Molecular structure of bis(L-leucinato)zinc(II) and single-crystal EPR spectra of the substitutionally copper(II)-63-doped complex (original) (raw)

1989, Inorganic Chemistry

The title compound, Zn[H2NCHC02CH2CH(CH3)2]2 (abbreviated as Zn(~-Leu)~), crystallizes in the monoclinic system, space group PZI, with a = 9.584 (4) A, b = 5.389 (2) A, c = 14.866 (3) A, 6 = 106.84 (3)O, and Z = 2. The structure was solved by X-ray diffraction techniques employing 1355 independent reflections and refined by the least-squares method to an agreement factor R = 0.048. The two L-leucine molecules per formula unit act as bidentate ligands of the Zn(I1) ion, forming a N202 squashed tetrahedral configuration. The carboxyl oxygen of a third amino acid molecule completes a pentagonal coordination around Zn(I1). The crystal structure of Z n (~-L e u )~ was compared to the quasi-isomorphous structure of the C u (~-L e u )~ complex. Room-temperature EPR data of substitutional 63Cu(II) impurities in single crystals of Zn(~-Leu), were taken at 34 GHz. From these data we obtained g' = 2.273 (I), g' = 2.055 ( l ) , g' = 2.066 ( l ) , AIcu = 167.3 (2) X lo4 cm-I, A*,, = 0 (8) X lo4 cm-I, and A3Cu