A suitable representation of the regional gravity field is used to estimate relative offsets between national height system realizations in Europe. The method used is based on a gravimetric approach and benefits from the significant improvements in the determination of the global gravity field by the recent satellite gravity missions the Gravity Recovery and Climate Experiment (GRACE) and the Gravity field and steady-state Ocean Circulation Explorerr (GOCE). The potential of these missions for the unification of height reference frames is analyzed in terms of accuracy and spatial resolution. The results of the gravimetric approach are compared to the independent results of the geodetic leveling approach. Advantages and drawbacks of both methods are discussed.
Mixtures of aromatic nitro compounds and Fe (CO)5 are reduced by the action of light or 60Co-γ to the corresponding nitroso compounds, which simultaneously form monomeric or dimeric irontricarbonyl complexes. The influence of substituents on the structure of these complexes is discussed on the basis of IR and UV data.
By use of Re(CO)5FBF3 the complexes with a single unsupported halide or pseudohalide bridge [Cp(OC)2Fe-X-Re(CO)5]+ BF4- (X=Cl, I, PPh2), (OC)5M-X-Re(CO)5 (M=Cr, W; X=Br, I, CN, NCS, SH), (OC)5W-N≡C-C[-C≡N-Re(CO)5]2+ BF4-, Cp(OC)(NC)Fe-C≡N-Re(CO)5, and [(OC)5Re-N3-Re(CO)5]+ BF4- have been synthesized.