Absorption, Circular Dichroism, and Nuclear Magnetic Resonance Studies of Bis(acetylacetonato)cobalt(III) Complexes Containing 2-Aminoalkylphosphine Chelates with Phosphorus and Nitrogen Donor Atoms

Article abstract of DOI:10.1246/bcsj.54.725

Bis(acetylacetonato)cobalt(III) complexes containing a variety of 2-aminoalkylphosphines, NH2CH2CH2P(C6H5)2, (CH3)2NCH2CH2P(C6H5)2, (S)-NH2CH(CH3)CH2P(C6H5)2, rac-NH2CH2CH2P(CH3)(C6H5), (R)-NH2CH2CH2P(C4H9)(C6H5) and NH2CH2CH2P(CH3)2, and a diphosphine, (C6H5)2PCH2CH2P(C6H5)2 were prepared and resolved (or separated) into optical isomers by SP-Sephadex column chromatography.Absorption, circular dichroism, and 1H and 13C NMR spectra of the new complexes were measured and the results compared with those of the related complexes.Positions of the 2-aminoalkylphosphine and the related ligands in the spectrochemical series were as follows; CN^- > NH2CH2CH2P(CH3)2 > (C6H5)2PCH2CH2P(C6H5)2 > NH2CH2CH2P(CH3)(C6H5) <*> NH2CH2CH2P(C4H9)(C6H5) > NH2CH(CH3)CH2P(C6H5)2 <*> NH2CH2CH2P(C6H5)2 <*> NH2CH2CH2NH2 > (CH3)2NCH2CH2P(C6H5)2.For the 13C NMR spectra, all the signals including those due to two diastereotopic phenyl groups on a phosphorus atom were assigned, and the chemical shifts and the coupling constants were determined.The methyl and carbonyl carbons which are trans to a phosphorus atom give a doublet signal due to four-bond (⁴J(C,P) = 6-7 Hz) and three-bond ³J(C,P) = 2-3 Hz) couplings, respectively, through a cobalt(III) ion.