Excess PMe3 Research Articles

Reactions of phenylimidotrichlorobis(triphenyl-phosphine)rhenium(V). Reaction with trimethyl-phosphine and reduction of trimethylphosphine complex to phenylamido complexes of rhenium(I, III). The X-ray crystal structures of phenylamido-(dinitrogen)tetrakis(trimethylphosphine)-rhenium(I) and phenylamido(buta-1,3-diene)-tetrakis-(trimethylphosphine)rhenium(I)

The interaction of Re(NPh)Cl 3(PPh 3) 2 with PMe 3 gives Re(NPh)Cl 3(PMe 3)(PPh 3) or Re(NPh)Cl 3(PMe 3) 2 depending on conditions. In the presence of excess PMe 3 the phenylimido compounds in tetrahydrofuran are reduced by sodium amalgam giving products whose nature depends on the atmosphere (Ar, N 2, H 2 CO, butadiene) used. The following compounds have been characterised: Re(NHPh)(N 2)(PMe 3) 4, ReH(NHPh)(η′-CH 2PMe 2)(PMe 3) 4, Re(H) 2(NHPh)(PMe 3) 4, Re(NHPh)(CO) 2(PMe 3) 3, Re(NHPh)(CO) 3(PMe 3) 2, Re(NHPh)(η 4-C 4H 6)(PMe 3) 3 and Re(NPh)Cl 2(PMe 3) 3. The structures of Re(NHPh)(N 2)(PMe 3) 4 ( 3) and Re(NHPh)(C 4H 6)(PMe 3) 3, ( 8) have been confirmed by single-crystal X-ray diffraction studies. ( 3) is monoclinic, space group P2 1/ n with a = 9.574(2), b = 19.528(3), c = 14.385(3)Å and β = 99.06(2)°; ( 8) is orthorhombic, space group Pbc2 1, with a = 12.207(2), b = 13.884(2), c = 14.242(2)Å. The structures were solved via the heavy atom method and refined by least squares to R values of 0.065 and 0.062 for 3249 and 2009 observed diffractometer data, respectively. In the dinitrogen complex the N 2 and NHPh ligands adopt a cis configuration with ReN bond lengths of 1.955(13) and 2.200(14)Å, respectively. In the butadiene complex, whose structure is not well defined due to disorder and/or pseudo symmetry correlation effects, the ReN (amido) distance is 2.13(3)Å.

Spectroscopic and gravimetric study of the adsorption of trimethylphosphine on co-zeolites

The adsorption of trimethylphosphine on dehydrated and partially dehydrated CoX zeolites does not give trimethylphosphine coordination complexes. The reflectance spectra can be interpreted as due to complexes with three lattice oxygens and one extra lattice ligand coordinated to Co 2+ along the trigonal axis of the zeolite. On fully dehydrated CoX zeolites the strength of the extra lattice ligand is equal to the strength of the lattice oxygens with 10 D q = 4993 ± 52 cm −1. For partially dehydrated CoX the extra lattice ligand strength is 14–20% larger than the lattice oxygens ligand strength. The exact chemical identification of this extra lattice ligand was not possible. On CoY zeolites low spin square pyramidal [Co(PMe 3) 5] 2+ complexes are formed together with complexes which are probably of the form [Co(O l) 3PMe 3] 2+. The former can only be synthesized in excess PMe 3, the latter are thermally stable up to ∼390°K. In every case, these complexation reactions are hampered by chemisorption on the surface.

Complexation and chemisorption of trimethylphosphine on Ni zeolites

After room temperature saturation of dehydrated NiY with trimethylphosphine two complexes are formed in the supercages. They are identified and quantified by reflectance spectroscopy as 0.9[Ni(PMe3)5]2+ per unit cell and 6–8[(O1)3—Ni—PMe3]2+ per unit cell (O1 is a lattice oxygen). The former is diamagnetic and trigonal bipyramidal, the latter is paramagnetic and compressed tetrahedral. [Ni(PMe3)5]2+ is only stable in excess PMe3, while the mono-phosphine complex is stable to ≈ 383 K in vacuo. On NiX only the paramagnetic compressed tetrahedral complex is formed. The ligand field parameters of this complex were calculated.Chemisorption on lattice and extralattice oxygens gives strongly held OPMe3, OP(OMe3)3 and a range of decomposition products such as CO, CO2, H2O, hydrocarbons and oxygenated P on the surface. These products were qualitatively identified by i.r. and mass spectrometry.