Ligand reducibility

For gold compounds in the high oxidation state (e.g., AuCU , AuFe , AuFs etc.,) we And rather small bond contractions as the electronegative ligands reduce the 6s... 

If the central atom can still take over electrons and if a ligand has lone electron pairs, then these tend to pass over to the central atom to some degree. In other words, the electron pairs of the ligand reduce their mutual repulsion by shifting partially towards the central atom. This applies especially for small ligand atoms like O and N, particularly when high formal charges have to be allocated to them. For this reason terminal O and N atoms tend to form multiple bonds with the central atom, for example ... 

Substitution of the Cp ligands reduces the tendency to dimerize. Introduction of a cyclohexyl group is sufficient for rendering the monomer the only detectable species by CV. The substituted titanocene chlorides open epoxides slower than Cp2TiCl . However, the resulting /J-metaloxy radicals are more... 

The answer is D. This patient s tests indicate that he has severe hypercholesterolemia and high blood pressure in conjunction with atherosclerosis. The deaths of several of his family members due to heart disease before age 60 suggest a genetic component, ie, familial hypercholesterolemia. This disease results from mutations that reduce production or interfere with functions of the LDL receptor, which is responsible for uptake of LDL-cholesterol by liver cells. The LDL receptor binds and internalizes LDL-choles-terol, delivers it to early endosomes and then recycles back to the plasma membrane to pick up more ligand. Reduced synthesis of apoproteins needed for LDL assembly would tend to decrease LDL levels in the bloodstream, as would impairment of HMG CoA reductase levels, the rate-limiting step of cholesterol biosynthesis. Reduced uptake of bile salts will also decrease cholesterol levels in the blood. 

Asymmetric reduction of ketonesLithium aluminium hydride in conjunction with this chiral ligand reduces prochiral aromatic ketones to (S)-secondary alcohols in 90-95% optical yields. Optical yields are lower (10-40% ee) in the case of alkyl aryl ketones. It is superior to (S)-2-(anilinomethyl)pyrrolidine for this reduction. Evidently the two methyl groups enhance the enantioselectivity. 

Replacement of one of the CO groups of a metal hexacarbonyl by another ligand reduces the symmetry from Oh to C4v. 

An exemplary series of phosphines that illustrates the ligand-reducing tendency toward Re2Clf as a function of phenyl substitution is PEt3, PEt2Ph,... 

All of these metal complexes are isoelectronic and isostructural with each other. Upon coordination of the carbon monoxide to the nickel(O) centre, the metal ion acquires negative charge. The carbon monoxide ligand possesses empty 7r -orbitals, and back-donation from the metal to the ligand reduces the electron density on the metal. 

Figure 5. Dimensional reduction of ResSegC via incorporation of T1C1. Black, shaded, and white spheres represent Re, Se, and Cl atoms, respectively. Each added equivalent of T1C1 supplies another terminal chlorine ligand, reducing connectivity.

Fig. 7 One-bond metal-ligand reduced nudear spin-spin coupling constants (absolute values) for 5d metal complexes. Scalar relativistic ZORA DFT results (VWN functional) versus experimental values. A few data points for Pb are also included. Data taken from Refs. [45,123]. The line is not a fit but indicates where Ka c = Kexp. The different markers indicate the different metals. For not octahedrally or not tetrahedrally coordinated metal centers, the first coordination shell was completed with solvent molecules, as described in Ref. [124]...

The structure of cyclo-di-p- bis-[2-(NiV-dimethylamino)ethyl]disulphide dicop-per(i) tetrafluoroborate, Cu2(Me2NCH2CH2SSCH2CH2NMe2)(BF4)2, contains a central CuSSCuSS ring (152), the Cu1 being in a very badly distorted tetrahedral environment. The complex is prepared by reaction of the ligand with either Cu1 or Cu11 ions in the latter case, the ligand reduces the metal to the required oxidation state.661... 

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