Macrocyclic ligands nomenclature

Macrocyclic ligands, mainly tetraaza macrocycles, have been widely used in stabilizing nickel(III). No nickel(IV) species has been isolated, although many nickel(III) complexes with dianionic macrocyclic ligands undergo one-electron oxidation. In this section we will use the nomenclature of Section 50.5.9 to indicate the macrocycles. 

For a discussion of the nomenclature of the macrocyclic ligands, and for the derivation of the abbreviations used to represent these ligands, see p. 2... 

In order to comply with current lUPAC nomenclatiue rules for metallated tetrapyrroles (as e.g. in hemes or Vitanun B12 derivatives), the configuration having the fifth metal ligand below the tetrapyrroHc macrocycle, which is numbered in a clockwise fashion is denoted as a, while the configuration has the fifth Hgand above the macrocycle. This nomenclature compUes also with the one proposed by Sharpless for the direction of attack of an asym-... 

Dockal etal. [57] used slow-scan CV to determine the 21 values for 17 Cu(II/I) complexes in 80% methanol —20% water (w/w) - including nine complexes with macrocyclic terdentate, quadridentate, quinquedentate, and sexaden-tate thioethers and eight complexes with acyclic quadridentate ligands containing thioether sulfur and/or amine nitrogen donor atoms. (In naming the denticity of multidentate ligands, Dwyer, Lions, and coworkers have pointed out that dentate is a Latin root and proper nomenclature requires that Latin prefixes be used. 

Several methods have been used to distinguish between diastereoisomers in more complex systems. Thus, stereoisomers resulting from the coordination of linear tetradentate ligands have often been identified as trans, cis-a, or c/s-( S,10 and those resulting from coordination of macrocyclic tetradentate ligands have their own system.11 The scope of most of these nomenclatures is generally quite limited, but a proposal with wider application in the description of complexes of polydentate ligands has been made more recently.12... 

For example, dibenzo[18]crown-6 is a crown ether with an 18-membered macrocyclic ring containing six oxygen atoms with two benzo substituents. A more generalised system of nomenclature for such neutral organic ligands was developed by Vogtle and Weber, and later modified by in which... 

Fig. 4 BCM a with chiral atoms indicated by asterisks. At right the lUPAC numbering is given. Note that in the a configuration the ligand to the metal is on the opposite side of the macrocycle to the 17 propionic acid residue, while in the p configuration they are on the same side. As a mnemonic rule, the j8-configuration can be derived by a left-hand rule where the thumb points to the ligand when the fingers are pointing in a clockwise (or nomenclature-wise) fashion...

The literature available from the end of the last report (December 1989) to September 1991 is covered in this chapter. A complete revision of the International Union of Pure and Applied Chemistry (lUPAC) " Nomenclature for Inorganic Chemistry has appeared and lUPAC-recommended ligand abbreviations will be used wherever possible. Research activity in chromium chemistry continues at about the same level as in the past, but there are odd surges as new techniques " or complexes become available. As in previous years, the general chemistry of chromium has been reviewed. l Other, more specialist reviews include the spectroscopy of Cr(VI), organochromium(III) chemistry,and macrocyclic complexes of chromium in various oxidation states.Closer to the mechanistic area is a review of the photophysics of chromium(III) complexes and, more specifically, the photochemical water-exchange process in chromium(III) complexes. A summary of new insights into the mechanism of spontaneous and base-catalyzed substitution reactions of inert-metal amine complexes has also appeared. ... 

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