Complexes half-sandwich tetrapyrrole

Dennis K.P. Ng, Jianzhuang Jiang, Kuninobu Kasuga and Kenichi Machida, Half-sandwich tetrapyrrole complexes of rare earths and actinides 611... 

HALF-SANDWICH TETRAPYRROLE COMPLEXES OF RARE EARTHS AND ACTINIDES... 

D.K.R Ng, J. Jiang, K. Kasuga and K. Machida conclude this volume with an overview of rare-earth and actinide half-sandwich tetrapyrrole complexes. When tetrapyrrole molecules, such as porphyrins or phthalocyanines, are reacted with the rare earths and actinides, they are split in half, forming the half-sandwich complexes because the metal atoms are larger than the core size of the macrocyclic ligands. They also can form sandwich-type complexes in which the metal centers are sandwiched between the macrocycles. However, this chapter is devoted to the former class of compounds. Ng and co-workers discuss the synthesis, structure, and spectroscopic and electrochemical properties of half-sandwich complexes of porphyrins and phthalocyanines. The authors... 

Although the redox behavior of double- and triple-decker porphyrinato complexes has been well documented, the electrochemical properties of half-sandwich analogs remain little studied. The first systematic study of the electrochemistry of this class of tetrapyrrole derivatives was reported by Kadish et al. (1991). The complex Eu(TPP)(facam) was examined, and was found to have higher stability in the oxidized and reduced forms than the corresponding acac and tmhd analogs. The compound can be prepared by treating Eu(TPP)(acac) with 3-(trifluoroacetyl)camphor (Hfacam) and sodium hydroxide in an EtOH/water mixture. As shown in fig. 12, Ae cyclic voltammograms of Eu(TPP)(facam)... 

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