ISSN:
1572-901X
Source:
Springer Online Journal Archives 1860-2000
Topics:
Chemistry and Pharmacology
Notes:
Summary The structures of NiII complexes of the macrocyclic ligands 1,4,7,10,13-pentaazacyclopentadecane, [15]aneN5 and 1,5,9,13,17-pentaazacycloeicosane, [20]aneN5 have been determined. [Ni(C10H25N5)H2O]-(NO3)(ClO4) monoclinic, space group P21/n,a=8.265(3)Å,b=6.201(6)Å,c=13.672(4)Å, β=93.35(3)°· 2394 unique reflections were used in the structure determination and the refinement proceeded to an R value of 0.045. The ligand is coordinated to the metalvia all five nitrogens in theracemic conformation and a water molecule completes the coordination sphere of the metal ion. The complex cation shows considerable distortion from octahedral geometry which may rationalise the unusual spectroscopic properties and the low enthalpy of formation of the complex cation. [Ni(C15H35N5)](NO3)2·H2O monoclinic, space group P21/n,a=15.437(9)Å,b=9.573(6)Å,c=15.942(8)Å, β=109.24(4)°. 2715 unique observed reflections were used in the structure refinement which proceeded to an R value of 0.035. The five nitrogens of the macrocycle are bound to Ni(II) in a distorted square pyramidal coordination geometry. The NiII lies 0.35Å above the basal plane of the four nitrogen atoms.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF01024079
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