TM EDA,

The influence of different additives on the apparent pKa values of diphenylmethane, 4-methyl-pyridine and the deprotonation rate of triphenylmethane was investigated 3 TM EDA caused the highest enhancement. 

The successful us6 of the furan dianion (46) for the. synthesis of 2,5-disubstitutad furariB depends on the presence of TM.EDA during metallation. In the absen-ce of TMEDA, nucleophilic attack at the oxime may be observed., The course of the lithiation of furan-... 

Xie and co-workers reported the N-arylation of imidazole in refluxing methanol in the presence of catalytic cuprous chloride or cupric acetate in air [26]. Yields are higher than the catalytic [Cu(OH) TM EDA 2C]l2 condition first introduced by Collman and co-workers [33a, b]. Similarly, the same conditions are applicable to phfhalamides [26], also with better yields than previously reported by Lam and co-workers [33c], Conversely, for aniline and sulfonamide substrates, Xie s conditions gave lower yield than Lam s conditions [33c]. Likewise, for basic amines, Batey s conditions [27] are superior. 

Scheme 8.21 Ethylidenation of thioester and amide with Zn-CH3CH Br2-TiCl4-TM EDA.

AIBN = 2,2 -azobisisobutyronitrile 9-BBN = 9-borabicyclo [3.3.1]nonane Bn = benzyl BOC = f-butoxycarbonyl Bz = benzoyl CAN = ceric anunoninm nitrate Cp = cyclopenta-dienyl Cy = cyclohexyl DAST = diethylaminosnllur trifln-oride DBA = l,3-dibromo-5,5-dttnethylhydantoin DDQ = 2,3-dichloro-5,6-dicyano-l,4-benzoquinone DET = diethyl tartrate DIAD = diisopropyl acetylene dicarboxylate DIBAL-H = diisobutylalummum hydride DIPEA = diisopropyl ethyl amine DMDO = dimethyldioxirane HMPA = hexamethylphosphortriamide EDA = lithium diisopropy-lamide Ms = methylsulfonyl MOM = methoxymethyl NBS = iV-bromosuccmimide NMO = A-methylmorpholine iV-oxide PDC = pyridinium dichromate PMP = p-methoxyphenyl THP = tetrahydropyranyl TIPS = trisiso-propylsilyl TMANO = trimethylamine A-oxide TBDMS = t-butyldimethylsilyl Tf = trifluoromethanesulfonyl TMP = 2,2,6,6-tetramethylpiperidyl TMS = trimethylsilyl Ts = p-toluenesulfonyl. 

In this chapter we summarize our systematic investigations of the namre of the chemical bond in transition metal (TM) molecules [17-37] and main group compounds [37-43] employing an energy decomposition analysis (EDA) which was originally developed by Morokuma [44] for ab initio methods and by Ziegler and Rank [45] for DFT methods. The EDA method has been further developed by Baerends and coworkers... 

The EDA results of the group-10 homoleptic complexes TM(EMe)4 (E = B-Tl, TM = Ni, Pd, Pt) are given in Table 13.23. The data indicate that the statement concerning significant Fe ER Tr-backdonation holds also true for other transition metals. In TM(EMe)4 (TM = Ni, Pd, Pt), the contribution of TM —> EMe ir-backdonation is between 33-49% of the covalent term However, the bonding... 

To compare previously discussed low-valent transition metal compounds with high-valent transition metal compounds, the former results can be compared with the energy decomposition analyses of the complexes Cl4TM-C2H t (TM = Cr, Mo, W). The EDA results are given in Table 13.32. 

The EDA results of the parent compounds show, that all three components of AEjn, vary parallel with the total interaction energy. Due to the larger TM- -H2 distance in Mo(CO)sH2, both the repulsive Pauli interaction and the attractive electrostatic and orbital interactions are considerably weaker in this complex. The larger decrease in the attractive interactions as compared to that in the Pauli forces leads to ca. 3 kcal/mol destabilization with respect to Cr(CO)5H2 and W(CO)5H2. On the other hand, the ratio of the electrostatic and orbital interactions, and that of the components of is rather... 

A related case where the hybridization of the interacting orbitals plays a crucial role for the strength of the energy terms of the EDA has been found for the phosphane complexes (COijTM-PMej and (COijTM-PClj (TM = Cr, Mo, W), which are discussed in Vol. 2, Chapter 7. 

A comparative analysis of phosphane complexes (COljTM-PRj (TM = Cr, Mo, W), which possess different substituents R, with NHC complexes (COljTM-NHC with the help of EDA calculations provides deep insights into the nature of the metal-ligand interactions. Since the metal fragment W(CO)5 has also been used in the earlier chapter about carbonyl complexes, it is possible to compare the... 

The EDA results for the metal-ligand interactions in the metallacyclic compounds CI4TM-C2H, (TM = Mo, W), which are shown in Table 7.7, are very different from the data for the ethylene and acetylene complexes. There are no results for the chromium compounds because of SCF problems [34]. The electron-sharing... 

In order to recognize the overall symmetry of the orbitals, which are shown in Figure 7.14, one must consider one horizontal and one vertical mirror plane of the complex. Thus, the aj and a2 orbitals of the complexes have o-symmetry, the ej and ejg orbitals have Jt-symmetry, and the e2g and e2 orbitals have 8-symmetry. According to the qualitative bonding model shown in Figure 7.14, the a- and Ji-orbitals describe TM L donation, whereas the 8-orbitals describe TM L backdonation. The strength of the different orbital interactions and the contributions that come from electrostatic attraction and PauH repulsion may be quantitatively estimated with EDA calculations. The numerical results are shown in Table 7.10. 

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