous acid is typically added as a reducing agent. [Ru(bipy)3]2+ is an octahedral coordination complex. It is used as a sensitizer in photodriven chemical chemical and physical processess such as photolysis of water The bipyridyls of Ru and Os are quite similar and can occur in singly, doubly and triply reduced forms .

OTHER NITROGEN LIGANDS It forms complexes with with nitriles ,porphyrins complexes with ligands like ammonia ,MeSO2 etc; like Ru2(porph)2 that have Ru-Ru bonds. Complexes can be both monomeric and dimeric.

GOOGLE IMAGES

PHOSPHINE COMPLEXES  

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The phosphine complexes are same for both Os and Ru. They can be prepared when RuCl3.nH2O reacts with alcohol in the presence of PR3 Sodiumborohydride can also be used as the reducing agent . RuH2(PPh3)3 are active catalysts for hydrogenation of C=C. Ru complexes of chiral phosphines notably BINAP2,2'-bis(diphenylphosphino)-1,1'-binaphthyl are very useful for industrial hydrogenations and H-transfer hydrogenation of alkene and ketones.

BINAP 

BINAP is an acronym for the organophosphorus compound 2,2'-bis (diphenylphosphino)1,1'-binaphthyl. This chiral ligand is widely used in asymmetric synthesis. BINAP is used in organic synthesis for enantioselective transformations catalyzed by its complexes of ruthenium ,rhodium, and palladium .

GOOGLE IMAGES

Oxygen and sulphur ligands There are many complexes such as [RuEDTA(H2O)]2-. Carboxylates have oxygen and sulfur bonding.carboxylates have Ru=O group. There are relatively few ruthenium complexes of sulfur ligand Ruthenium oxo compounds  RUTHENATES 1) Perruthenates ion ,RuO4- ; RuO4 +( Prn4N) RuO4The salt is soluble in organic solvents.There are vast array of oxoruthenium compounds in oxidation states from III to VII.These may have Ru=O ,µ-o bridge groups (which may be linear or bent) 

Ruthenium oxo compounds 

Ruthenium tetroxide

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It is a volatile ,toxic solid ,mp=25.5 has ozone like odour.It is obtained when aq solution of RuCl3 is oxidized by KIO4 and then RuO4 swept out by a gas stream or extracted into CCl4.

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It is decomposed by light and when pure it explodes above 180 0C,giving RuO2 and O2.

Aqua ions of Ru (II),(III),(IV) There are aqua ions in II,III,IV oxidation states of which the divalent,diamagnetic,pink[Ru(H2O)]2+ is the most important as it is a useful starting material for the synthesis of numerous ruthunium complexes. PREPRATION RuO2 +NaIO4

RuO4

Reduction/Pb

[Ru(H2O)]2+

The lead ions are removed with sulphuric acid and [Ru(H2O)]2+ is isolated as the toluene sulfonate after ion exchange treatment .the tosylate is readily converted to triflate by ion exchange.  The 2+ ion is readily oxidized by air to yellow [Ru(H O)]3+ is 2 for which the reduction potential is 0.23V.  The water in [Ru(H O)]2+ can be readily substituted by 2 chloride ions and other anions and by neutral ligands like DMSO and MeCN.  The +2 aqua ion catalyzes several reactions in solution such as dimerization of ethylene via intermediates [Ru(C2H4)(H2O)5]2+ and [Ru(C2H4)(H2O)5]3+ and that were isolated as tosylates.  It also catalyzes polymerization of norbornenes Ru (IV) ions are Hn[RuO6(H2O)12](4+n)+ 

Ruthenocene

Ruthenocene, C10H10Ru, is an organometallic compound consisting of a ruthenium ion sandwiched in between two cyclopentadiene rings. This structure can be classified as a sandwich compound and more specifically, as a metallocene. GOOGLE IMAGES

OSMIUM COMPLEXES 

Halide complexes

The interaction of the osmate ion with aqueous HCl leads via complex transformations to species in oxidation states III and IV some with Os=O or OH groups .The most common and useful salts for synthesis are those of hexachloroosmate(IV) ion,which are readily obtained by reducing HCl with OsO4 by Fe(II) ,the salts are brownorange. The ion can further be reduced to [OsCl6]3-by .The Os (V) ion is obtained by the reaction OsO4 +SCl2+Cl2 [SCl3]+[OsCl6] Os2Cl10+SCl2 +Cl2

Oxo ,imido and nitrido compounds 

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The higher oxidations of both Ru and Os have a very extensive and important chemistry . The oxo species are widely used as oxidizing agents for organic compounds. Since M=O and M=NR are isoelectronic ,it is convenient to discuss them together and they come under nitrido chemistry.

Osmium oxo compounds 

Osmium tetroxide

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Osmium tetroxide exists as a pale yellowbrown crystalline solid with a odor similar to ozone. OsO4 is volatile: it sublimes at room temperature.mp=400C It is soluble in a wide range of organic solvents, and moderately soluble in water. It is obtained by burning Os with oxygen .

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Os + 2 O2 → OsO4  

It is toxic and hahadrous to eyes. It form coloured but weak complexes with arenes

WIKIPEDIA

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It undergoes cis hydroxylation which involves [3+2] or [2+2] cycloaddition.

ANSWERS.COM

Osmium complexes with nitrogen ligands 

Much of the ammonia complexes resemble that of Ru CH2 en

CH

CH2 Os

en

CH

Compounds with M-M multiple bonds 

Both Ru and Os form many compounds in which the multiply bonded M2n+ cores are bridged by four ligands such as carboxyl anions. CR

CR R’N

O

R’N

O

 Both form dinuclear porphyrin complexes such as M2(Oep)2.

Carbon monoxide derivatives 

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RuCl3(H2O)x reacts with carbon monoxide under mild conditions.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 RuCl3(H2O)x to 1 atm of CO gives, depending on the specific conditions, [Ru2Cl4(CO)4], [Ru2Cl4(CO)4]2-, and [RuCl3(CO)3]-. Addition of ligands (L) to such solutions gives Ru-Cl-CO-L compounds (L = PR3). Reduction of these carbonylated solutions with Zn affords the orange triangular cluster [Ru3(CO)12]. 3 RuCl3·xH2O + 4.5 Zn + 12 CO (high pressure) → Ru3(CO)12 + 3 H2O + 4.5 ZnCl2

Triruthenium dodecarbonyl 

Triruthenium dodecarbonyl is the chemical compound with the formula Ru3(CO)12. This orangecolored metal carbonyl cluster is a precursor to other organo-ruthenium compounds.

GOOGLE IMAGES

Triosmium dodecarbonyl 

Triosmium dodecarbonyl is a chemical compoundwith the formula Os3(CO)12. This yellow colored metal carbonyl cluster is an important precursor to organo-osmium compounds. Many of the advances in cluster chemistry have arisen from studies on derivatives of Os3(CO)12 and its lighter analogue Ru3(CO)12 GGOGLE IMAGES

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