Structural Relationships obtained from the Coordination of α-Picolinamide to the (Iminodiacetato)copper(II) Chelate: Synthesis, Crystal Structure, and Properties of (α-Picolinamide)(iminodiacetato)copper(II) Dihydrate

Abstract

The stoichiometric reaction of copper(II) hydroxycarbonate, iminodiacetic acid (H2IDA = HN(CH2CO2H)2) and α‐picolinamide (pya) in water yields crystalline samples of (α‐picolinamide)(iminodiacetato)copper(II) dihydrate, [Cu(IDA)(pya)] · 2 H2O (1). The compound was characterised by thermal (TG analysis with FT‐IR study of the evolved gasses), spectral (IR, electronic and ESR spectra), magnetic and single crystal X‐ray diffraction methods. It crystallises in the triclinic system, space group P1, a = 8.8737(4), b = 10.23203(5), c = 15.7167(11) Å, α = 77.61(1)°, β = 103.89(1)°, γ = 80.32(1)°, Z = 4, final R1 = 0.056. The asymmetric unit contains two crystallographic independent molecules but chemically very similar ones. The CuII atom exhibits a square base pyramidal coordination (type 4 + 1). pya acts as N,O‐bidentate ligand supplying two among the four closest donor atoms of the metal [averaged bond distances (Å): Cu–N = 1.982(2), Cu–O(amide) = 1.972(2)]. IDA plays a N,O,O′‐terdentate chelating role [averaged bond distances (Å): Cu–N = 2.004(3), Cu–O = 1.941(2) and Cu–O = 2.242(2)]. The coordinating behaviour of pya in 1 is discussed on the basis of its N,O‐bidentate chelating role and the preference of the ‘Cu‐iminodiacetato' moiety [Cu(IDA)] to link the N‐heterocyclic donor of pya in trans versus the Cu–N(IDA) bond. Consistently the ligand pya is able to impose a fac‐chelating configuration to IDA one around the copper(II) as previously has been reported to mixed‐ligand complexes having a 1/1/2 CuII/IDA/N(heterocyclic) donor ratio or a closely related 1/1/1/1 CuII/IDA/N(heterocyclic)/N(aliphatic) one.

Antimicrobial and SOD activities of novel transition metal complexes of pyridine-2,6-dicarboxylic acid containing 4-picoline as auxiliary ligand

“…The extent of tetragonality (T) is estimated [36] as the ratio of the mean in-plane bond distances to the mean of the longer distances. The magnitude of T (T ¼ 0.93) for the present complex is within the range (T ¼ 0.91-0.96) reported [37] for an axially distorted octahedral structure in the presence of Jahn-Teller distortion.…”

Calixarene‐Based Picolinamide Extractants for Selective An/Ln Separation from Radioactive Waste

“…Among these ligands, N-alkylpicolinamides have also been proposed as ligands for the selective extraction of An from radioactive waste [2,20,21] as they show promising separation factors (S Am/Eu Ϸ 9) under optimum conditions. They can act as bidentate ligands, as evidenced in the solid-state structure of a Cu II salt [22] or by molecular modelling [23] on lanthanide complexes, where both the pyridine N and the carbonyl oxygen atoms are coordinated to the metal ion. Alternatively, examples of picolinamides acting as monodentate ligands (through the pyridine nitrogen) [24] or, under basic conditions, as bidentate ligands through the deprotonated amide NH rather than the carbonyl group [25] are also known.…”

Tricarbonyltechnetium(I) and tricarbonylrhenium(I) complexed with N-methyl-2-pyridinecarboxyamide as potential radiopharmaceuticals: a computational study

“…The anionic ligand 2,6-pyridine bis-amide, with N,N 0 -donor atoms, is able to stabilize first row metal ions in high (equal or greater than ?3) oxidation states due to its strong sigma-donor capability [11]. The N,O-coordination mode, in turn, has been demonstrated crystallographically for the complexes with V(IV) [12], Fe(II), Co(II), [13], Ni(II) [13,14], Ni(III) [15], Cu(II) [15,16], Co(II) [17], and Zn(II) [17]. On the other hand, for the Co(II) picolinamide complex, a monodentate structure has also been postulated based on the spectrophotometric/ potentiometric studies (N 0 -complex in Scheme 2) [18].…”