Transition metals coordinated open-chain

Open chain polyamine ligands have been widely studied. Often the coordination of zinc is compared with other first row transition metals and factors, such as behavior across a pH range, studied. The protonation patterns and stability constants are of particular interest. Octahedral zinc tris(ethylenediamine) structures have been characterized by X-ray diffraction with a number of different counter anions.94 The X-ray structure of zinc tris(ethylenediamine) with fluoride counter ions reveals extensive hydrogen bonding.95... 

The reactions of dihydrobilin (1,19-dideoxybiladiene-a, c) with transition metals are strongly influenced by the nature of the metal ion. Thus with Mn(OAc)3 or FeClj the corresponding metallocorrolates have been obtained in high yield, in the presence of chromium or ruthenium salts the reaction product isolated has been the metal free macrocycle, while coordination of rhodium requires the presence of an axial ligand such as a phosphine, arsine or amine [21]. Neutral pentacoordinated rhodium complexes have thus been obtained. Although analysis of the electronic spectra of the reaction mixtures demonstrated that cyclization of the open-chain precursor and formation of metallocorrolates occur even in the absence of extra ligands, no axially unsubstituted rhodium derivative has been reported. 

The existence of terminal P—O groups in AlPO-CSC and AIPO-ESC suggests that these 1-D chains might have a potential to further condense to give rise to more complex frameworks.[196] Experimentally, 3-D open frameworks have been successfully built up through the coordination of transition metal ions to the terminal oxygen atoms of 1-D AlPO-CSC. The AlPO-CSC structure is kept intact in the 3-D open frameworks/197,1981... 

Fig. 3 The macrocycle A incorporating a coordinating fragment thick line) interacts with a metal center black circle) and an asymmetrical open chain chelate B bearing one porphyrin and a precursor function X which is small enough to pass through the ring after the threaded intermediate C is formed, the additional porphyrin ring is constructed, affording the transition metal-complexed rotaxanes D and E. Demetalation leads to the free-ligand rotaxanes F and G from D and E, respectively...

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