Complexes of 2, 6‐Bis(hydroxymethyl)pyridine with Different Copper(II) Salts Involving the Anions Chloride, Perchlorate, Nitrate and Acetate. Synthesis and Crystal Structures of the Complexes

Abstract

Complexes of 2, 6‐bis(hydroxymethyl)pyridine (dhmp) with different CuII salts [CuCl2·6H2O, Cu(ClO4)2·6H2O, Cu(NO3)2·3H2O, Cu(CH3COO)2·H2O] are prepared (1—5, respectively), studied by IR, and their crystal structures reported. Dependent on the anion kind, influences on the distortion of the co‐ordination polyhedron, the distribution of donor sites, the formation of a mono‐ or binuclear complex, and the resultant packing structure of the complex are observed, although in no case the counterions of the used CuII salts or water of hydration were found in the co‐ordination sphere. Crystal structures of 1—5 indicate hexaco‐ordination of the CuII ions with N2O4‐environment and show that 1—4 are mononuclear 2:1 (L:M) complexes, but 5 is a binuclear 4:2 complex. Crystallization of Cu(ClO4)2·6H2O with dhmp yielded two different complexes (2/3). In 3, one of the dhmp components is mono‐deprotonated and acts as an anionic ligand. The same behavior is found in 5. Whereas in the neutral ligand complexes 1, 2 and 4 the basal planes are occupied by O donors, and N atoms are in the axial positions of the octahedrons, in 3 and 5 the bases are formed by two O and two N donor atoms, and O atoms are in the axes. Moreover, complex 3 shows the N atoms in trans position, but 5 in cis position. The packing of the cationic complex units is typical of strong and weak H bond interactions involving the counterions and hydroxylic or aromatic hydrogen atoms to yield complex network structures.

Oxido Pincer Ligands – Exploring the Coordination Chemistry of Bis(hydroxymethyl)pyridine Ligands for the Late Transition Metals

“…Four further copper complexes [(pydimH 2 ) 2 Cu] 2+ have been crystallised with structural parameters very similar to our structure with the pydipH 2 ligand. The axial N–Cu bonds are also rather short in this complex, with values ranging from 1.935(4) Å to 2.102(3) Å, clearly indicating a Jahn–Teller‐like compression 14b. A number of nickel complexes [(pydimH 2 ) 2 Ni] 2+ with various counterions (Cl – , NO 3 – , SO 4 2– , p ‐TolOSO 3 – ) have also been reported.…”

“…Interestingly, a complex[(pydimH 2 )(pydimH)Co III ]Cl 2 was obtained, in which deprotonation of the ligand occurs concomitantly with oxidation of the central metal atom (Co II to Co III ). Similarly, a Cu II complex containing a partially deprotonated ligand – [(pydimH 2 )(pydimH)Cu]ClO 4 – was reported 14b. In both cases the corresponding M–O bonds are about 10 % shorter than the corresponding bonds with protonated O atoms (M–OH).…”

“…In contrast to this, late transition metals usually coordinate to RR′pydimH 2 in its protonated form, as in [M(pydimH 2 ) 2 ] 2+ (M = Co, Ni, Cu, Zn)13–15 [Cu(O 2 CCH 2 CH 3 ) 2 (pydimH 2 )],16 [Cu(nif) 2 (pydimH 2 )] {nif = niflumate,2‐{[3‐(trifluoromethyl)phenyl]amino}nicotinate},17 or [Cu(pydic)(pydimH 2 )] 18. Exceptions to this rule have been found for the Cu II complexes [Cu 2 (η 2 ,μ‐pydimH) 2 (η 3 ‐pydimH 2 ) 2 ] 2+[14b,19] and [Cu(pydimH 2 )(pydimH)] + 14b…”

Cytotoxic and Antimicrobial Properties of Copper(II) Complexes of Pyridine and Benzimidazole Derivatives

“…Syntheses of Complexes 1–3, 5, 6: Syntheses of the copper(II) complexes 1 – 3 , 5 , and 6 were performed according to previously described procedures in the literature, , and, , respectively. The ligands: 4‐pmOpe, 2‐bimOpe, and 2‐bis(pm)Ope were synthesized as described previously , , …”

“…The presented study aims to evaluate in vitro cytotoxic activity against B16 melanoma and 10T1/2 fibroblasts cell lines as well as antimicrobial activity of the copper(II) complexes of phosphate or hydroxymethyl derivatives of pyridine and benzimidazole, as shown in Scheme …”