Ruthenium , carbonyl complexes with

Ghosh P, Fagan PJ, Marshall WJ, Hauptman E, Bullock RM (2009) Synthesis of ruthenium carbonyl complexes with phosphine or substituted Cp ligands, and their activity in the catalytic deoxygenation of 1,2-propanediol. Inorg Chem 48 6490-6500... 

Allylation of perfluoroalkyl halides with allylsilanes is catalyzed by iron or ruthenium carbonyl complexes [77S] (equation 119) Alkenyl-, allyl-, and alkynyl-stannanes react with perfluoroalkyl iodides 111 the presence ot a palladium complex to give alkenes and alkynes bearing perfluoroalkyl groups [139] (equation 120)... 

This system shows an induction period of about six hours before constant activity is attained during which the Ru3(C0)12 undergoes complete conversion to another ruthenium carbonyl complex. In situ nmr studies suggest this species to be the HRu2(C0)e ion. Kinetic studies show complex rate profiles however, a key observation is that the catalysis rate is first order in Pco at low pressures (Pcohigher pressures. A catalysis scheme consistent with these observations is proposed. 

Subsequent insertion of CO into the newly formed alkyl-ruthenium moiety, C, to form Ru-acyl, D, is in agreement with our 13C tracer studies (e.g., Table III, eq. 3), while reductive elimination of propionyl iodide from D, accompanied by immediate hydrolysis of the acyl iodide (3,14) to propionic acid product, would complete the catalytic cycle and regenerate the original ruthenium carbonyl complex. 

Although this spectrum does not correspond to any particular ruthenium carbonyl complex, it is consistent with the presence of one or more anionic ruthenium carbonyl complexes, perhaps along with neutral species. Work is in progress with a variable path-length, high pressure infrared cell designed by Prof. A. King, to provide better characterization of species actually present under reaction conditions. 

Solutions of ruthenium carbonyl complexes in acetic acid solvent under 340 atm of 1 1 H2/CO are stable at temperatures up to about 265°C (166). Reactions at higher temperatures can lead to the precipitation of ruthenium metal and the formation of hydrocarbon products. Bradley has found that soluble ruthenium carbonyl complexes are unstable toward metallization at 271°C under 272 atm of 3 2 H2/CO [109 atm CO partial pressure (165)]. Solutions under these conditions form both methanol and alkanes, products of homogeneous and heterogeneous catalysis, respectively. Reactions followed with time exhibited an increasing rate of alkane formation corresponding to the decreasing concentration of soluble ruthenium and methanol formation rate. Nevertheless, solutions at temperatures as high as 290°C appear to be stable under 1300 atm of 3 2 H2/CO. 

Another possible reason that ethylene glycol is not produced by this system could be that the hydroxymethyl complex of (51) and (52) may undergo preferential reductive elimination to methanol, (52), rather than CO insertion, (51). However, CO insertion appears to take place in the formation of methyl formate, (53), where a similar insertion-reductive elimination branch appears to be involved. Insertion of CO should be much more favorable for the hydroxymethyl complex than for the methoxy complex (67, 83). Further, ruthenium carbonyl complexes are known to hydro-formylate olefins under conditions similar to those used in these CO hydrogenation reactions (183, 184). Based on the studies of equilibrium (46) previously described, a mononuclear catalyst and ruthenium hydride alkyl intermediate analogous to the hydroxymethyl complex of (51) seem probable. In such reactions, hydroformylation is achieved by CO insertion, and olefin hydrogenation is the result of competitive reductive elimination. The results reported for these reactions show that olefin hydroformylation predominates over hydrogenation, indicating that the CO insertion process of (51) should be quite competitive with the reductive elimination reaction of (52). 

The results show that a number of ruthenium carbonyl complexes are effective for the catalytic carbonylation of secondary cyclic amines at mild conditions. Exclusive formation of N-formylamines occurs, and no isocyanates or coupling products such as ureas or oxamides have been detected. Noncyclic secondary and primary amines and pyridine (a tertiary amine) are not effectively carbonylated. There appears to be a general increase in the reactivity of the amines with increasing basicity (20) pyrrolidine (pKa at 25°C = 11.27 > piperidine (11.12) > hexa-methyleneimine (11.07) > morpholine (8.39). Brackman (13) has stressed the importance of high basicity and the stereochemistry of the amines showing high reactivity in copper-catalyzed systems. The latter factor manifests itself in the reluctance of the amines to occupy more than two coordination sites on the cupric ion. In some of the hydridocar-bonyl systems, low activity must also result in part from the low catalyst solubility (Table I). 

