Effective core potential catalyst

Two levels of theory are commonly used in the design of the nickel-based catalysts shown in Figure 11 Density Functional Theory (B3LYP functional used with effective core potentials for Ni and 6-3IG for everything else in the complex) and molecular mechanics (both the UFF (4) and reaction force field, RFF (85,86) are used) (87). All these methods are complementary, and the experiments are guided from the results of several calculations using different molecular modeling techniques. 

Importantly, this study has been carried without modeling the catalyst and the reagents employed for the experiments (Fig. 6.2, X = Me, Y = H). The B, C, and H atoms have been described using the standard 6-31 G(d,p) basis set, while for the more electronegative O and N atoms the 6-3 l-nG(d) basis set including diffuse functions has been employed. On the other hand, for Pd and Br atoms the SDD effective core potential [57] and its associated double- basis set have been adopted. Additionally, for Pd f-polarization functions have been also added (exponent = 1.472) [58], whereas for Br both d-polarization (exponent = 0.428) and p-diffuse (exponent = 0.0376) functions [59] have been added. 

The co-reduction of the Pt and Ru cations resulted in the formation of the core/shell microstructured catalysts due to the preferential reduction of the Pt cation. In this section, a strategy for synthesizing well-mixed Pt-Ru bimetallic nanoparticle catalysts is presented. A key for the synthesis is decreasing difference of effective reduction potentials between the Pt... 

Examination of the cyclic voltammetry (CV) of the Zn-porphyrin dendrimers in THF and CH2C12 with Bu4N+PF6 (0.1 m) electrolyte revealed first oxidation potentials up to 300 mV (THF) less positive than the corresponding values obtained for the unshielded tetraester, Zn-porphyrin core. These preliminary electrochemical experiments suggested dendritic encapsulation of redox-active chromophores can effectively influence the electrophone environment controlled and well-conceived cascade architecture can lead to new avenues of selective redox catalyst design. 

During the past two decades the homogeneous and heterogeneous catalytic enan-hoselective addition of organozinc compounds to aldehydes has attracted much attention because of its potential in the preparation of optically active secondary alcohols [69]. Chiral amino alcohols (such as prolinol) and titanium complexes of chiral diols (such as TADDOL and BINOL) have proved to be very effective chiral catalysts for such reactions. The important early examples included Bolm s flexible chiral pyridyl alcohol-cored dendrimers [70], Seebach s chiral TADDOL-cored Frechet-type dendrimers [28], Yoshida s BINOL-cored Frechet-type dendrimers [71] and Pu s structurally rigid and optically active BlNOL-functionalized dendrimers [72]. All of these dendrimers were used successfully in the asymmetric addition of diethylzinc (or allyltributylstannane) to aldehydes. 

On a fundamental level, these results demonstrate the behavior of extremely small amounts of Ir and Ru at very positive potentials in a PEM envirOTunent The nature of these extraordinary OER activities needs further elucidatimi both from a practical and fundamental point of view. The thin film morphology could be one of the main factors affecting activity, first of all through the favorable surface to mass ratio and further due to the discontinuous nature of the thinner coatings. Finally, the observed interactions with the substrate and the NSTF perylene core could have an effect both on the activity and stability of the OER catalyst. 

Dimolybdenum quadraple bonds can also act as catalysts for radical addition and polymerisation reactions. Their performance can be tuned by modifying the redox potential of the dimetal core. For example, the carbo)grlate bridged compound Mo2(TiPB)4 ( 4/2 = 0.140 V vs. Fc/Fc ) acts as a catalyst for radical addition reactions of polyhaloalkanes to 1-alkenes and cyclopentene, while the formamidinate and guanidi-nate bridged compounds ( 1/2 = —0.308 V and —0.581 V, respectively) are effective catalysts for the radical polymerisation of methyl methacrylate. 

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