Ligand properties table

The isomer distribution of the nickel catalyst system in general is similar qualitatively to that of the Rh catalyst system described earlier. However, quantitatively it is quite different. In the Rh system the 1,2-adduct, i.e., 3-methyl-1,4-hexadiene is about 1-3% of the total C6 products formed, while in the Ni system it varies from 6 to 17% depending on the phosphine used. There is a distinct trend that the amount of this isomer increases with increasing donor property of the phosphine ligands (see Table X). The quantity of 3-methyl-1,4-pentadiene produced is not affected by butadiene conversion. On the other hand the formation of 2,4-hexadienes which consists of three geometric isomers—trans-trans, trans-cis, and cis-cis—is controlled by butadiene conversion. However, the double-bond isomerization reaction of 1,4-hexadiene to 2,4-hexadiene by the nickel catalyst is significantly slower than that by the Rh catalyst. Thus at the same level of butadiene conversion, the nickel catalyst produces significantly less 2,4-hexadiene (see Fig. 2). 

Considering the different calculated values for an individual complex in Table 11, it seems appropriate to comment on the accuracy achievable within the Hartree-Fock approximation, with respect to both the limitations inherent in the theory itself and also to the expense one is willing to invest into basis sets. Clearly the Hartree-Fock-Roothaan expectation values have a uniquely defined meaning only as long as a complete set of basis functions is used. In practice, however, one is forced to truncate the expansion of the wave function at a point demanded by the computing facilities available. Some sources of error introduced thereby, namely ghost effects and the inaccurate description of ligand properties, have already been discussed in Chapter II. Here we concentrate on the... 

Molecular triangle lOd contains chiral dihydroxy functionalities and has been used for highly enantioselective catalytic diethylzinc additions to aromatic aldehydes, affording chiral secondary alcohols upon hydrolytic work-up, as shown in Eq. (4.2) (Table 4.2) [22]. With Ti(IV) complexes of lOd as catalyst, chiral secondary alcohols were obtained in >95% yield and 89-92% ee for a wide range of aromatic aldehydes with varying steric demands and electronic properties (Table 4.2). In comparison, when the free ligand 6,6 -dichloro-4,4 -diethynyl-2,2 -binaphthol was used instead of... 

An attempt has been made to study the relative ligand properties of CO and NO by examining the UPS of the isoelectric molecules Ni(CO)4, Co(CO)3NO, and Fe(CO)2(NO)2 (177, 211). The following abbreviated correlation table indicates qualitatively how the number of predominantly metal 3d MO ionizations should increase as the molecular symmetry descends from Td to... 

The only complex in Table I with identical ligands in the two positions cis to the alkyne is the [(775-C9H7)MoL2(MeC=CMe]+ cation with L = PMe3 (72). Here the 2-butyne is parallel to one Mo—L vector and perpendicular to one Mo—L vector (Fig. 11). The 7r-ligand properties of the PMe3 ligands are probably not sufficiently dominant to create a substantial alkyne preference between the dir orbital combinations which are available. 

In this section, photophysical properties of Pd(2-thpy)2 and Pt(2-thpy)2 are compared along two lines. In a first step, properties of these two compounds are contrasted in Table 9, and in a second step, a series of properties is related to those of other organometallic compounds or metal complexes with organic ligands in Table 10. In particular, this comparison elucidates a number of clear trends and points the interesting aspects of chemical tunability. 

TeTy few investigations of the ligand properties of phosphorous acid diesters OP(H)(OR)2 have been reported, as shown in Table I. Molecules of this type are potentially interesting in that several coordination... 

Metal-nitrogen distances, as observed in a very large number of crystal structure determinations, are almost the same as those observed for the azole ligands (see Table 2) within experimental error. Comparing pyridine with substituted ligands, it is observed that substituents at position 2 (and 6) next to the donor atom have a dramatic effect upon the stoichiometry and properties of the compounds formed. It appears that a stoichiometry M(Rpy)4(anion)2 with a trans orientation of the anions is not possible, because the methyl group effectively blocks the axial coordination sites. This results in square-planar low-spin compounds for Ni and tetrahedral geometry for some other metals such as Co " and... 

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