Structure and reactivity of tungsten(II) and molybdenum(II) compounds containing an MM′ bond

Ring Opening Metathesis Polymerization of Norbornene and Derivatives by the Triply Bonded Ditungsten Complex Na[W2(µ-Cl)3Cl4(THF)2]·(THF)3

“…Among them, protagonists are those of ruthenium, molybdenum and tungsten. For the last two, the following major categories have been classified [1][2][3][4][5][6][9][10][11] ) exhibiting small to moderate activity; these become very reactive when activated by organometallic cocatalysts (e.g., SnMe 4 , AlEt 3 ); (ii) discreet alkylidenes, such as the well-defined Katz [(OC) 5 W=C(Ph)R] (R = OMe, Ph) [12] and Schrock ([M(NAr)(CHR)(OR') 2 ] (M = Mo, W; Ar = aryl; R = aryl or alkyl; R' = CMe 3 , CMe 2 CF 3 , CMe(CF 3 ) 2 , C(CF 3 ) 3 ) [13] catalysts and their numerous variations. Despite the abundance of mononuclear catalytic systems, there is only a limited number of bimetallic multiply metal-metal bonded complexes inducing the ROMP of NBE.…”

Tungsten(II)-initiated ring-opening metathesis polymerization and other C–C bond forming reactions of 5-vinyl-2-norbornene

“…: +48 71 375 7221; fax: +48 71 328 2348. [15][16][17][18]. These complexes have been prepared in photochemical oxidative addition reaction of W(CO) 6 and tin or germanium tetrachloride.…”

“…Recently, the research works in our group and others have indicated that tungsten(II) complexes provide a rich variety of reactions with unsaturated hydrocarbons and can be used as catalysts for the metathesis of acyclic olefins and ROMP of cyclic olefins [10][11][12][13][14][15][16][17]. Among tungsten(II) compounds, the heterobimetallic complexes with a direct W-Sn or W-Ge bond have attracted particular interest owing to their strikingly different reactivity relative to the similar tungsten(II) complexes without metal-metal bond.…”

Stannylation of unsaturated carbon–carbon bonds by tin tetrachloride

“…In reaction of carbonyl complexes such as [M(CO) 6 ] or [M(CO) 4 L 2 ] (L ¼ nitrogen or phosphorous donor ligands) and SnCl 4 , binuclear and mononuclear complexes of the type [(m-Cl) 3 {M 2 (SnCl 3 )(CO) 7 }] and [MCl(SnCl 3 )(CO) 3 L 2 ] (M ¼ Mo, W) are formed. These molybdenum(II) and tungsten(II) complexes containing trichlorostannyl ligand readily react with bicyclo[2.2.1]-hept-2-ene (norbornene, (nbe)) and bicyclo[2.2.1]-hepta-2,5-diene (norbornadiene (nbd)) to initiate the ring-opening metathesis polymerization (ROMP) in dichloromethane solution at room temperature [7,8], but in reaction with terminal alkynes they initiate cyclotrimerization and polymerization reactions [9].…”

“…These molybdenum(II) and tungsten(II) complexes containing trichlorostannyl ligand readily react with bicyclo[2.2.1]-hept-2-ene (norbornene, (nbe)) and bicyclo[2.2.1]-hepta-2,5-diene (norbornadiene (nbd)) to initiate the ring-opening metathesis polymerization (ROMP) in dichloromethane solution at room temperature [7,8], but in reaction with terminal alkynes they initiate cyclotrimerization and polymerization reactions [9]. In aromatic hydrocarbon solution, the heterobimetallic complex [(m-Cl) 3 {W 2 (SnCl 3 )(CO) 7 }] is, however, a good catalyst for the hydroarylation of nbe [10]. Very interesting catalytic activity has also been observed for other complexes containing trichlorostannyl ligands; e.g.…”