ASSIGNMENT CHEMISTRY OF RUTHENIUM AND OSMIUM (GROUP 8 ELEMENT)
Nov 15, 2014
ASSIGNMENT
CHEMISTRY OF RUTHENIUM AND OSMIUM (GROUP 8 ELEMENT)
GROUP 8 ELEMENTS
Atomic no. Element Electronic configuration
26 Iron (Fe) [Ar]3d64s2
44 Ruthenium ( Ru)
[Kr]4d75s1
76 Osmium (Os) [Xe]4f145d6 6s2
THE ELEMENTS
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
76 rhenium ← osmium → iridium
Ru ↑Os↓H
WIKIPEDIA
OXIDATION STATES
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 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 statesof 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
HALIDESThe most important are the chlorides. Ruthenium(III) chloride
Ruthenium(III) chloride is the chemical compoundwith 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,oftenapproximating 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)]2- + Cl-
[RuCl(H2O)5]2+ [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 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 electron-transfer.
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.
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
Tris(bipyridine)ruthenium(II) chloride
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 .
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
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 BINAP- 2,2'-
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) RuO4
-
The 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 ,-o bridge groups (which may be linear or bent)
Ruthenium oxo compounds
Ruthenium tetroxide 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.
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 [Ru(H2O)]2+
Reduction/Pb
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(H2O)]3+ is for which the reduction potential is 0.23V.
The water in [Ru(H2O)]2+ can be readily substituted by 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 complexesThe 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 brown-orange.
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
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 Osmium tetroxide exists as a pale yellow-
brown 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 .
Os + 2 O2 → OsO4
It is toxic and hahadrous to eyes. It form coloured but weak complexes with
arenes
WIKIPEDIA
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
Os
CH2 CH2
CH CH
en en
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.
CRCR
R’NR’N O
O
Both form dinuclear porphyrin complexes such as M2(Oep)2.
Carbon monoxide derivatives 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 orange-colored 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
THANKS