ABSTRACT
The title compound, C(30)H(52)O(5)·2H(2)O, was degraded from pseudoginsenoside F11 which was extracted and seperated from Panax quinquefolium saponin. The three six-membered rings are in chair conformations. The five-membered ring is in an envelope conformation and the tetra-hydro-furan ring has a conformation inter-mediate between half-chair and envelope. In the crystal, inter-molecular O-Hâ¯O hydrogen bonds link mol-ecules into a three-dimensional network. Intra-molecular O-Hâ¯O hydrogen bonds also occur.
ABSTRACT
An anomalous magnetic interaction is observed in a very common and unpublished binuclear copper(ii) complex, [Cu(2)(micro(2)-OOCCH(3))(2)(bpydiol-H)(2)(H(2)O)(2)] (bpydiol-H = mono deprotonated 2,2'-bypyridine-3,3'-diol). In the complex, the two Cu(ii) ions are bridged by two acetate anions and there is a pi-pi stacking interaction between the adjacent pyridine rings. Theoretical calculations reveal that the acetate bridge ligand leads to an antiferromagnetic coupling with 2J = -166.72 cm(-1), whereas the pi-pi stacking developed a ferromagnetic interaction with 2J = 21.0 cm(-1). The offset from the antiferromagnetic interaction and the ferromagnetic interaction may be one of main factors that resulted in the weaker magnetic coupling with experimental fitting 2J = -59.61 cm(-1). This is the first example using theoretical calculations that evaluate the magnetic coupling intensity for a pi-pi stacking system.
Subject(s)
Copper/chemistry , Magnetics , Crystallography, X-Ray , Models, Molecular , Molecular Structure , Water/chemistryABSTRACT
In the title centrosymmetric binuclear complex, [Cd2(C17H11N3O)4(H2O)2](ClO4)4, the Cd(II) ion assumes a distorted octahedral geometry. There are pi-pi stacking interactions between the pyridine and 1,10-phenanthroline ring systems of adjacent ligands at the same Cd(II) centre. Intermolecular hydrogen bonds between the coordinated aqua ligand and the O atom of a keto group connect adjacent complex cations into extended chains. Hydrogen bonds also exist between the complex cations and the perchlorate anions. Compared with the fluorescence spectrum of the organic ligand, the complex displays strong fluorescent emission and an ipsochromic shift of the emission peaks, which may be attributed to the structural character.
ABSTRACT
In the title compound, {[Ag(C(30)H(20)N(6))][SbF(6)]}(n), the Ag(+) cation has a three-coordinate environment completed by three N atoms of the 1,2-bis-[(3-cyano-benzyl-idene)hydrazono]-1,2-diphenyl-ethane ligand. The Ag(+) cation coordination geometry is best described as distorted T-shaped. The crystal structure forms a three-dimensional structural polymer.
ABSTRACT
A two-dimensional coordination polymer, [Co(mu(1,3)-SCN)(2)(mu(1,6)-dmpzdo)](n)() (where dmpzdo = 2,5-dimethylpyrazine-1,4-dioxide), has been synthesized and its crystal structure determined by X-ray crystallography. In the complex, the adjacent Co(II) ions are coordinated by mu(1,3)-SCN(-) bridging ligands which forms a one-dimensional chain along the a axis; the one-dimensional chains are further connected by mu(1,6)-dmpzdo bridging ligands which leads to the formation of a two-dimensional layer on the ac plane. The theoretical calculations reveal that a ferromagnetic coupling exists between the mu(1,3)-SCN(-) bridging Co(II) ions and an anti-ferromagnetic interaction between the mu(1,6)-dmpzdo bridging Co(II) ions, and the anti-ferromagnetic interaction is stronger than the ferromagnetic interaction. The fitting of the variable-temperature (34-300 K) magnetic susceptibilities reveals that there is an anti-ferromagnetic coupling between the bridging Co(II) ions with the magnetic coupling constant J = -3.52 cm(-1).
ABSTRACT
A new one-dimensional polynuclear copper(II) complex [Cu(2)(mu(1,3)-SCN)(2)(mu'(1,3)-SCN)(2)(MPyO)(2)](n)(where MPyO = 4-methylpyridine N-oxide) has been synthesized and its crystal structure determined by X-ray crystallography. In the complex there exist two kinds of bridging coordination modes, namely, mu(1,3)-SCN(-) equatorial-equatorial (EE) bridging ligand and micro'(1,3)-SCN(-) equatorial-axial (EA) bridging ligand. Two micro(1,3)-SCN(-) EE bridging ligands coordinate two copper(II) ions in a binuclear unit, and the S atoms from the micro'(1,3)-SCN(-) EA bridging ligands as axial coordinated atoms link the binuclear units into one-dimensional chains. The ESR spectra have been investigated, and variable temperature (4-300 K) magnetic measurements were analyzed using a binuclear Cu(ii) magnetic interaction formula and indicate the existence of strong antiferromagnetic coupling with 2J=- 216.00 cm(-1) between bridged copper(II) ions. Density functional calculations have been carried out on this binuclear unit, yielding a similar singlet-triplet splitting. The mechanism of strong antiferromangetic interaction is revealed according to the calculations.
