Crystal structure and absolute configuration of a cobalt(III) complex of a linear tetradentate ligand: (+) 470-Δ-β-cis-dinitro(5-methyl-1,4,8,11-tetraazaundecane) cobalt(III) bromide

P. W R Corfield, J. C. Dabrowiak, E. S. Gore

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Abstract

The crystal structure and absolute configuration of a Co(III) complex of a linear tetradentate ligand, (+) 470-Δ-β-cis-dinitro(5-methyl-1,4,8,11-tetraazaundecane) cobalt(III) bromide, [Co{NH2(CH2)2NH(CH2) 2CH(CH3)NH(CH2)2NH2} (NO2)]Br, have been determined by X-ray diffraction methods. The crystals are monoclinic, with a = 13.383 (9), b = 7.724 (5), c = 7.554 (5) Å, β = 110.94 (2)°, space group P21, and Z = 2. A set of 2570 observed hkl reflections was obtained by counter methods. The molecular structure was determined by Patterson methods and refined by least squares to R1 = 0.034 with the adjustment of 270 variables. The absolute configuration was determined with the aid of 200 selected hkl reflections. The cation adopts the β-cis geometry, with the substituent methyl group adjacent to the out-of-plane chelate ring. The arrangements at the asymmetric centers are S for each nitrogen atom and R for the carbon atom. The five-membered rings both have the λ conformation, and the six-membered ring has the chair conformation, with the substituent methyl group in an equatorial position. The coordination around the cobalt atom is slightly distorted from octahedral, with angles between ( adjacent coordinated atoms varying from 85.0 (2) to 93.7 (2)°. The average Co-N(ligand) distance is 2.000 (2) Å, for three of the ligand atoms, but the in-plane terminal amino group has Co-N = 1.968 (4) Å. The Co-NO2 distances are 1.936 (2) Å.

Original languageEnglish (US)
Pages (from-to)1734-1740
Number of pages7
JournalInorganic Chemistry
Volume12
Issue number8
StatePublished - 1973

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ASJC Scopus subject areas

  • Inorganic Chemistry

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