Ligand doubly

Unusual ortho metallation of one or two phenyl groups of C(PPh3)2 is observed by reacting with some second and third row group 9 and 10 transition metal compounds. As mentioned before, transition metal precursors were compounds with either vacant coordination sites or easily removable ligands. Doubly ortho metalated compounds can also be seen as pincer carbodiphosphoranes. 

An interesting fluoro-containing cluster was reported in 1990 (Watson et al., 1990). In this cluster, formulated as [Yb5Cp6(/i4-F)(/i3-F)2 (/i-F)g], there are three different kinds of bridging fluoro ligands, doubly, triply, and quadruply bridging (Figure 34). The and four Yb atoms... 

Compounds in which the group 14 ligand doubly bridges metals in a cluster without further reaction... 

Figure 3. Molecular-orbital diagrams as obtained by the ROHF method. Dashed lines indicate MOs dominated by the metal d-orbitals, the solid lines stand for doubly occupied or virtual ligand orbitals. Orbitals which are close in energy are presented as degenerate the average deviation from degeneracy is approximately 0.01 a.u. In the case of a septet state (S=3), the singly occupied open-shell orbitals come from a separate Fock operator and their orbital energies do not relate to ionization potentials as do the doubly occupied MOs (i.e. Koopmann s approximation). For these reasons, the open-shell orbitals appear well below the doubly occupied metal orbitals. Doubly occupying these gives rise to excited states, see text.

Figure 4.6 An enantioselec-live MOF epoxidation catalyst. Zn-(l,4 -biphenyldicarboxylate) sheets in the ab direction are connected by functionalized Mn-salen ligands to form a doubly...

The dissociation equilibrium constants that determine the formation of ABR and ABR are so large (i.e., the corresponding affinities are so small) that the quantities of these doubly liganded forms are negligible. In effect, the binding of A and B is mutually exclusive. If, in addition, the affinity of B for the active form of the receptor is very low,... 

Platinum(III) complexes are remarkably rare and most examples date from less than 30 years ago. The great majority are dimeric species with only a few authenticated stable monomers reported. Most of the dimers are bridged by bidentate ligands and are almost exclusively doubly or quadruply bridged, the latter giving rise to the classic lantern structure. 

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