Structural Variety of Isopropyl-bis(2-picolyl)amine Complexes with Zinc(II) and Copper(II)

Abstract

A variety of structurally different complexes of the isopropyl-bis­(2-picolyl)­amine ( i Pr-bpa) ligand were prepared with ZnA2 and CuA2 salts (A = Br–, Br–/PF6 –, BF4 –/F–, ClO4 –). The choice of different counterion affected the stoichiometry, coordination number, geometry, and formation of geometrical isomers. Crystal structures of four Zn­(II) complexes, namely, two monomers ( mer -[Zn­( i Pr-bpa)­Br 2 ] and fac -[Zn­( i Pr-bpa)­Br 2 ]), one F–-bridged dimer ([Zn 2 (μ-F) 2 ( i Pr-bpa) 2 ]­(BF 4 ) 2 ), and one ML 2 complex ([Zn­( i Pr-bpa) 2 ]­(ClO 4 ) 2 ) were determined, and their solution structures were studied by NMR spectroscopy. For the ML 2 complex, relative stabilities of geometrical isomers were determined using density functional theory calculations. For Cu­(II) complexes, five crystal structures were determined, namely, two monomers ([Cu­( i Pr-bpa)­Br 2 ] and [Cu­( i Pr-bpa)­(ClO 4 ) 2 (H 2 O)]), a Br–-bridged dimer ([Cu 2 (μ-Br)­(Br) 2 ­( i Pr-bpa) 2 ]­(PF 6 )), a F–-bridged coordination polymer ([Cu­(μ-F)­( i Pr-bpa)] n (BF 4 ) n × nCH 3 OH), and a cyclic, CO3 2–-bridged trimer ([Cu 3 (tri-μ-CO 3 )­(ClO 4 ) 3 ­( i Pr-bpa) 3 ]­(ClO 4 )). The different crystallographic structures of Cu­(II) complexes are reflected in their different magnetic properties investigated by electron spin resonance spectroscopy and magnetic susceptibility measurements.

Tuning the coordination properties of chiral pseudopeptide bis(2-picolyl)amine and iminodiacetamide ligands in Zn(ii) and Cu(ii) complexes

“…After MD simulations identified representative structures of free ligands and different isomers of ML and ML 2 complexes with Zn( ii ) in solution, these were used as starting points for the DFT geometry optimization employing a very efficient M05-2X/6-31+G(d)/LanL2DZ+ECP model, known to be successful in reproducing geometries, dipole moments, and homolytic bond energies in various metal complexes, 73,74 and in line with our comparative analysis with other DFT approaches on similar systems. 29 To account for the effect of the acetonitrile solution, during geometry optimization, we included the implicit SMD solvation model ( ε = 35.688), as employed in our earlier studies. 31 Thermal corrections were extracted from the corresponding frequency calculations, so that all of the presented results correspond to differences in the Gibbs free energies at room temperature.…”

“…Herein, we studied metal complexes of bis(2-picolyl)amine (bpa) and iminodiacetamide (imda) ligands with a side chain containing a remote chiral center. In the ML 2 complexes, three isomers can form: mer , trans – fac and cis – fac , and the bpa and imda chelating groups were chosen as ligands with a preference for formation of cis – fac 28–30 and trans – fac 31,32 isomers, respectively. Other than the type of ligand, the formation of different isomers depends on additional factors, such as the type of metal center, counterion, and non-covalent interactions.…”

Self‐Assembly of Cobalt(II) Coordination Polymers with Differently Halosubstituted Nicotinate Ligands and 4,4’‐Bipyridine – The Effect of the Halosubstituent Positions on Polymer Types

“…Also, during geometry optimization we included the implicit SMD solvation with all parameters for pure water, in line with our earlier reports that used the same approach to interpret solid-state features of a variety of metal complexes. [49][50][51][52] Atomic charges were obtained through the natural bond orbital (NBO) analysis [53] by the same model. All calculations were performed using the Gaussian 16 software.…”

Multi-Oxyanion Detection by an Organic Field-Effect Transistor with Pattern Recognition Techniques and Its Application to Quantitative Phosphate Sensing in Human Blood Serum

“…In comparison to relatively complicated binuclear complex-based receptors composed of zinc­(II)-dpa, − Cu II -dpa-based mononuclear complexes are capable of capturing Pi even in the simpler chemical structures . Two or three vacant coordination sites in the Cu II -dpa complex can be the recognition scaffold for the detection of Pi . Toward on-site sensing of oxyanions including Pi, the realization of a solid-state sensing platform is a valid strategy.…”