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[Display omitted] Reactions of the electron defficient triosmium [Os 3 (CO) 9 (μ 3 -η1,κ1-C 9 H 6 N)(μ-H)] with Ph 3 EH (E = Si, Ge, Sn) have been investigated. The reactions of quinoline-capped triosmium cluster [Os 3 (CO) 9 (μ 3 -η1,κ1-C 9 H 6 N)(μ-H)] (1) with Ph 3 EH (E = Si, Ge, Sn) have been investigated. Cluster 1 reacts with Ph 3 EH in refluxing benzene to afford [Os 3 (CO) 9 (EPh 3)(μ-η1,κ1-C 9 H 6 N)(µ-H) 2 ] (2a , E = Si; 2b , E = Ge; 2c , E = Sn) and [Os 3 (CO) 8 (EPh 3)(μ 3 -η1,κ1-C 9 H 6 N)(µ-H) 2 ] (3a , E = Si; 3b , E = Ge; 3c , E = Sn). Control experiments confirm that 2 is a precursor of 3. Cluster 2 is formed via oxidative-addition of E–H bond to 1 whose decarbonylation leads to the formation of 3. The molecular structures of all the new clusters (except 3c) have been determined by X-ray crystallography. Both 2 and 3 exist as a pair of isomers in solution, and their fluxionality in solution has been probed by VT NMR experiments. [ABSTRACT FROM AUTHOR]

Abstract: The factors affecting the rate of silica leaching in alkaline aqueous media from surface silanized, nanoporous, amorphous, silica gels and from silanized silica gels that have been modified with polyamines to form the previously reported silica polyamine composites (SPCs), BP-1 and BP-2 have been investigated. Silanization with alkyl trichlorosilanes slows the rate of silica leaching relative to the unmodified silica gels. The use of bulkier aryl silanes somewhat decreases the silica leaching under the same conditions. Interestingly, after modification of the silanized silica with poly(allylamine) (PAA) to make BP-1, the leaching increases, but subsequent modification of the SPC with chloroacetic acid to make BP-2, quenches this increase. A mechanism explaining these results is discussed. Analogous composites have been prepared using sol–gel chemistry. These materials were characterized and their silica leaching properties were compared with the original BP-1. CPMAS 13C and 29Si NMR of the various surfaces have been applied to better understand the nature of the modified surfaces. Significant changes in the nature of the surface siloxanes are observed for the different matrices and on their conversion to the polyamine composite. Scanning electron microscopy and pore size distributions for the composites made from commercial silica gel and from sol–gel chemistry are also reported and compared. [Copyright &y& Elsevier]

Abstract: Treatment of [(μ-H)Os3(CO)10(μ-OMe)] (1) with dppm {dppm=bis(diphenylphosphino)methane} at 110°C gave the known compound [Os3(CO)10(μ2-η2-dppm)] (2) and the new compound [(μ-H)Os3(CO)8(μ-OMe)(μ2-η2-dppm)] (3). A similar reaction of 1 with dppe {dppe=bis(diphenylphosphino)ethane} afforded two products, [(μ-H)Os3(CO)8(μ-OMe)(μ1-η2-dppe)] (5) and [(μ-H)Os3(CO)8(μ-OMe)(μ2-η2-dppe)] (6) which differ in the mode of bonding of the dppe ligand. The reaction of 1 with dppp {dppp=bis(diphenylphosphino)propane} at 110°C gave exclusively [(μ-H)Os3(CO)8(μ-OMe)(μ2-η2-dppp)] (7) which exists as two isomers in solution. Compounds 2, 3, and 5–7 are also obtained in almost similar yields from reactions of [(μ-H)Os3(CO)9(μ-OMe)(MeCN)] (4) with the appropriate diphosphine at ambient temperature. The reaction of 1 with PPh2H at 110°C gave the new compounds [(μ-H)Os3(CO)9(μ-OMe)(PPh2H)] (8) and [(μ-H)2Os3(CO)7(μ-PPh2)2(PPh2H)] (10) and the previously reported compound [(μ-H)2Os3(CO)8(μ-PPh2)2] (9). The molecular structures of 3 and 8 were determined by single crystal X-ray diffraction. In compound 3, the dppm ligand bridges the same Os–Os edge as the hydride and the methoxide ligand. In 8, the PPh2H ligand occupies a ‘pseudo’ axial site on one of the osmium atoms bearing the bridging hydride and methoxide ligand. [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]

The reaction of [Ru3(CO)10(mu-dppm)] (1) with dppmSe at 66 °C affords [Ru3(CO)8(mu-dppm)2] (2), [Ru3(CO)7(mu3-CO)(mu3-Se)(mu-dppm)] (3), [Ru3(CO)5(mu3-CO)(mu3-Se)(mu-dppm)2] (4) and [Ru3(CO)6(mu3-CO)(mu3-Se)(mu-dppm)(mu1-Ph2PCH2P(double bond; length as m-dashO)Ph2)] (5) in 7%, 5%, 9% and 33% yields, respectively. A similar reaction between 1 with dppmS gives [Ru3(CO)7(mu3-S)2(mu-dppm)] (6), [Ru3(CO)7(mu3-CO)(mu3-S)(mu-dppm)] (7) [Ru3(CO)5(mu3-CO)(mu3-S)(mu-dppm)2] (8) and [Ru3(CO)6(mu3-CO)(mu3-S)(mu-dppm)(mu1-Ph2PCH2P(double bond; length as m-dashO)Ph2)] (9) in 8%, 7%, 14% and 35% yields, respectively. Treatment of 1 with PhSeSePh at 66 °C affords the dinuclear compound [Ru2(CO)4(mu-SePh)2(mu-dppm)] (10) in 14% yield. Thermolysis of 5 and 9in refluxing toluene at 110 °C gives 4 and 8, respectively. The molecular structures of 4, 9 and 10 have been determined by single-crystal X-ray diffraction studies. The cores of the new clusters 4, 5, 8 and 9 consist of metal triangles capped by mu3-sulfur or selenium atoms with the bidentate ligand bridging in equatorial positions. In compounds 4 and 8, two bidentate dppm ligands bridge the Ru3 triangle in such a way that each ligand bridges two ruthenium atoms and one Ru-Ru edge remains unbridged. Compounds 5 and 9 contain one bridging dppm ligand and one dangling dppm mono-oxide ligand Ph2PCH2P(double bond; length as m-dashO)Ph2 coordinated to the rear metal atom at an equatorial position. The molecular structure of 10 shows classical "sawhorse" structure with two bridging SePh ligands as well as the dppm ligand. [ABSTRACT FROM AUTHOR]