CHELATING MODES OF 3-SUBSTITUTED 2,4-PENTANEDIONES - CRYSTAL AND ELECTRONIC-STRUCTURE OF BIS(3-CYANO-2,4-PENTANEDIONATO)COBALT(II)

Coordination modes of 3-substituted 2,4-pentanediones are considered with respect to the chemical nature of the substituent and the conformational flexibility of the ligand. Examples of additional and competitive coordination of the extra donor site(s) are given, and two different pathways for the structural rearrangement in such complexes are discussed. Accordingly, a new constitution of the acetylacetone cyanation intermediate product 4 in its Cu and Ni complexes is speculated. The 3D network structure of the title compound in which all functional groups are involved in coordination is determined (C12H12CoN2O4, tetragonal, space group P42)/n, a = 14.444 (1) angstrom, c = 6.832 (2) angstrom, D(x) = 1.431 g cm-3, Z = 4, R = 0.0217), and its solid-state electronic spectrum is analyzed in terms of the angular overlap model.