73690-58-1

Upstream product

• 12128-81-3 tricarbonyl(η6-cycloheptatriene)tungsten 
• 74-85-1 ethene 
• 2622-14-2 tricyclohexylphosphine 
• 73690-56-9 (P(C₆H₁₁)3)2W(CO)3 
• 191412-45-0 W(CO)3(P(C₆H₁₁)3)2 
• 73690-56-9 W(CO)3(PCy₃)2 

Relevant academic research and scientific papers

Direct measurements of rate constants and activation volumes for the binding of H2, D2, N2, C2H 4, and CH3CN to W(CO)3(PCy3) 2: Theoretical and experimental studies with time-resolved step-scan FTIR and UV-Vis spectroscopy

Pulsed 355 nm laser excitation of toluene or hexane solutions containing W-L (W = mer,trans-W(CO)3(PCy3)2; PCy 3 = tricyclohexylphosphine; L = H2, D2, N 2, C2H4, or CH3CN) resulted in the photoejection of ligand L and the formation of W. A combination of nanosecond UV-vis flash photolysis and time-resolved step-scan FTIR (s2-FTIR) spectroscopy was used to spectroscopically characterize the photoproduct, W, and directly measure the rate constants for binding of the ligands L to W to reform W-L under pseudo-first-order conditions. From these data, equilibrium constants for the binding of L to W were estimated. The UV-vis flash photolysis experiments were also performed as a function of pressure in order to determine the activation volumes, ΔV?, for the reaction of W with L. Small activation volumes ranging from -7 to -3 cm3 mol-1 were obtained, suggesting that despite the crowded W center an interchange mechanism between L and the agostic W...H-C interaction of one of the PCy3 ligands (or a weak interaction with a solvent molecule) at the W center takes place in the transition state. Density functional theory (DFT) calculations were performed at the B3LYP level of theory on W with/without the agostic C-H interaction of the PCy3 ligand and also on the series of model complexes, mer,trans-W(CO)3(PH3)2L (W′-L, where L = H2, N2, C2H4, CO, or n-hexane) in an effort to confirm the infrared spectroscopic assignment of the W-L complexes, to simulate and assign the electronic transitions in the UV-vis spectra, to determine the nature of the HOMO and LUMO of W-L, and to understand the agostic C-H interaction of the ligand vs solvent interaction. Our DFT calculations indicate an entropy effect that favors agostic W...H-C interaction over a solvent σ C-H interaction by 8-10 kcal mol -1.

Comparison of H-H versus Si-H σ-Bond Coordination and Activation on 16e Metal Fragments. Organosilane, N2, and Ethylene Addition to the Agostic Complex W(CO)3(PR3)2 and Dynamic NMR Behavior of the Latter

Variable-temperature 31P{1H} NMR spectroscopy of the agostic complexes M(CO)3(PCy3)2 (M = Mo, W) indicates dynamic behavior as evidenced by collapse below -20°C of a singlet to an AB signal plus a shifted singlet. The inequivalency of the phosphines is possibly due to the presence of conformational isomers resulting from hindered rotation of the M-P bond or, less likely, a geometric isomer with pseudo-as PCy3 ligands. Further studies on the coordination chemistry of W(CO)3(PR3)2 (R = iPr, Cy) were performed. The bridging dinitrogen complex [W(CO)3(PiPr3)2]2(μ-N 2) (1) was cleanly formed in the reaction of W(CO)3(PiPr3)2 with N2. Complex 1 was structurally characterized and compared with other bridging dinitrogen compounds of tungsten. The ethylene complex W(CO)3(PCy3)2 (η2-C2H4 (2) was synthesized and characterized by X-ray crystallography in order to compare the binding mode of ethylene with that of H2. Phenylsilane reacted with W(CO)3(PR3)2 (R = iPr, Cy) to form the thermally unstable oxidative addition (OA) products WH(SiH2Ph)(CO)3(PR3)2 (3, R = Cy; 4, R = iPr). Diphenylsilane reacted with W(CO)3(PiPr3)2 at 60°C to form the bridging silyl species [W(CO)3(PiPr3)(μ-SiHPh2)]2 (5), which was confirmed by spectroscopic techniques and X-ray crystallography to have two 3-center 2-electron W·H·Si interactions. Detailed comparisons of the binding and activation of silanes versus H2 on various 16e metal centers suggest a high degree of similarity, but relative ease of OA depends on the electrophilicity of the metal-ligand fragment and other factors such as bond energetics. Increasing the electrophilicity of the metal center (e.g., adding positive charge) may aid in stabilizing alkane coordination.

Five-co-ordinate Molybdenum and Tungsten Complexes, , which Reversibly add Dinitrogen, Dihydrogen, and Other Small Molecules

New complexes of molybdenum and tungsten with dinitrogen and other small molecules, trans- (L = N2, H2, C2H4, or SO2), have been synthesized by the reaction of with 2PCy3 in the presence of L; removal of L yield