ISSN:
1573-1111
Keywords:
X-ray crystal structure
;
tetramethylcyclam
;
ring conformation
;
molecular modelling
Source:
Springer Online Journal Archives 1860-2000
Topics:
Chemistry and Pharmacology
Notes:
Abstract The X-ray crystal structure of 1,4,8,11-tetramethyl-1,4,8,11-tetraazacyclotetradecane has been determined. The neutral ligand crystallises in the triclinic space groupP $$\bar 1$$ with unit cell parametersa=8.467(4),b=10.057(5),c=10.637(5) Å, α=67.68(3), β=75.38(4), γ=76.34(4)°,V=800.75 Å3 andD c=1.063 g cm−3 forZ=2.R=0.047 for 2140 unique observed (I/σ(I)≥2.0) reflections (R w=0.052). Two crystallographically independent molecules are observed. Both are centrosymmetric and adopt a mesodentate conformation. Molecule (1) is identified as the (R, S, S, R)-[trans-IV] isomer and molecule (2) as the (R, R, S, S)-[trans-III] isomer. Molecular mechanics calculations provide a basis for understanding the structural and energetic relationships between the neutral and protonated forms of this tetraazamacrocyclic ligand.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00709074
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