Crystal and molecular structures of the acetylacetonate derivatives 2 and 2

Article abstract of DOI:10.1016/0022-328X(89)85248-9

All attempts to synthesise Se^IV derivatives of acetylacetone resulted in the formation of Se^II complexes with the selenium atom coordinated to the methine carbon atom of the ligand.The crystal structure of 2 (where acac=CH3C(O)CC(O)CH3) shows a Se-Se separation of 2.9007(4) Angstroem. 2 contains two independent molecules within the unit cell and steric restraints are less severe, so that the Se-Se separation is approximately 3.34 Angstroem.Crystals of 2 are monoclinic, space group P2₁/c with Z=2, a 6.9979(9), b 7.881(2), c 10.843(2) Angstroem and β 94.26(1) deg.Crystals of 2 are triclinic, space group P1, with Z=4, a 9.796(2), b 10.675(1), c 17.162(2) Angstroem, α 73.504(9), β 88.71(1), γ 74.00(1) deg.For both complexes there is evidence for stereochemically active lone electron pairs on the Se atoms.