It is also relevant to record that several iron-carbonyl complexes with bridging, and in one case terminal, aryltellurol ligands have been prepared by reaction of Fe(CO)5, Fe(CO)12 or [ji-CpFe(CO)2]2 with diaryl ditellurides and which, together with complexes containing other transition metal carbonyls, e.g, ruthenium, osmium and manganese, provide a substantial number of interesting compounds.2... 

Ruthenium carbonyl complexes, for example, Ru3(CO) 12 can be used as catalysts for the synthesis of oligosilazanes via dehydrocoupling of Si-H bonds with H-N bonds (Eq. 117) [185]. 

Treatment of the disubstituted vinylidene complex 124 with base in wet methanol cleaves the vinylidene bond to give the cationic ruthenium carbonyl complex 126 and bibenzyl in good yield. This reaction presumably proceeds via initial formation of the acyl complex 125, which decomposes to give the products [Eq. (106)] (78). Other mono- and disubstituted vinylidene complexes, however, do not give identifiable decomplexation... 

Experiments with cyclooctatetraene and its methyl and phenyl derivatives have demonstrated that reaction with certain ruthenium carbonyl complexes can occur with transannular bonding to give pentalene complexes directly.253,264 The structures of these unique molecules have been confirmed by X-ray crystallography. 

Mono- and Dinuclear Compounds. The pentacarbonyl is a starting material for mononuclear ruthenium carbonyl complexes. As outlined in Scheme 3, reduction with sodium in liquid ammonia yields a pale-colored anion solution (5),... 

Recent literature describes the synthesis of vinyl esters in the presence of platinum metal complexes. Complexes which have proven particularly suitable in this context are those of ruthenium (eq. (15)), such as, for example, cyclooc-tadienylruthenium halides [36], ruthenium carbonyl complexes, and ruthenium acetate complexes [37]. A characteristic feature of these is their high selectivity with regard to acetylene, so that the production of acetylene polymers is reduced. 

Watanabe et al. reported that the addition of C-H bonds in aldehydes to olefins took place efficiently with the aid of Ru3(CO)12 under a CO atmosphere at 200°C (Eq. 51) [118]. They also reported that the same ruthenium-carbonyl complex catalyzes the addition of the C-H bonds in formic acid esters and amides to olefins (Eq. 52) [119]. 

Ruthenium carbonyl complex undergoes successive oxidative addition of Si-Si bond of 1 to give tetrakis(organosilyl)(CO)3Ru(IV) complex 30 as a major,kinetic product, which further reacts with the Ru3(CO)12 to give bis(silyl)Ru(II) complex 31 (Eq. 13) [28],... 

In this section, we will review the nature and chemical reactivities of several kinds of ruthenium complexes under the following headings ruthenium carbonyl complexes, dichlororuthenium complexes, chlorohydrido complexes, dihydridoruthenium complexes, ruthenium complexes with chiral ligands, ruthenium complexes with cyclopentadienyl ligands, and ruthenium arene/diene complexes. 

Cyclooctatetraene (COT) iron carbonyl complexes and ruthenium carbonyl complexes (Table 5) have raised a good deal of interest as flux-ional molecules which display temperature dependent NMR spectra e.g. COT-Fe(CO)3 shows only one sharp peak at room temperature, but a pattern conceivable with... 

Hydroxycarbonylation of olefins (Scheme 5.11) in fully aqueous solution was studied using a ruthenium-carbonyl catalyst with no phosphine ligands [35]. In a fine mechanistic study it was shown, that (the WGS) reaction of /ac-[Ru(C0)3(H20)3]2+ and water provided /ac-[RuH(CO)2(H20)3]+. At 70 °C and in the presence of CF3S03H the latter compound reacted with ethene (10 bar) giving a a-alkylruthenium complex, solutions of which absorbed CO and yielded the corresponding acyl-derivative ... 

Although C-S bond cleavage reactions between thiophenes and osmium clusters have not been observed, selenophene and tellurophene undergo ring opening reactions with [Os3(CO)io(NCMe)2] to give complexes 28a and 28b (Scheme T). " It is likely that the sulfur-extrusion reactions of iron and ruthenium carbonyl clusters with thiophenes proceed via ring-opened intermediates of this type. 

The reactions of iron carbonyls with diorgano tellurides deserve mention, for example the reaction of Fe3(CO),2 with PhjTe gives Ph2TeFe(CO>4, whilst several ruthenium-carbonyl complexes have been prepared from reactions between diphenyl telluride and alcoholic carbon monoxide-saturated solutions of ruthenium trichloride hydrate. Various other ruthenium-carbonyl complexes of diorgano teUurides, including di- and tri-substituted species, have also been described. The utility of diphenyl telluride in transition metal carbonyl chemistry has also been well illustrated during studies of manganese and rhenium compounds. 

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