Synthesis and structures of two cobalt complexes [NaCo^II(NTA)(H₂O)]_n and NH₄[Co^III(IDA)₂] · 2H₂O

Abstract

Two cobalt complexes [NaCo^II(nta)(H₂O)] _n (H₃nta = nitrilotriacetic acid) (1) and NH₄[Co^III(ida)₂] · 2H₂O (H₂ida = iminodiacetic acid) (2) have been synthesized and characterized by single-crystal X-ray diffraction analysis. Compound 1 crystallizes in the orthorhombic system, space group P2₁2₁2₁ with a = 7.9770(12) Å, b = 9.7613(15) Å, c = 12.1945(18) Å, V = 949.5(2) ų, Z = 4, and R ₁ = 0.0705 for 1597 observed reflections. Compound 2 crystallizes in the monoclinic system, space group P2(1)/c with a = 5.1801(3) Å, b = 11.2073(6) Å, c = 12.2891(7) Å, V = 707.09(7) ų, Z = 2, and R ₁ = 0.0349 for 1143 observed reflections. In compound 1, the Co is coordinated by a nitrogen and five oxygen atoms in a distorted octahedral geometry {CoNO₅}, and the Na is coordinated by one water molecule and four carboxyl oxygen atoms in slightly distorted square pyramidal geometry. The entire structure shows a three-dimensional network. In compound 2, Co atom is equatorially coordinated by two ida ligands in a distorted octahedral geometry {CoN₂O₄}. The discrete [Co(ida)₂]²⁻ anions are linked by hydrogen bonding to a three-dimensional supramolecular network.

Keywords:

• Cobalt
• Nitrilotriacetic acid
• Iminodiacetic acid
• Crystal structure

Acknowledgements

This work was supported by the 973 program of the MOST (001CB108906), the National Natural Science Foundation of China (20425313, 90206040, 20333070, 20303021), the NSF of Fujian Province and the State Key Laboratory of Structural Chemistry (030065).