名称:
Chiral Discrimination of Complexes with D3 Symmetry. Synthesis and Characterization of Tris{O,O'-bis[(+)(S)-2-methylbutyl] dithiophosphato}chromium(III) Complexes (.LAMBDA..DELTA.){Cr[(+)(S)(S)Mebdtp]3} and .LAMBDA.-(-)589-, and .DELTA.-(+)589{Cr[(+)(S)(S)Mebdtp]3} and Crystal Packing of Racemic Tris{O,O'-diethyl dithiophosphato}chromium(III), Cr[ddtp]3
摘要:
Synthesis of the title chiral complex (Lambda Delta){Cr[(+)(S)(S)Mebdtp](3)}, with (+)(S)(S)Mebdtp(-) = (+)[(S)-(CH3CH2-CHCH3CH2O)(2)PS2](-), O,O'-bis[(+)(S)-2-methylbutyl] dithiophosphate ion, as the ligand, was accomplished in solution with various solvents giving rise in all cases to a higher production of Lambda-(-)589 {Cr[(+)(S)(S)Mebdtp](3)} diastereoisomer than Delta-(+)(589){Cr[(+)(S)(S)Mebdtp](3)}. The formation reaction was followed by absorption and CD spectroscopy. The Lambda-(S,S)(S,S)(S,S) diastereoisomer proved to have higher stability in all the solvents employed (ethanol, acetone, acetonitrile, benzene, dichloromethane, chloroform, and water). Crystal packing forces seem to favor an equal mixture assembly of Lambda- and Delta-{Cr[(+)(S)(S)Mebdtp](3)}, as is evident from CD characterization of the solid precipitated from solutions with a slight excess of the Lambda(-)-isomer. Configurational inversion was observed in solution and even in the solid state after a long time if the solid was kept at higher temperature and under vacuum, although the chirality favored was different in the two phases. The molecular structure and crystal-packing mode of the related title complex {Cr[ddtp](3)}, ddtp(-) = (C2H5O)(2)PS2-, (C12H30CrO6P3S6, formula weight 607.64) were determined from single-crystal X-ray diffraction data and refined by full-matrix least squares methods to R = 0.065. Crystals are monoclinic, with a = 14.512(8) Angstrom, b = 13.657(3) Angstrom, c = 14.350(2) Angstrom, beta = 90.42(3)degrees, V = 2844(2) Angstrom(3), Z = 4, and space group C2/c (No. 15). The crystals contained a racemic mixture of Lambda- and Delta-Cr[ddtp](3) enantiomers. The discussion based on the structural information of this compound extends to chiral discrimination in the formation reaction, configurational inversion reaction, molecular structure, and crystal packing of (Lambda Delta){Cr[(+)-(S)(S)Mebdtp](3)}.