Ligand fluorinated

For the most electronegative ligand, fluorine, we expect a relativistic destabilization in the Au—F bond, which was indeed determined to be —0.36eV at the coupled cluster level [182,183], Nevertheless, AuF has a sufficiently high dissociation energy of about 3.17 eV and has been identified recently in the gas phase [184]. In solution or in the solid state it would disproportionate to metallic Au and compounds of Au (AuF3 for the solid). However, a carbene-stabilized Au(I) fluoride was synthesized only very recently (see discussion in the next section) [185]. 

As may be seen from the indications above the interpretation of magnetic anomalies as caused by magnetic interactions is not at all quite clear-cut. Fortunately neutron diffraction simplifies matter as it provides a definite proof of those interactions that are cooperative all over the crystal structure and detectable therefore because of spin alignment within magnetic sublattices. Such proofs are missing up to now for the higher fluorides, however. The break-down of Hund s rule for the 4d-and 5i-ions, in most fluorides of which even the weak-field ligand fluorine causes low-spin behaviour, may account for this as well as the different nature of interactions assumed instead. 

Figure 5.6 A diagram showing the electronic changes made in the formation of XeF2 the electrons shown in red are those from the ligand fluorine atoms...

The SbF6 ion has a central antimony atom with a ground state of 5s25p2 which is trivalent. If the 5s electrons were to be unpaired and one promoted to a 5d orbital the antimony would then be five-valent. If it accepted an electron to make it Sb and the electron was accommodated in another 5d orbital the ion would be six-valent and could accept the six electrons from the six ligand fluorine atoms to give a valence shell of six a pairs. This would indicate that the ion should have a regular octahedral shape. 

Addition of electronegative ligands (fluorine) to three- and four-coordinate phosphorus... 

These generalities are obviously dependent to a considerable extent upon the specific atoms connected to the phosphorus and, indeed, it is possible that the observed differences between the triply and quadruply connected phosphorus atoms may be attributed primarily to the individual ligands. Fluorine appears to contribute nearly as much shortening (assuming that the tabulated values for the fluorine bond length axe correct) to the P-F connection in the triply connected as in the quadruply... 

Biffinger JC, Uppaluri S, Sun H, DiMagno SG (2011) Ligand fluorination to optimize preferential oxidation of carbon monoxide by water-soluble rhodium porphyrins. ACS Catal 1(7) 764-771... 

Provided the unshifted centres of the transitions can be located the central-atom hyperfine interaction and value may be determined exactly from an iterative solution of the Breit-Rabi equations. Ligand fluorine hyperfine interactions should be determined from the highest-field transition available where spin-spin decoupling is essentially complete. 

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