Ligands coordination modes

Interestingly, on warming a solution of 94 the phosphine ligand dissociates to afford the new complex 95. An X-ray diffraction study of the latter complex indicates that the phosphinocarbene behaves as a 4-electron ligand (coordination mode B).86... 

Fig. 26 Salen-Co(III) complex 30 with unusual bidentate ligand coordination mode and proposed copolymerization mechanism...

Ligand Coordinate mode No. of electrons Ligand Coordinate mode No. of electrons... 

Boron-boron bond, formation, 194 Boron-boron single bond, 193 Boron-centered ligands, coordination modes, 165... 

Other spectroscopic techniques that have been used in the study of dppf complexes are XPS, UPS [43] and UV/VIS spectroscopy. XPS provides useful complementary information on the differentiation of pendant and coordinated phosphines [42,80]. Caution needs to be exercised, however, as P(2p) core binding energy is not very sensitive towards changes in the ligand coordination mode or the oxidation state of the metal [42]. The electronic absorption spectra of dppf and MCl2(dppf-P, P ) complexes (M = Co, Ni, Pd, Pt, Zn, Cd, Hg) exhibit an easily detected band at 405—465 nm, attributed to a transition in the ferrocenyl moiety [43]. The presence of any iron-to-metal bonding is usually indicated by an intense ct - a transition [21], as evident in the electronic spectrum of [Pd(dppf-P,P )(PPh3)][BF4]2, 3 [40]. 

If one wants to estimate the ee via/lF g 9 (cf Regioselectivity), it is necessary to consider all possible ligand coordination modes (for example, all possible coordination modes (axial-equatorial ae/equatorial-equatorial ee) are shown in transition states 8,9 for a C2-symmetric bidentate phosphine ligand (e.g., LIO). In the case of Cl symmetry, each coordination mode is duplicated). Each coordination mode contributes with its asymmetric induction to the total stereoselectivity. To achieve high ee values, at least one of the following requirements should be met [7, 37]. 

Ligand coordination mode Electron donor number... 

Donor atoms set Stability of metal-ligand bonds Electron configuration of the metal LabUizing effect on other ligands Coordination mode Denticity... 

The preparation of [Cu(4,4 -bipy)(ccnm = carbamoyl-cyanonitrosomethanide)2] is also dependent on the reaction conditions. Moreover, a solid-state transformation from a ID chain to a 3D network is obtained by either grinding or evaporation of lattice solvent, with a significant change in the ligand coordination mode (Fignre 12). ... 

Secondary building units Molecular complexes and clusters in which ligand coordination modes and metal coordination geometries are used to form extended networks using polytopic linkers. 

To draw a conclusion about the isomerization mechanism of the oximato complexes, one should consider the problem of the effect of the ligand coordination mode in a transition state on the and ls.S values. 

Reactions of the cationic Ir(l) complexes [Ir(cod)(xyliphos)]BF4 and [Ir(cod)(K -ArN=C(Me)CH20Me)]BF4 with I2 resulted in transformations involving C-H activation of the 1,5-cyclooctadiene ligand. Although the current evidence does not allow precise formulation of all the species which participate in the catalytic cycle, the results summarized above provide some important observations concerning ligand-coordination modes and interconversions. 

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