Preparation, Resolution, and Absorption and Circular Dichroism Spectra of [Co(en)<i>n</i>{NH2CH2CH2P(CH3)2}3−<i>n</i>]3+ and the Related Complexes, and the Absolute Configuration of (+)589-<i>fac</i>-[Co{NH2CH2CH2P(CH3)2}3]3+ Determined by X-Ray Analysis

Abstract

Abstract A series of complexes, [Co(en)n{NH2CH2CH2P(CH3)2}3−n]3+ (en=ethylenediamine, n=0,1,2) and three bis(ethylenediamine)cobalt(III) complexes of the related ligands, NH2CH2CH2P(C6H5)2, (S)-NH2CH(CH3)CH2P(C6H5)2, and rac-NH2CH2CH2P(C4H9)(C6H5) were prepared and resolved (or separated) into optical isomers, and their absorption and circular dichroism spectra were recorded. The molecular structure and the absolute configuration of (+)589-fac-[Co{NH2CH2CH2P(CH3)2}3]Br3·3H2O were determined by X-ray analysis. The crystals are lemon-yellow, orthorhombic, a=26.501(8), b=9.573(4), c=10.081(5) Å, space group P212121, z=4. The Co atom is surrounded by 3P and 3N in the facial manner with the average distances of 2.237 and 2.041 Å, respectively. The absolute configuration of the complex ion is Δ. The chelate rings are puckered and chiral to form a pseudo λ gauche conformation.