Isostructural cobalt(II) and zinc(II) complexes of the N,N-bis(carboxymethyl)-β-alaninato(3−) ion. Crystal structure of the cobalt(II) derivative, [Co(H2O)6][Co2L2(H2O)2]·4H2O

Homonuclear compounds [M(H 2 O) 6 [M 2 L 2 (H 2 O) 2 ]·4H 2 O (M(II)Co(II) or Zn(II), L 3− =anion of N , N -bis(carboxymethyl)-β-alanine or ((2-carboxyethyl)imino)diacetic acid) have been synthesized and characterized by chemical analysis, magnetic susceptibility data and/or IR spectra, thermal analysis and X-ray diffraction method. They are isostructural and crystallize in the triclinic system, space group P 1 with Z =1. The crystal structure was determined for the cobalt(II) compound ( a =8.732(7)- b =9.751(6), c =9.918(5) A, α=99.96(4), β=110.88(5), γ=103.79(5), V =734.6A 3 , D meas =1.80 g cm −3 , D exp =1.80 g cm −3 ,μ=1.767 mm − (MoKα)). Final R =0.034 and R w =0.043 for 3145 independent observed reflections. This compound consists of both centrosymmetric hexaaquocobalt(II) cations (Co(1)-OW(1)=2.046(2), (Co(1)-OW(2)=2.077(2), Co(1)-OW(3)=2.119(2) A) and anions [Co 2 L 2 (H 2 O ) 2 ] 2− , and non-coordinated water molecules. In the homodinuclear chelate anions, each cobalt(II) atom is bonded to one water molecule (Co( 2 )-OW(4)=2.098(2) A) and one tetradentate chelating ligand L 3− (Co(2)−N=2.134(2), Co(2)−O(5)=2.113(2), Co(2)−O(13)=2.081 (2), Co(2)-O(23)=2.101(2) A). The dimer has an imposed C i symmetry. One carboxylate oxygen atom from the β-alanine arm acts as a bridge between the two cobalt atoms so completing the octahedral coordination of cobalt. The values of the distances Co(2)−Co(2 i ) and the angle at the oxygen atom Co(2)−O(5)−Co(2 i ) are 3.2934(7) A and 103.5(1) o respectively.