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Configuration of Octahedral Metal Compounds − Equilibrium, Crystal and Molecular Structure of Nickel( II ) Complexes of Linear N 2 O 4 , N 4 S 2 or N 6 Donors Set Atoms Ligands
Author(s) -
Mohamadou Aminou,
Jubert Caroline,
Gruber Nathalie,
Barbier JeanPierre
Publication year - 2004
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.200300648
Subject(s) - chemistry , nickel , hexacoordinate , perchlorate , crystallography , ligand (biochemistry) , octahedron , thioether , bond length , spectrochemical series , metal , crystal structure , cobalt , ligand field theory , inorganic chemistry , stereochemistry , ion , organic chemistry , biochemistry , receptor , silicon
Two new nickel( II ) complexes of symmetric hexadentate mixed‐ligand N,O [1,12‐bis(2‐pyridyl)‐5,8‐dioxa‐2,11‐diazadodecane (pydado)] and N,S [1,12‐bis(2‐pyridyl)‐5,8‐dithia‐2,11‐diazadodecane (pydadt)] donor atoms have been synthesised as perchlorate salts and characterised by X‐ray crystallography and ligand‐field spectroscopy. In both complexes the Ni 2+ ion is hexacoordinate. The cation [Ni(pydado)] 2+ is pseudo‐octahedral with the two pyridyl groups in trans position; all Ni−N and Ni−O bond lengths are practically equivalent. In [Ni(pydadt)] 2+ complex, however, the size of the thioether sulfur atoms imposes a C 2 v symmetry; the pyridyl groups and the sulfur atoms are in trans positions and all Ni−N bond lengths are equivalent. The comparison of these structures with those of octahedral cobalt, copper and zinc complexes with the same ligands shows that their configurations depend not only on the nature of the two central donor atoms of the ligand, but also on the nature of the metallic ion. In aqueous solution, the stability constants of the Ni II chelates with these two ligands, determined by potentiometry, show the formation of [Ni(LH)] 3+ and [NiL] 2+ species in all cases. The chelating power of the pydadt ligand is slightly greater than that of pydado. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)