Nitromalonaldehyde as a Ligand. Synthesis and Reactivity with Isocyanides of Monomeric Tris(ligand)metal(II) Complexes and Crystal Structure of Pentakis(4-methylphenyl isocyanide)cobalt(I) Tris(nitromalonaldehydo)cobaltate(II)

The syntheses and characterization of the first monomeric tris(β-dicarbonyl) species of cobalt(II) and iron(II) have been achieved by using nitromalonaldehyde (NMA) as the ligand. The reaction between NMA and several other metal(II) chlorides (M = Zn, Ni, Cu, Pt, Pd) is also presented, and the results are tentatively explained on the basis of both steric and electronic properties of the dialdehyde ligand compared with various substituted acetylacetonates. Furthermore, the reactivity of some nitromalonaldehyde complexes with isocyanides has been investigated, and a new method to synthesize the [Fe(CNR)6]2+ and [Cu(CNR)4]+ cations is described. In the case of (nitromalonaldehyde)cobalt(II) complexes, reaction with isocyanides gives [Co(CNR)5][Co(NMA)3] (R = 4-CH3C6H4, 4-CH3OC6H4, 4-N02C6H4, 4-ClC6H4). The crystal structure of [Co(4-CH3C6H4NC)5][Co(NMA)3] is built up of discrete monomeric octahedral [Co(NMA)3]- anions and trigonal-bipyramidal [Co(CNR)5]+ cations. The crystals are triclinic, of space group PI, with unit cell dimensions a = 14.29 (1) Å, b = 16.60 (1)Å, c = 12.19 (1)Å,α = 109.2 (1)°, β = 110.0 (1)°, γ = 94.1 (l)1 23456, and Z = 2. A total of 1942 observed reflections have been measured by single-crystal diffractometry and refined by full-matrix least squares to R = 0.109. © 1981, American Chemical Society. All rights reserved.