Organoruthenium chemistry is thechemistry oforganometallic compounds containing acarbon torutheniumchemical bond. Several organorutheniumcatalysts are of commercial interest[1] and organoruthenium compounds have been considered for cancer therapy.[2]The chemistry has some stoichiometric similarities withorganoiron chemistry, as iron is directly above ruthenium ingroup 8 of the periodic table. The most important reagents for the introduction of ruthenium areruthenium(III) chloride andtriruthenium dodecacarbonyl.
In its organometallic compounds, ruthenium is known to adopt oxidation states from −2 ([Ru(CO)4]2−) to +6 ([RuN(Me)4]−). Most common are those in the +2 oxidation state, as illustrated below.
bis(triphenylphosphine)ruthenium.png)
As with other late transition metals, ruthenium binds more favorably withsoft ligands.[3] The most importantligands for ruthenium are:
While monodentate phosphine ligands such astriphenylphosphine andtricyclohexylphosphine are most common, bidentate phosphine ligands can also be useful in organoruthenium compounds.BINAP, in particular, is a usefulasymmetric ligand for many asymmetric ruthenium catalysts.[4][5][6][7]
NHC ligands have become very common in organoruthenium complexes.[8][9] NHC ligands can be prepared with precise steric and electronic parameters, and can be chiral for use in asymmetric catalysis.[10] NHCs, as strongly donatingL-type ligands, are often used to replace phosphine ligands. A notable example is 2nd generationGrubbs catalyst, in which a phosphine of the 1st generation catalyst is replaced by an NHC.
The parent compoundruthenocene is unreactive because it is coordinatively saturated and contains no reactive groups.Shvo catalyst ([Ph4(η5-C4CO)]2H]}Ru2(CO)4(μ-H)) is also coordinatively saturated, but features reactive OH and RuH groups that enable it to function intransfer hydrogenation.[11] It is used inhydrogenation ofaldehydes,ketones, viatransfer hydrogenation, indisproportionation ofaldehydes toesters and in the isomerization of allylic alcohols.
Chloro(cyclopentadienyl)bis(triphenylphosphine)ruthenium features a reactive chloro group, which is readily substituted by organic substrates.
One example of an Ru-arene complex is(cymene)ruthenium dichloride dimer, which is the precursor to a versatile catalyst fortransfer hydrogenation.[12]Acenaphthylene forms a useful catalyst derived fromtriruthenium dodecacarbonyl.[13] Thehapticity of thehexamethylbenzene ligand in Ru(C6Me6)2 depends on the oxidation state of the metal centre:[14] The compound Ru(COD)(COT) is capable ofdimerizingnorbornadiene:
Multinuclear organo-ruthenium complexes have been investigated for anti-cancer properties. The compounds studied include di-, tri-, and tetra-nuclear complexes and tetrara-, hexa-, and octa- metalla-cages.[2]
The main ruthenium carbonyl istriruthenium dodecacarbonyl, Ru3(CO)12. The analogues of the popular reagents Fe(CO)5 and Fe2(CO)9 are not very useful.Ruthenium pentacarbonyl decarbonylates readily:
Carbonylation of ruthenium trichloride gives a series of Ru(II) chlorocarbonyls. These are the precursors to Ru3(CO)12.
Compounds ofcarbon with other elements in the periodic table | |
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