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Bulletin of the Korean Chemical Society (BKCS)

ISSN 0253-2964(Print)
ISSN 1229-5949(Online)
Volume 18, Number 9
BKCSDE 18(9)
September 20, 1997 

1H NMR Study of Aziridine Derivatives Coordinated to the Paramagnetic Undecatungstocobalto(Ⅱ)silicate and -nickelo(Ⅱ)silicate Anions
Suk Min Park, Hyunsoo So*
1H NMR spectra of D2O solutions containing 2,2-dimethylaziridine (1) or 2-methylaziridine (2) and [SiW11COⅡO39]6- (SiW11Co) or [SiW11NiⅡ O39]6- (SiW11Ni) exhibit separate signals for the free ligand and the complex, indicating that the ligand exchange is slow on the NMR time scale. Identified are two linkage isomers with the methyl group of 2 at trans or cis position with respect to the metal. The isotropic shifts of 1 and 2 coordinated to SiW11Ni originate mainly from the contact shifts, and they agree reasonably with the relative values reported for similar ligands coordinated to bis(2,4-pentanedionato)nickel(Ⅱ). The isotropic shifts for the SiW11Co complexes were separated into contact and pseudocontact contributions. The pseudocontact shifts show that (χ∥-χ⊥) is positive, while that for the SiW11Co complexes of pyridine derivatives is negative. This result indicates that the ordering of dxy and dxz, dyz orbitals in SiW11Co complexes can be reversed by ligands.
1002 - 1006
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