Markiewicz, Maria; Wiewiorowski, Maciej, Bulletin de l'Academie Polonaise des Sciences, Serie des Sciences Chimiques, 1981, vol. 29, # 9-10, p. 407 - 422
Probing the metal complexing ability of bis-quinolizidine N-oxides: Synthesis, spectroscopy and crystal structures
摘要:
New ZnX2 (X = Cl, Br) complexes with sparteine N1-oxide, sparteine epi-N16-oxide, lupanine (2-oxosparteine) N-oxide and alpha-isosparteine N-oxide were obtained and characterized by spectroscopic and crystallographic methods. Complexation with N1-oxides involves inversion of the configuration at the N16 atom of sparteine, converting its C ring from a boat into a chair form, whereas the structure of sparteine epi-N16-oxide, typified by the trans boat/chair C/D quinolizidine moiety, remains unchanged upon complexation. Coordination of zinc salts in the above compounds is realized solely through the oxygen atom of the N-O group and is accompanied by protonation of the "not-N-oxide" nitrogen atom. At variance lupanine N-oxide forms bis-monodentate complexes with ZnX2 utilizing both the N-oxide and the lactam carbonyl oxygen atoms to bridge the neighboring ZnX2 units, while reaction of alpha-isosparteine N-oxide with ZnX2 leads to formation of complex salts of the general formula [H(-)alpha-Sp(N-oxide)][(ZnX3)(H2O)]. (C) 2011 Elsevier Ltd. All rights reserved.