Search

The reaction of the benzothiazolate-capped triosmium clusters Os 3 (CO) 9 (μ 3 ,η 2 -C 7 H 3 NSR)(μ-H) ( 1a , R = H; 1b , R = Me) with PPh 3 proceeds readily at room temperature with a μ 3 ,η 2 → μ,η 2 hapticity change in the benzothiazolate heterocycle to furnish Os 3 (CO) 9 (PPh 3 )(μ,η 2 -C 7 H 3 NSR)(μ-H) ( 2a , R = H; 2b , R = Me) in high yields. X-ray crystallography has confirmed the regiospecific nature of this reaction where the PPh 3 ligand is bound to the osmium atom that serves as the coordination site for the hydride and the metalated-carbon atom associated with the edge-bridged benzothiazolate ligand. The thermolysis of 2a and 2b in boiling toluene affords several new Os 3 clusters as a result of ligand isomerization, decarbonylation, and ortho metalation of the ancillary PPh 3 ligand. The new products have been isolated and characterized by a combination of spectroscopic methods and X-ray crystallography in the case of 3b , 4b , 5b and 6b . Clusters 3b and 4b are isomers of 2b and differ in the location of the hydride and PPh 3 ligands relative to the benzothiazolate moiety. Electronic structure calculations on the isomeric clusters 2b , 3b , and 4b confirm that 2b is the kinetic product of ligand substitution, accounting for its rearrangement to the latter two isomers upon heating. Cluster 5b contains a face-capping benzothiazolate moiety and is shown by DFT calculations to derive from a site-selective loss of an axial CO group in 4b . Cluster 6a,b formed from 5a,b as a result of further decarbonylation with concomitant ortho metalation of one of the phenyl groups of the coordinated PPh 3 ligand. [ABSTRACT FROM AUTHOR]

Reactions of Ru3(CO)10(µ-dppf) (1) (dppf = 1,1'-bis(diphenylphosphino)ferrocene), Ru3(CO)10(µ-dppm) (2) (dppm = bis(diphenylphosphino)methane), and the orthometalated derivative Ru3(CO)9{µ3- PPhCH2PPh(C6H4)} (3) with silanes (Ph3SiH, Et3SiH, Ph2SiH2) are reported. Treatment of 1 with Ph3SiH and Ph2SiH2 at room temperature leads to facile Si--H bond activation to afford Ru3(CO)9(µ-dppf)(SiPh3)(µ-H) (4) (60% yield) and Ru3(CO)9(µ-dppf)(SiPh2H)(µ-H) (6) (53% yield), respectively. The reaction of 1 with Ph3SiH has been investigated by electronic structure calculations, and these data have facilitated the analysis of the potential energy surface leading to 4. Compound 1 does not react with Et3SiH at room temperature but reacts at 68 °C to give Ru3(CO)9(µ-dppf)(SiEt3)(µ-H) (5) in 45% yield. Reaction of 2 with Ph3SiH at room temperature yields two new products: Ru3(CO)9(µ-dppm)(SiPh3)(µ-H) (7) in 40% yield and Ru3(CO)6(µ3-O)(µ-dppm)(SiPh3)(µ- H)3 (8) in 15% yield. Interestingly, at room temperature compound 7 slowly reverts back to 2 in solution with decomposition and liberation of Ph3SiH. Complex 8 can also be prepared from the direct reaction between 7 and H2O. Similar reactions of 2 with Et3SiH and Ph2SiH2 give only intractable materials. The orthometalated compound 3 does not react with Ph3SiH, Et3SiH and Ph2SiH2 at room temperature but does react at 66 °C to give Ru3(µ-CO)(CO)7{µ3- PPhCH2PPh(C6H4)}(SiR2R¹)(µ- H)](9, R = R' = Ph, 71% yield; 10, R = R' = Et, 60% yield; 11, R = Ph, R' = H, 66% yield) by activation of the Si--H bond. Compounds 4 and 8--11 have been structurally characterized. In 4, both the dppf and the hydride bridge a common Ru--Ru vector, whereas NMR studies on 7 indicate that two ligands span different Ru--Ru edges. Compound 8 contains a face-capping oxo moiety, a terminally coordinated SiPh3 ligand, and three bridging hydride ligands, whereas 9--11 represent simple oxidative addition products. In all of the compounds examined, the triruthenium framework retains its integrity and the silyl groups occupy equatorial sites. [ABSTRACT FROM AUTHOR]

Abstract: Upon mild heating (60–65°C), electron-deficient [Os3(CO)9(μ3-C7H4NS)(μ-H)] (1) readily adds to the activated alkyne, RChsp sp="0.25" />=CO2Me), to give two isomers of the alkenyl complexes, [Os3(CO)9(μ-C7H4NS)(μ3-RCCHR)] (2 and 3), differing in the orientation of the benzothiazole ligand. In both the alkenyl ligand acts as a five-electron donor binding through both carbons and one of the oxygen atoms of the substituents, which adopt a relative cis disposition. Heating 2 cleanly affords 3 suggesting that the former is the kinetic product and the latter is thermodynamically favoured. At higher temperatures (110°C), 3 rearranges to a third isomer [Os3(CO)9(μ-C7H4NS)(μ-RCCHR)] (4) which differs in the binding mode of the alkenyl ligand and where the alkyne substituents are in a relative trans disposition. A second product of this reaction is [Os3(CO)8(μ-OCH3){μ3-C7H4NSC(R)C}(μ-H)] (5) which results from the loss of two moles of CO, carbon–carbon coupling between hydrocarbyl and benzothiazole ligands and carbon–hydrogen addition to the triosmium centre. All new clusters are characterized by a total of 50 valence electrons and contain two metal–metal bonds as shown by single crystal X-ray diffraction studies. [Copyright &y& Elsevier]

