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Complexes of Tetradentate Ligands Containing Phosphorus and Arsenic
Author(s) -
Venanzi L. M.
Publication year - 1964
Publication title -
angewandte chemie international edition in english
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 0570-0833
DOI - 10.1002/anie.196404531
Subject(s) - chemistry , denticity , crystallography , ligand (biochemistry) , trigonal bipyramidal molecular geometry , octahedron , arsenic , metal , ligand field theory , chromium , spectrochemical series , paramagnetism , diamagnetism , stereochemistry , inorganic chemistry , crystal structure , ion , organic chemistry , magnetic field , biochemistry , physics , receptor , quantum mechanics
The effect of ligand shape on coordination numbers and geometry of coordination compounds has been studied using two tetradentate ligands containing phosphorus and arsenic. These tend to form five‐coordinate complexes with trigonal bipyramidal structure [Fe(II), Co(I), Co(II), Rh(I), Ni(II), Pd(II), Pt(II)], but can also form six‐coordinate complexes with octahedral structure [Fe(II), Ru(II), Os(II), Co(III), Rh(III), Pd(IV), Pt(IV)]. The magnetic properties and the stereochemistry of the complexes are explained by ligand field theory which predicts that, for metal ions with d 6 ‐electronic configuration, a low overall field strength should favor the formation of five‐coordinate paramagnetic complexes while a high overall field strength should favor the formation of six‐coordinate diamagnetic complexes. – This work provides further indication that the tendency of polydentate ligands to use all the potential donor atoms is not as pronounced as is generally believed. This is shown by the isolation of chromium(III) complexes in which the tetradentate ligands are, in fact, acting as tridentate, and by the isolation of mercury(II) complexes where only two of the four donor atoms of the polydentate ligand are actually bonded to the central metal atom.