98703-54-9Relevant academic research and scientific papers
Use of electron-rich η6-arylphosphine complexes of molybdenum (0) as ligands in group 6 metal carbonyl complexes
Luck, Rudy L.,Morris, Robert H.
, p. 349 - 364 (2007/10/02)
The reactions of M(CO)6 M = Cr, Mo, W and Mo(η5-PhPPh2)(dppe(L), dppe = PPh2CH2CH2PPh2, L = CO, (L1CO), L = PMe3, (L1P) in benzene under photolysis lead to the following dimeric species M(CO)5(L2CO) and M(CO)5(L1P).Here the free phosphorus of the donor complex coordinates to M(CO)5 without metal-metal bond formation; a Cotton-Kraihanzel force constant analysis indicates that the ordering of e-donor ability is L2P > L1CO > PPh3.Similarly treating the new complex Mo(η6-PhPMePh)(dppe)(P(OMe)3), (L2P) with Mo(CO)6 under photolysis gives the dimer Mo(CO)5(L2P).Heating individual solutions of complexes L1CO, L1PMo(η6-PhPMePh)(dppe)(CO), (L2CO) and L2P in the presence of stoichiometric equivalents of M(CO)4(pip)2, M = Mo or W, pip = piperidine yields Mo(CO)4(pip)(L1CO), W(CO)4(pip)(L1CO), Mo(CO)4(pip)(L1P), W(CO)4(pip)(L2CO) and Mo(CO)4(pip)(L2P).The futher thermal reactions of W(CO)4(pip)(L1CO), W(CO)4(pip)(L2CO) and Mo(CO)4(pip)(L2P) with phophines or phosphite result in the substitution of the piperidine ligand and formation of W(CO)4(PMe2Ph)(L1CO), W(CO)4(PMe2Ph)(L2CO), Mo(CO)4(P(OMe)3)(L2P) and Mo(CO)4(PMe3)(L2P).Complexes are characterised by IR, 1H and 31P NMR spectroscopy.The cone angle for L1CO is determined to be 155 +/- 5 deg by comparing the cis/trans equilibrium ratio for its complex W(CO)4(PMe2Ph)(L2CO) to literature values for other W(CO)4(PMe2Ph)(L) complexes.The bimetallics containing L1CO or L2CO show an irreversible one electron oxidation wave associated with the metallophosphine ligand; those containing L1P or L2P show one reversible oxidation at a more positive potential to that of the free metallophosphine ligands and a second irreversible oxidation.
THE INFLUENCE OF THE STERIC PROPERTIES OF THE LIGANDS PR2Ph AND L ON THE FORMATION AND PROPERTIES OF THE COMPLEXES Mo(η6-PhPR2)(L)(PPh2CH2CH2PPh2), R = Et, L = PPhEt2 and R = Ph, L = PPh3, PR'3, CO, CNR, N2, H2
Frizzell, James J.,Luck, Rudy L.,Morris, Robert H.,Peng, Shane H.
, p. 243 - 256 (2007/10/02)
The reduction of MoCl4(DPPE) (DPPE = PPh2CH2CH2PPH2) with Mg or Na/Hg in the presence of 2 PPhR2 under Ar results in the formation of the new complexes Mo(η6-PhPR2)(PPhR2)(DPPE) when R is Ph(Ia) or Et(II).No η6-PhPR2 complex is obtained when R is Me because this small ligand forms strong Mo-P ?-bonds; nor is one obtained for R = Cy because of too much steric crowding.The limits for η6-complexation can be quantified in terms of cone angle sums.Complex Ia is very similar to Mo(η6-PhPMePh)(PMePh2)3 (IIIa) in that both react at similar rates with a variety of small ligands L = PMePh2, PMe2Ph, PMe3, P(OMe)3, N2, CO, CNBut and H2 via dissocation of a labile ?-bonded ligand.Several other less crowded η6-arylphosphinemolybdenum complexes including II do not have labile ligands at 25 degC.The new complexes Mo(η6-PhPPh2)(L)(DPPE) have been characterized by 31P and 1H NMR, IR and gas uptake measurements.Ia has a higher affinity for H2 than IIIa possibly because Mo(η6-PhPPh2)(H)2(DPPE) adopts a non-fluxional trans-configuration.The 31P chemical shift of the η6-bonded ligand in 8 derivatives of Ia and 12 of IIIa correlate with the sum of cone angles of the three ?-bonded ligands in each complex.
