Structures macrocyclic complexes

Square planar Ni11 macrocyclic complexes are typically yellow, red, or brown in color and absorb around 400 500 nm, depending on the ligand structure. The octahedral Ni11 complexes absorb at 500A100 nm. 

Using 1,4,8,11-tetraazacyclotetradecane, the structure of complex (800) (distorted trigonal planar Cu-Cu 6.739 A) was determined. Reactivity with 02 was investigated to demonstrate the formation of trans-l,2-peroxo species.585 As part of their work with copper(I) complexes with 02, the structure of a dicopper(I) complex ((801) distorted tetrahedral 7.04 A), supported by macrocyclic ligand environment, was reported by Comba and co-workers. Tolman and co-workers structurally characterized a three-coordinate copper(I)-phenoxide complex (802) (planar T-shaped) that models the reduced form of GO.587 The copper(I) analogue [Cu(L)][CF3-SO3]-0.43MeOI I (803) of a copper(II) complex (534) was also reported to demonstrate the role of ligand framework conformability in CV /Cu1 redox potentials.434 Wilson and co-workers... 

A very large number of synthetic, as well as many natural, macrocycles have now been studied in considerable depth. A major thrust of many of these studies has been to investigate the unusual properties frequently associated with cyclic ligand complexes. In particular, the investigation of spectral, electrochemical, structural, kinetic, and thermodynamic aspects of macrocyclic complex formation have all received considerable attention. 

Xue M, Chen CF (2008) Triptycene-based tetralactam macrocycles synthesis, structure and complexation with squaraine. Chem Commun 46 6128-6130... 

The structure of the Ni(II) macrocycle complex has been reported in Figure 108, whereas that of the Ni(III) monocation is shown in Figure 110.160... 

An example of electrochemically induced trans— cis isomerization is given by the macrocyclic complex rra j-[MnnI(cyclam)Cl2]+, the molecular structure of which is illustrated in Figure 9.9... 

The molecular structure of a Co(II) macrocycle complex that in some way mimics the strapped-type metal-porphyrin complexes is illustrated in Figure 13.18 19... 

Figure 49 shows the molecular structure of the macrocyclic complex trans-[ Mo°(N 2)2Me8[ 16]aneS4], 68... 

Anion effects have been observed especially in relation to dissolution of the cation complexes in media of low polarity. Soft organic and inorganic anions (phenates, thiocyanate, permanganate etc) generally allow ready dissolution the pier ate anion has been much used (62, 66). The interaction between the anion and the complexed cation may affect the stability of the complex. Ion pairing may occur when the anion can contact the complexed cation, as in the case of macrocyclic complexes, where approach of the anion from top and bottom is possible. This is observed in the RbNCS complex of IS, but not in its NaNCS complex, as shown by the crystal structure data (100). With bromide as anion both a complexed ion pair and a complexed sodium cation are found in the solid state for (15, NaBr) (118). 

H. Takemura, H. Kariyazono, M. Yasutake, N. Kon, K. Tani, K. Sako, T. Shinmyozu, T. Inazu, Syntheses of macrocyclic compounds possessing fluorine atoms in their cavities Structures and complexation with cations, Eur. J. Org. Chem. 1 (2000) 141-148. 

This review deals with syntheses, properties, structures, and reactions of Ni(II), Ni(III), and Ni(I) macrocyclic complexes that have been reported over the past few years. 

The Ni—N bond distances, N-N bite distances, and N-M-N bite angles of Ni(II) macrocyclic complexes depend on the coordination number of the metal ion and the type of macrocycle. These structural parameters influence the electronic spectra and the electrochemical data. In general, Ni—N bond distances of square-planar complexes are shorter than those of the octahedral complexes because of the absence of electrons in dx2 . Furthermore, as the Ni—N bond distance in-... 

The structural parameters of various Ni(II) macrocyclic complexes are summarized in Table III. Square-planar Ni(II) complexes with saturated macrocyclic ligands have Ni—N bond distances ranging from 1.90 to 1.95 A, depending on the type of ligand. The Ni—N bond distances increase when square-planar Ni(II) complexes bind axial ligands to form octahedral species. For example, the square-planar Ni(II) complex... 

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