33847-61-9

Upstream product

• 14040-11-0 tungsten hexacarbonyl 
• 23582-02-7 bis(2-diphenylphosphinoethyl)phenylphosphine 
• 81097-61-2 fac-W(CO)3(PMTA) 
• 81097-61-2 W(CO)3(1,1,4,7,7-pentamethyldiethylenetriamine) 

Downstream Products

• 136546-90-2 W(CO)3{P(C₆H₅)(C₂H₄P(C₆H₅)2)2(H)}⁽¹⁺⁾*CF₃SO₃^(1-)=W(CO)3{P(C₆H₅)(C₂H₄P(C₆H₅)2)2(H)}(CF₃SO₃) 

Relevant academic research and scientific papers

Tungsten(VI) hexahydride complexes supported by chelating triphosphine ligands: Protonation to give η2-dihydrogen complexes and catalytic dehydrogenation of cyclooctane to cyclooctene

Reactions of WCl4(PPh3)2·CH2Cl2 with the chelating triphosphine (triphos) ligands PPh(CH2CH2PPh2)2 (PP2), PPh(C6H4-o-PPh2)2 (TP), and MeC(CH2PPh2)3 (P3) in refluxing benzene or toluene give WCl4(triphos) (triphos = PP2 (1), TP (2), P3 (3)). Treatment of 1-3 with LiAlH4 in Et2O at room temperature followed by hydrolysis in THF at 0°C affords WH6(triphos) (triphos = PP2 (4), TP (5), P3 (6)), which are the first tungsten polyhydride complexes supported by a chelating triphosphine ligand. Variable-temperature 1H NMR spectra and T1 data of 4-6 are consistent with the formulation of them as classical hexahydride complexes containing no η2-H2 ligands. Reaction of 4 with Ph3SiH in refluxing THF gives the rare silyl polyhydide complex WH5(SiPh3)(PP2) (7). Protonation of 4-6 with HBF4·OEt2 in CD2Cl2 at 193 K affords the cationic nonclassical η2-H2 complexes [WH7-2x(η2-H2)x(triphos)] + (triphos = PP2 (8), TP (9), P3 (10); x = 1-3). Deprotonation of 8-10 with NEt3 regenerates the parent hexahydrides 4-6 quantitatively. The variable-temperature 1H NMR T1 data for the hydride resonances of 8-10 are consistent with the nonclassical η2-H2 coordination. The alternative formulation of 8-10 as classical heptahydride complexes (i.e., [WH7(triphos)]+) containing no η2-H2 ligand can be ruled out because it would exceed the maximum oxidation state and coordination number of tungsten. In the presence of tert-butylethylene as a hydrogen acceptor, complexes 4 and ReH5(PP2) (11) are active catalysts for the thermal dehydrogenation of cyclooctane to cyclooctene, whereas their analogues containing monodentate phosphine ligands are inactive under similar conditions.

Steric and electronic effects of mono- and tridentate phosphine ligands on the basicities of the metal in tungsten tris(phosphine) tricarbonyl complexes

Titration calorimetry has been used to determine the heats of protonation (ΔHHM) of the fac-W(CO)3(PR3)3 (PR3 = PMePh2 (1), PEtPh2 (2), PMe2Ph (3), PEt2Ph (4), PMe3 (5), PEt3 (6)) and fac-W(CO)3(L3) (L3 = PhP(CH2CH2PPh2)2 (7), MeC(CH2PPh2)3 (8)) complexes with CF3SO3H in 1,2-dichloroethane solvent at 25.0°C. The W(CO)3(PR3)3 and W(CO)3(L3) complexes undergo protonation at the tungsten with 1 equiv of CF3SO3H to form [W(H)(CO)3(PR3)3]CF3SO 3(1H+-6H+) and [W(H)(CO)3(L3)]CF3SO3(7H +,8H+), respectively. For the W(CO)3(PR3)3 (1-6) complexes, the metal basicity (-ΔHHM) generally increases as phosphine basicity (-ΔHHP) increases; the ΔHHM values range from -15.1 kcal mol-1 (PR3 = PMePh2) to -25.0 kcal mol-1 (PR3 = PEt3). However, the trend in the ΔHHM values is also influenced by the steric bulk of the phosphine ligand. Steric crowding in the fac-W(CO)3(PR3)3 complexes is relieved when the complexes are protonated and the phosphine ligands adopt a less crowded arrangement in which they are approximately coplanar with the metal; metal basicity increases as the cone angle (θ) of the phosphine increases. ΔHHM of the tridentate phosphine complex 8 (-10.5 kcal mol-1) with the facially coordinating MeC(CH2PPh2)3 ligand is 6.2 kcal mol-1 less exothermic than that of 7 (-16.7 kcal mol-1) with the flexible PhP(CH2CH2PPh2)2 ligand. The lower basicity of 8 is attributed to a destabilization of the 8H+ product, which is forced by the MeC(CH2PPh2)3 ligand to adopt a structure less favorable than that of 7H+. The ΔHHM values (-18.3 and-20.1 kcal mol-1, respectively) of the Cp*Re(CO)2(PR3) (PR3 = PMe2Ph (9), PMe3 (10)) complexes have also been determined.

W(CO)3(PMTA) (PMTA = MeN(CH2CH2NMe2)2) as a starting material for syntheses of W(CO)3(PR3)3, W(CO)3(η6-arene), and the protonated W(H)(CO)3(PR3)3+ complexes

A new and improved method for the synthesis of M(CO)3(PMTA) (M = W, Mo) from M(CO)6 and PMTA (MeN(CH2CH2NMe2)2) is described.The tridentate nitrogen ligand in W(CO)3(PMTA) is replaced, under relatively mild conditions, by tertiary phosphines (PMe3, PEt3, PMe2Ph, PMePh2, PhP(CH2CH2PPh2)2, CH3C(CH2PPh2)3, and Ph2P(CH2)nPPh2 where n = 1, 2) and arenes (C6H6, MeC6H5, p-Me2C6H4, C6Me6, C6H5Cl), which provides a general synthetic method for the preparation of W(CO)3(PR3)3 and W(CO)3(η6-arene) complexes.The reactions of W(CO)3(L)3 with CF3SO3H in CH2Cl2 solution yield the hydrido derivatives W(H)(CO)3(L)3+ which were characterized by their 1H and 31P NMR spectra at different temperatures.These studies show the W(H)(CO)3(L)3+ complexes to be fluxional as a result of both hydride and phosphine ligand migration.