Group trends complexes

The series M(PP)C1 (PP = 2,ll-bis(diphenylphosphinomethyl)benzo[c]-phenanthrene M = Cu, Ag, Au) is interesting in showing group trends (Table 4.7) where the silver and copper complexes have trigonal coordination and the gold member is linear [50]. 

In keeping with the usual group trend, selenium and even more so tellurium show cationic behavior, which manifests itself in the formation of complexes and organo derivatives. We can deal here only with a few leading examples. 

Ru(II) and Os(II) Complexes. The trends observed for the complexes of the metals of the groups 9 and 10, that is, higher negative charge density on... 

The energy of the M — C bond of homoleptic transition metal compounds increases as the atomic number of the element in the group becomes greater. In the case of main group complexes, this trend is opposite. The stability of the M—C bond also increases... 

In the heteronuclear Ru(III)-Fe(II)-Ru(II) system listed in Table 1.1, Ru-Fe transitions but not Ru-Ru are seen in the spectrum. Electrochemical studies of a series of mixed-metal/mixed-valence complexes have been used to estimate mixed-valence stabilization effects. For example, in a series M [Fe(CN)5] , where M may be an organic group or a metallo-organic group, trends in Fe(III/II) can be correlated with electrostatic interactions, but they also reveal small mixed-valence stabilization effects. 

A major trend in organic synthesis, however, is the move towards complex systems. It may happen that one needs to combine a steroid and a sugar molecule, a porphyrin and a carotenoid, a penicillin and a peptide. Also the specialists in a field have developed reactions and concepts that may, with or without modifications, be applied in other fields. If one needs to protect an amino group in a steroid, it is advisable not only to search the steroid literature but also to look into publications on peptide synthesis. In the synthesis of corrin chromophores with chiral centres, special knowledge of steroid, porphyrin, and alkaloid chemistry has been very helpful (R.B. Woodward, 1967 A. Eschenmoser, 1970). 

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