He I and He II photoelectron (PE) spectra of [Fe(η-C5H4)2SiMe2] (1), [Fe(η-C5H3Me)2SiMe2] (2), [Fe(η-C5H4)(η-C5Me4)SiMe2] (3), [Fe(η-C5Me4)2SiMe2] (4), [Fe(η-C5H4)2C2H4] (5), and [Fe(η-C5H4)2S] (6) have been measured and assigned. The d bands of 1−5 show less structure than that of ferrocene, consistent with a loss of degeneracy of the e2 orbitals on bending. Compound 6, which has the largest inter-ring angle of the series, shows two separate d bands. The trend in the first ionization energy closely parallels the variation in oxidation potential. Density functional calculations on 1, 5, and 6 give geometries in good agreement with the structures found from X-ray diffraction. Ionization energies calculated were also in excellent agreement with experiment. Good agreement was also found between the calculated d−d transitions and the position of the first spin-allowed band in the optical spectra of 1 and 6. Estimates of strain energy in bending ferrocene and octamethylferrocene were obtained, and octamethylferrocene was shown to be significantly more difficult to bend. Compounds 1 and 6 were both shown to have a low-lying empty orbital, partially located on the ipso carbon, which is a possible site for nucleophilic attack in the polymerization process undergone by these compounds.

Two organically templated layered uranium(VI) phosphates have been prepared under hydrothermal conditions from U 3 O 8 and H 3 PO 4 using either NPr 4 + or NHEt 3 + ions as structure directing agents; both compounds have layered structures which contain infinite chains of edge-sharing [UO 7 ] pentagonal bipyramids cross linked by bridging [PO 4 ] tetrahedra to form two dimensional sheets of [(UO 2 ) n -(HPO 4 ) n 2 1 (PO 4 )] m m2 anions.

The reaction of CpCo(PPh 3 )Me 2 with the N-heterocyclic carbene 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene (IPr) does not result in complete substitution of the PPh 3 , as expected, but rather in an equilibrium mixture of CpCo(PPh 3 )Me 2 , IPr, CpCo(IPr)Me 2 , and PPh 3 . Determination of the equilibrium constants for this unusual reaction over the temperature range 30-50 °C shows that ∆H°) -24.4 ( 1.7 kJ mol -1 , ∆S°) -65.8 ( 5.5 J mol -1 K -1 , and thus that it is entropy factors arising from steric crowding in CpCo(IPr)-Me 2 that prevent complete substitution. Evidence for steric crowding is found in a comparison with the crystal structures of CpCo(PPh 3 )Me 2 , CpCo(IPr)Me 2 , and CpCo(IPr)(CO). The smaller, more basic PMe 3 does displace IPr completely from CpCo(IPr)Me 2 .Phosphine complexes are used extensively in catalytic processes, generally stabilizing reaction intermediates through their electronic and steric properties. 1 N-Heterocyclic carbenes (A, R ) alkyl, aryl

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A new three-dimensional zinc fluorophosphate is prepared by using hydro(solvo)thermal conditions with ZnO, (HF) x •py H 3 PO 4 and 4,4A-bipyridyl; the single-crystal structure is determined.