Interplay of Cubic Building Blocks in (η6-arene)Ruthenium-Containing Tungsten and Molybdenum Oxides

Abstract

A series of molybdenum and tungsten organometallic oxides containing [Ru(arene)]2+ units (arene =p-cymene, C6Me6) was obtained by condensation of [[Ru(arene)Cl2]2] with oxomolybdates and oxotungstates in aqueous or nonaqueous solvents. The crystal structures of [[Ru(eta6-C6Me6]]4W4O16], [[Ru(eta6-p-MeC6H4iPr]]4W2O10], [[[Ru-(eta6-p-MeC6H4iPr)]2(mu-OH)3]2][[Ru(eta6-p-MeC6H4iPr)]2W8O28(OH)2[Ru(eta6-p-MeC6H4iPr)(H2O)]2], and [[Ru(eta6-C6Me6)]2M5O18[Ru(eta6-C6Me6)(H2O)]] (M = Mo, W) have been determined. While the windmill-type clusters [[Ru(eta6-arene)]4(MO3)4(mu3-O)4] (M = Mo, W; arene =p-MeC6H4iPr, C6Me6), the face-sharing double cubane-type cluster [[Ru(eta6-p-MeC6H4iPr)]4(WO2)2(mu3-O)4(mu4-O)2], and the dimeric cluster [[Ru(eta6-p-MeC6H4iPr)(WO3)3(mu3-O)3(mu3-OH)Ru(eta6-pMeC6H4iPr)(H2O)]2(mu-WO2)2]2- are based on cubane-like units, [(Ru(eta6-C6Me6)]2M5O18[Ru(eta6-C6Me6)(H2O)]] (M = Mo, W) are more properly described as lacunary Lindqvist-type polyoxoanions supporting three ruthenium centers. Precubane clusters [[Ru(eta6-arene)](MO3)2(mu-O)3(mu3-O)]6- are possible intermediates in the formation of these clusters. The cluster structures are retained in solution, except for [[Ru(eta6-p-MeC6H4iPr)]4Mo4O16], which isomerizes to the triple-cubane form.

Adamantane Selective Hydroxylation by 2,6-Dichloropyridine N-Oxide and Organoruthenium(II) Polyoxometalates as Catalyst Precursors

“…[10] We now present preliminary results obtained in the oxyfunctionalisation of adamantane with 2,6-dichloropyridine N-oxide and organoruthenium(II) polyoxometalates with general formula [{Ru(C 6 Me 6 )} 3 M 5 O 18 ], M Mo, W. These complexes are lacunary Lindqvisttype polyoxoanions supporting three ruthenium centres ( Figure 1). [9] [8] In our study, to prevent the incursion of radical oxidation pathways, likely occurring when peroxidic oxidants are used with transition metal catalysts, a heteroaromatic N-oxide was chosen as oxygen donor. [1,11] Furthermore, 2,6-dichloropyridine N-oxide is simply generated by reaction of the parent pyridine with hydrogen peroxide in acidic media, thus a global catalytic process may be envisaged where the pyridine by-product is recycled and the primary oxidant is ultimately H 2 O 2 .…”

“…[7] With this aim, two different routes have been pursued: (i) ruthenium incorporation within the polyoxoanion framework, leading to ruthenium-substituted polyoxometalates; [8] (ii) functionalisation of the polyoxoanion surface leading to ruthenium-supported polyoxometalates. [9] The latter approach has been used for the synthesis of new organometallic species providing the ruthenium centre with a hybrid set of ligands comprising both organic residues and polyoxometalates. [10] We now present preliminary results obtained in the oxyfunctionalisation of adamantane with 2,6-dichloropyridine N-oxide and organoruthenium(II) polyoxometalates with general formula [{Ru(C 6 Me 6 )} 3 M 5 O 18 ], M Mo, W. These complexes are lacunary Lindqvisttype polyoxoanions supporting three ruthenium centres (Figure 1).…”

“…[10] We now present preliminary results obtained in the oxyfunctionalisation of adamantane with 2,6-dichloropyridine N-oxide and organoruthenium(II) polyoxometalates with general formula [{Ru(C 6 Me 6 )} 3 M 5 O 18 ], M Mo, W. These complexes are lacunary Lindqvisttype polyoxoanions supporting three ruthenium centres (Figure 1). [9] Figure 1.…”

High oxidation state organomolybdenum and organotungsten chemistry in protic environments

“…More recently, compounds [(( 6 -arene)Ru) 4 (WO) 4 (-O) 12 ] (arene = C 6 Me 6 , pMeC 6 H 4 iPr) where obtained similarly from Na 2 WO 4 and [( 6 -arene)RuCl 2 ] 2 , although the reaction was conducted in acetonitrile [171]. Compound [(( 6 -arene)Ru) 4 (WO 2 ) 2 (-O) 6 ] was also obtained as a by-product.…”

Sulfur-containing trinuclear arene ruthenium clusters

“…The versatility of arene ruthenium units for cluster build-up reactions is well documented [1][2][3][4][5][6][7][8][9][10][11][12][13][14]. Arene ruthenium clusters have an interesting catalytic potential for hydrogenation reactions and for other processes, in particular hydrodesulfurisation reactions that have been extensively studied in recent years, because of the necessity of removing sulfur from petroleum feedstocks [15].…”