CHIRAL DISCRIMINATION OF COMPLEXES WITH D-3 SYMMETRY - SYNTHESIS AND CHARACTERIZATION OF TRIS(O,O'-BIS[(-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)()(S))

Synthesis of the title chiral complex (Lambda Delta){Cr[(+)(S)(S)Mebdt p](3)}, with (+)(S)(S)Mebdtp(-) = (+)[(S)-(CH3CH2-CHCH3CH2O)(2)PS2](-) , O,O'-bis[(+)(S)-2-methylbutyl] dithiophosphate ion, as the ligand, w as accomplished in solution with various solvents giving rise in all c ases to a higher production of Lambda-(-)589 {Cr[(+)(S)(S)Mebdtp](3)} diastereoisomer than Delta-(+)(589){Cr[(+)(S)(S)Mebdtp](3)}. The forma tion reaction was followed by absorption and CD spectroscopy. The Lamb da-(S,S)(S,S)(S,S) diastereoisomer proved to have higher stability in all the solvents employed (ethanol, acetone, acetonitrile, benzene, di chloromethane, chloroform, and water). Crystal packing forces seem to favor an equal mixture assembly of Lambda- and Delta-{Cr[(+)(S)(S)Mebd tp](3)}, as is evident from CD characterization of the solid precipita ted from solutions with a slight excess of the Lambda(-)-isomer. Confi gurational inversion was observed in solution and even in the solid st ate 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 relate d title complex {Cr[ddtp](3)}, ddtp(-) = (C2H5O)(2)PS2-, (C12H30CrO6P3 S6, formula weight 607.64) were determined from single-crystal X-ray d iffraction 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 = 2 844(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) enantiom ers. The discussion based on the structural information of this compou nd extends to chiral discrimination in the formation reaction, configu rational inversion reaction, molecular structure, and crystal packing of (Lambda Delta){Cr[(+)-(S)(S)Mebdtp](3)}.