Issue 11, 1983

Synthesis, characterization, and crystal structure analysis of pentane-2,4-dionato(1,4,7,10-tetra-azacyclododecane)cobalt(III) diperchlorate monohydrate and its brominated complex (3-bromopentane-2,4-dionato)(1,4,7,10-tetra-azacyclododecane)cobalt(III) diperchlorate hemihydrate

Abstract

Pentane-2,4-dionato(1,4,7,10-tetra-azacyclododecane)cobalt(III) diperchlorate (1) reacts with N-bromosuccinimide to give its brominated complex, (3-bromopentane-2,4-dionato)(1,4,7,10-tetra-azacyclododecane)cobalt(III) diperchlorate (2). The complexes have been characterized by elemental analyses, electrical conductivity measurements, i.r., 1H n.m.r., and electronic spectra. The three-dimentional X-ray crystallographic structure determination of the title complexes confirmed the completion of bromination at the 3-position of the pentane-2,4-dionato-moiety without altering the stereochemistry of the co-ordination sphere and macrocyclic ligand. The parent (1) crystallizes in the space group Pna21, with a= 18.974(6), b= 13.403(4), c= 8.928(2)Å, and Z= 4, while complex (2) crystallizes in the space group Pbca, with a= 15.138(4), b= 21.360(5), c= 14.066(7)Å, and Z= 8. The structures were solved by the heavy-atom method to give R= 0.0499 and 0.0635 for (1) and (2), respectively. The cobalt ion is co-ordinated in a distorted octahedral fashion with the four nitrogen atoms of the 12-membered macrocyclic ligand and two oxygen atoms of the pentane-2,4-dionato-moiety in a cis position, in which the distortion from the regular octahedron is found in the donor nitrogen atoms of the macrocyclic ligand. The six-membered chelate ring consisting of the 3-bromopentane-2,4-dionato group and the cobalt ion slightly deviates from the overall planarity, with deviations of 0.19 and 0.18 Å for the Co and Br atoms, while the planarity of the corresponding chelate ring of (1) is preserved within ±0.04 Å. The cation of (1) exhibits a mirror plane passing through the pentane-2,4-dionato-moiety, Co, and two nitrogen atoms in a cis position, while for the brominated complex (2) the symmetry is not preserved due to the deviation from overall planarity of the chelate ring.

Article information

Article type
Paper

J. Chem. Soc., Dalton Trans., 1983, 2405-2410

Synthesis, characterization, and crystal structure analysis of pentane-2,4-dionato(1,4,7,10-tetra-azacyclododecane)cobalt(III) diperchlorate monohydrate and its brominated complex (3-bromopentane-2,4-dionato)(1,4,7,10-tetra-azacyclododecane)cobalt(III) diperchlorate hemihydrate

N. Matsumoto, A. Hirano, T. Hara and A. Ohyoshi, J. Chem. Soc., Dalton Trans., 1983, 2405 DOI: 10.1039/DT9830002405

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