2 CHROMIUM(II) COMPLEXES WITH AMIDATO-LIKE LIGANDS - A COMPOUND WITH THE LONGEST CR-CR BOND AND A MONONUCLEAR COMPOUND WITH D2D SYMMETRY

Reactions of chromium(II) with ligands that possess an amidato portion have been investigated, and products of two reactions been structurally characterized by X-ray crystallography. They show very different chemical behavior. The 2.550(4) angstrom chromium-chromium distance in the dinuclear saccharinate, Cr2(C7H4NO3S)4-2THF (I), is the longest found so far in any chromium(II) dimer. Compound I also has the shortest chromium-axial ligand distance, Cr-L(ax). The reaction of Cr2OAc4.2H2O with lithium diethylbarbiturate yielded the mononuclear complex Li2Cr(C8H11N2O8)4-2C2H5OH (2), in which the ligand binds to the metal center in a monodentate fashion and there are only Cr-N bonds, which might be taken as an extreme manifestation of a Jahn-Teller Effect. The anion is further distorted from planarity and the coordination about the chromium atom has S4 symmetry. The crystallographic data for 1 are: space group C2/c, u = 22.467(5), b = 21.458(5), c = 11.640(7) angstrom, beta-112.85(2)-degrees, V = 5171(3) angstrom 3, Z = 4; and those for 2 are; space group Fdd2, a = 27.036(9), b = 17.154(4), c = 20.777(9) angstrom, V = 9636(10) angstrom 3, Z = 8.