Alkaloids as Ligands. 1. Synthesis and Characterization of Three Cobalt(II) Pseudohalide Compounds Containing L-sparteine
The alkaloid l-sparteine (sp) combines with cobalt(II) cyanate, thiocyanate, and selenocyanate to form pseudotetrahedral, N-bonded four-coordinate complexes of the type Co(sp)(NCX)2 (X = O, S, or Se). Their electronic spectra indicate that Co(Sp)(NCSe)2 is nearly tetrahedral whereas Co(sp)(NCO)2 and Co(Sp)(NCS)2·1/2H2O are more severely distorted from tetrahedral geometry. This distortion is observed in the low-symmetry splitting of the ν2 and ν3 ligand field transitions which is ca. twice as large in the isocyanate and isothiocyanate complexes as in the isoselenocyanate complex which exhibits a splitting of ca. 2000 cm-1 for ν2 and 1000 cm-1 for ν3. Apparently the isoselenocyanate complex maintains a nearly regular tetrahedral geometry by changing the conformation of the A ring of l-sparteine from the chair to the boat conformation. Pseudohalide stretching and bending modes are identified and found to be similar to those of other complexes containing nitrogen-coordinated pseudohalides. For the isocyanate, isothiocyanate, and isoselenocyanate compounds cobalt-tertiary nitrogen stretching frequencies are 465, 498, and 473 cm-1, respectively. Below 400 cm-1 two cobalt-pseudohalide nitrogen stretching bands for each compound are identified.
J. T. Wrobleski and G. J. Long, "Alkaloids as Ligands. 1. Synthesis and Characterization of Three Cobalt(II) Pseudohalide Compounds Containing L-sparteine," Inorganic Chemistry, vol. 16, no. 3, pp. 704-709, American Chemical Society (ACS), Mar 1977.
The definitive version is available at https://doi.org/10.1021/ic50169a041
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© 1977 American Chemical Society (ACS), All rights reserved.