Solution conformations of CaCl sub 2 and Ca(NO sub 3 ) sub 2 complexes of chiral tetramethyl 18-crown-6 macrocycles: A 1D and 2D sup 1 H and sup 13 C NMR investigation

Journal Article · Wed Oct 04 00:00:00 EDT 1989 · Inorganic Chemistry; (USA)

DOI:https://doi.org/10.1021/ic00319a030· OSTI ID:7245946

Lewison, J F; Ghirardelli, R G; Palmer, R A ^[1]

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1. Duke Univ., Durham, NC (USA)

One- and two-dimensional NMR techniques have been used to investigate the solution structures of (2S,6S,11S,15S)-2,6,11,15-tetramethyl-1,4,7,10,13,16-hexaoxacyclooctadecane (I) and (2R,3R,11R,12R)-2,3,11,12-tetramethyl-1,4,7,10,13,16-hexaoxyacyclooctadecane (II) macrocycle complexes of CaCl{sub 2} and Ca(NO{sub 3}){sub 2} in CDCl{sub 3}. Previous chiroptical studies of these and similar crown complexes by circularly polarized luminescence (CPL), total luminescence (TL), and circular dichroism (CD) spectroscopy have shown that the macrocycle asymmetric carbons in these complexes constrain the ring such that the sense of the ring twist in the S chiral ring complexes is opposite to that in the R chiral ring complexes. These studies have also shown that there is an added chirality element in the di- and trivalent (alkaline earth and lanthanide metal, respectively) nitrate complexes of I and II associated with the twist of the nitrate anions relative to one another as they sterically interact with the ring methyl groups. It has been proposed that channels are created on each face of the macrocycle ring by the axially positioned methyl groups in the solution structures of the I and II complexes and that the planar nitrate anions are constrained to fit in these channels. In this study, we show that the NMR data do indeed support the prominent axial positioning of the methyl groups in the CaCl{sub 2} and Ca(NO{sub 3}){sub 2} complexes of I and II in solution. Furthermore, the NMR data are consistent with the assertion that the S chiral ring (I) twists in an opposite sense to the R chiral ring in these complexes. The data for this conformational analysis were obtained by exploiting coupling constant information and the nuclear Overhauser effect, observed by using both one- and two-dimensional NMR techniques. 34 refs., 8 figs., 2 tabs.

• OSTI ID: 7245946
• Journal Information: Inorganic Chemistry; (USA), Journal Name: Inorganic Chemistry; (USA) Vol. 28:20; ISSN 0020-1669; ISSN INOCA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
400202 -- Isotope Effects
Isotope Exchange
& Isotope Separation
ALCOHOLS
ALKALINE EARTH METAL COMPOUNDS
BARYONS
CALCIUM CHLORIDES
CALCIUM COMPOUNDS
CALCIUM HALIDES
CALCIUM NITRATES
CARBON 13
CARBON ISOTOPES
CHIRAL SYMMETRY
CHLORIDES
CHLORINATED ALIPHATIC HYDROCARBONS
CHLORINE COMPOUNDS
CHLOROFORM
DATA
DEUTERIUM COMPOUNDS
ELEMENTARY PARTICLES
EVEN-ODD NUCLEI
EXPERIMENTAL DATA
FERMIONS
GLYCOLS
HADRONS
HALIDES
HALOGEN COMPOUNDS
HALOGENATED ALIPHATIC HYDROCARBONS
HYDROGEN COMPOUNDS
HYDROXY COMPOUNDS
INFORMATION
ISOTOPES
LIGHT NUCLEI
NITRATES
NITROGEN COMPOUNDS
NMR SPECTRA
NUCLEI
NUCLEONS
NUMERICAL DATA
ORGANIC CHLORINE COMPOUNDS
ORGANIC COMPOUNDS
ORGANIC HALOGEN COMPOUNDS
ORGANIC POLYMERS
OXYGEN COMPOUNDS
POLYETHYLENE GLYCOLS
POLYMERS
PROTONS
SPECTRA
STABLE ISOTOPES
SYMMETRY