Abstract: Treatment of unsaturated [Os3(CO)8{μ3-Ph2PCH2P(Ph)C6H4}(μ-H)] (2) with t BuNC at room temperature gives [Os3(CO)8(CNBu t )){μ3-Ph2PCH2P(Ph)C6H4}(μ-H)] (3) which on thermolysis in refluxing toluene furnishes [Os3(CO)7(CNBu t ){μ3-Ph2PCHP(Ph)C6H4}(μ-H)2] (4). Reaction of the labile complex [Os3(CO)9(μ-dppm)(NCMe)] (5) with t BuNC at room temperature affords the substitution product [Os3(CO)9(μ-dppm)(CNBu t )] (6). Thermolysis of 6 in refluxing toluene gives 4. On the other hand, the reaction of unsaturated [Os3(CO)9{μ3-η2-C7H3(2-Me)NS}(μ-H)] (7) with t BuNC yields the addition product [Os3(CO)9(CNBu t ){μ-η2-C7H3(2-Me)NS}(μ-H)] (8) which on decarbonylation in refluxing toluene gives unsaturated [Os3(CO)8(CNBu t ){μ3-η2-C7H3(2-Me)NS}(μ-H)] (9). Compound 9 reacts with PPh3 at room temperature to give the adduct [Os3(CO)8(PPh3)(CNBu t ){μ-η2-C7H3(2-Me)NS(μ-H)] (10). Compound 8 exists as two isomers in solution whereas 10 occurs in four isomeric forms. The molecular structures of 3, 6, 8, and 10 have been determined by X-ray diffraction studies. [Copyright &y& Elsevier]

Abstract: Heating [Os3(CO)10(μ-dppm)] (1) with two equivalents of PhSSPh in toluene under reflux provided three new triosmium compounds [(μ-H)Os3(CO)7(μ-SPh){μ3-η4-Ph2PCHP(Ph)C6H4}] (2), [Os3(CO)8(μ-SPh)2(μ-dppm)] (3) and [(μ-H)Os3(CO)7(μ-η2-SC6H4)(μ-SPh)(μ-dppm)] (4) in 20%, 21% and 26% yields, respectively. In contrast, a similar reaction of 1 with two equivalents of PhTeTePh in refluxing toluene gave the binuclear compound [Os2(CO)4(μ-TePh)2(μ-dppm)] (6) in 15% yield, and two 50 electron isomeric compounds 5 and 7 with the formula [Os3(CO)8(μ-TePh)2(μ-dppm)] in 20% and 23% yields, respectively. Thermolysis of 3 at 110°C afforded 4 in 53% yield which on further thermolysis in refluxing octane at 128°C gave 2 in 45% yield. Thermolysis of 3 in refluxing octane also gave 2 in 50% yield. The new compounds, 2–7, were all spectroscopically characterized, and the X-ray structures of 2, 3 and 7 have been determined. Compound 2 contains a bridging SPh ligand and a μ3,η4-Ph2PCHP(Ph)C6H4 ligand, formed by two kinds of C–H activation, including orthometallation of a phenyl group as well as an unusual activation of the methylene group of the dppm ligand. The molecular structure of 3 reveals that two SPh groups span the open Os–Os edge of the Os3 triangle, while the dppm ligand bridges one of the closed Os–Os edges. In compound 7, one TePh group spans the open Os–Os edge, while the other spans one of the two closed Os–Os edges and the dppm ligand bridges the third Os–Os vector. [Copyright &y& Elsevier]

Abstract: Treatment of the electronically unsaturated cluster [(μ-H)Os3(CO)8(Ph2PCH2P(Ph)C6H4)] (1) with HCl gas at ambient temperature in dichloromethane afforded (μ-H)Os3(CO)8(μ-Cl)(μ-dppm) (2) and [(μ-H)Os3(CO)7(η1-Cl)(μ-Cl)2(μ-dppm)] (3). Thermolysis of 2 at 110 °C led to an isomer of 2, 4. A similar reaction of 1 with HBr gas gave [(μ-H)Os3(CO)8(μ-Br)(μ-dppm)] (5) as the only product which does not isomerize at 110 °C. In sharp contrast, treatment of 1 with HF gas gave the protonated species [(μ-H)2Os3(CO)8(Ph2PCH2P(Ph)C6H4)]+ (6). Treatment of 1 with CF3CO2H also gave cation 6 whereas CH3CO2H yielded [(μ-H)Os3(CO)8(μ-η2-CH3CO2)(μ-dppm)] (7). Structures of 2, 3, 4 and 6 were established crystallographically. In 2, both the chloride and the hydride ligands simultaneously bridge the same Os–Os edge and the dppm spans another Os–Os bond whereas in 4, all the three ligands bridge the same Os–Os edge. Compound 3 is comprised of an open Os3 arrangement in which one chloride bridges the open Os⋯Os edge, another chloride and a hydride mutually bridge an Os–Os bond and the third chloride is terminally coordinated to one of the Os atoms of the dppm bridged edge. The cation 6 consists of a triangle of osmium atoms in which the shortest Os–Os edge is bridged by a hydride and the metallated phenyl ring and the longest edge is bridged by another hydride and the diphosphine ligand. [Copyright &y& Elsevier]