SYNTHESIS AND CHARACTERIZATION OF COBALT(III) COMPLEXES CONTAINING ALPHA-DIAMINE AND CARBINOLAMINE DERIVED FROM ALPHA-AMINOMALONATE AND ETHYLENEDIAMINE

The α-aminomalonate anion (AM2−) undergoes a C-N bond formation reaction with trans-[CoCl2{en)2)+(en = ethylenediamine) in the presence of triethylamine (Et3N) to produce α-diamine and carbinolamine complexes. The reaction in water under air gives the carbinolamine complex 3 predominantly whereas the reaction under N2yields the α-diamine complex 2 preferentially. These complexes were characterized by absorption and 1H and 13C NMR spectroscopy and elemental analysis. The X-ray crystal structure of the α-diamine complex 2b ([Co(N-(2-aminoethyl)-α,α-diaminomalonato)(en)]Cl·0.5H2O) has been determined: formula C7H17N5O4CoCl0·5H2O, space group Pl (triclinic); a = 13.196 (4) Å, b = 13.212 (5) Å, c = 7.259 (3) Å, α = 93.78 (3)°, β = 89.00 (3)°, γ = 92.80 (3)°, Z = 4, R = 0.056. The free OH group of the carbinolamine complex 3 ([Co(N-(2-amino-ethyl)-α-amino-α-hydroxymalonato)(en)]C1O4·H2O) was confirmed by 1H NMR in DMSO-d6with the addition of D2O. Of great interest is that the C-N bond formation reaction occurs on the sp3carbon of the AM2−ion. © 1990, American Chemical Society. All rights reserved.